ordering code about color

ordering code about color

@private type my_custom_shaderProgram = {
  program: Webgl.WebGLProgram;
  vertexPositionAttribute: Webgl.GLint;
  vertexNormalAttribute: Webgl.GLint;
  pMatrixUniform: Webgl.WebGLUniformLocation;
  mvMatrixUniform: Webgl.WebGLUniformLocation;
  nMatrixUniform: Webgl.WebGLUniformLocation;
  ambientColorUniform: Webgl.WebGLUniformLocation;
  lightingDirectionUniform: Webgl.WebGLUniformLocation;
  useLightingUniform: Webgl.WebGLUniformLocation
};

@private type static_buffer = {
  positions: Webgl.WebGLBuffer;
  itemSize: int; numItems: int;
  normals: Webgl.WebGLBuffer
};

@private type engine.scene = list(object);

@private type engine = {
  context: Webgl.Context.private;
  canvas: { selector:dom; width: int; height: int };
  shaderProgram: my_custom_shaderProgram
  static_buffers: { repcoords: { x:static_buffer; y:static_buffer; z:static_buffer } };
  framePickBuffer: Webgl.WebGLFramebuffer;
  scene: engine.scene
  selector: dom
} ;

@client initPickBuffer(eng) =
  gl = eng.context;
  framePickBuffer = Webgl.createFramebuffer(gl);
  renderPickBuffer = Webgl.createRenderbuffer(gl);
  pickTexture = Webgl.createTexture(gl);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.some(pickTexture));
  tex = Webgl.Uint8Array.from_int_list([0, 0, 0]);
  do Webgl.texImage2D(gl, Webgl.TEXTURE_2D(gl), 0, Webgl.RGB(gl), eng.canvas.width, eng.canvas.height, 0, Webgl.RGB(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(tex));
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(framePickBuffer));
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.some(renderPickBuffer));
  do Webgl.renderbufferStorage(gl, Webgl.RENDERBUFFER(gl), Webgl.DEPTH_COMPONENT16(gl), eng.canvas.width, eng.canvas.height);
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.none);

  do Webgl.framebufferTexture2D(gl, Webgl.FRAMEBUFFER(gl), Webgl.COLOR_ATTACHMENT0(gl), Webgl.TEXTURE_2D(gl), pickTexture, 0);
  do Webgl.framebufferRenderbuffer(gl, Webgl.FRAMEBUFFER(gl), Webgl.DEPTH_ATTACHMENT(gl), Webgl.RENDERBUFFER(gl), renderPickBuffer);
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.none);
  framePickBuffer
;

initShaders(gl) =
  f(e, str) =
    shader = Webgl.createShader(gl, e);
    do Webgl.shaderSource(gl, shader, str);
    do Webgl.compileShader(gl, shader);
    shader;
  fragmentShader = f(Webgl.FRAGMENT_SHADER(gl), CustomShaders.shader_fs);
  vertexShader = f(Webgl.VERTEX_SHADER(gl), CustomShaders.shader_vs);
  // TODO getShaderParameter
  shaderProgram = Webgl.createProgram(gl);
  do Webgl.attachShader(gl, shaderProgram, vertexShader);
  do Webgl.attachShader(gl, shaderProgram, fragmentShader);
  do Webgl.linkProgram(gl, shaderProgram);
  // TODO : getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
  do Webgl.useProgram(gl, shaderProgram);
  shaderProgram =
    vertexPositionAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexPosition");
    vertexNormalAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexNormal");
    do Webgl.enableVertexAttribArray(gl, vertexPositionAttribute);
    do Webgl.enableVertexAttribArray(gl, vertexNormalAttribute);
    { program = shaderProgram;
      ~vertexPositionAttribute;
      ~vertexNormalAttribute;
      pMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uPMatrix");
      mvMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uMVMatrix");
      nMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uNMatrix");
      ambientColorUniform = Webgl.getUniformLocation(gl, shaderProgram, "uAmbientColor");
      lightingDirectionUniform = Webgl.getUniformLocation(gl, shaderProgram, "uLightingDirection");
      useLightingUniform = Webgl.getUniformLocation(gl, shaderProgram, "uUseLighting");
    };
  shaderProgram
;

initLineXBuffers(gl, orient) =
  (vertices, vertexNormals) = match orient with
    | {x} -> ([ 0.0, 0.0, 0.0, 5.0, 0.0, 0.0 ], [ 2.5, 0.0, 0.0,        2.5, -1.0, 0.0 ])
    | {y} -> ([ 0.0, 0.0, 0.0, 0.0, 5.0, 0.0 ], [ 0.0, 2.5, 0.0,        -1.0, 2.5, 0.0 ])
    | {z} -> ([ 0.0, 0.0, 0.0, 0.0, 0.0, 5.0 ], [ 0.0, 0.0, 2.5,        0.0, -1.0, 2.5 ])
    end ;
  vertexPositionBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexPositionBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertices)),
    Webgl.STATIC_DRAW(gl));
  vertexNormalBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexNormalBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertexNormals)),
    Webgl.STATIC_DRAW(gl));
  { positions=vertexPositionBuffer; itemSize=3; numItems=2; normals=vertexNormalBuffer }
;

setMatrixUniforms(gl, shaderProgram, pMatrix, mvMatrix) =
  a =
    b = mat4.to_list(pMatrix);
    c = Webgl.Float32Array.from_float_list(b);
    c;
  e =
    f = mat4.to_list(mvMatrix);
    g = Webgl.Float32Array.from_float_list(f);
    g;
  do Webgl.uniformMatrix4fv(gl, shaderProgram.pMatrixUniform, false, a);
  do Webgl.uniformMatrix4fv(gl, shaderProgram.mvMatrixUniform, false, e);
  normalMatrix = mat3.create();
  do mat4.toInverseMat3(mvMatrix, normalMatrix);
  do mat3.transpose(normalMatrix, normalMatrix);
  do Webgl.uniformMatrix3fv(gl, shaderProgram.nMatrixUniform, false, Webgl.Float32Array.from_float_list(mat3.to_list(normalMatrix)));
  void
;

setup_boxes(eng) =
  cnf_x(pos) = { pos with f1=0.0 }; cnf_y(pos) = { pos with f2=0.0 }; cnf_z(pos) = { pos with f3=0.0 };
  g(x:int, y:int, w:int, h:int, clear_near_far) =
    inbox(pos) = (pos.x_px >= x) && (pos.y_px >= y) && (pos.x_px < (w + x)) && (pos.y_px < (h + y));
    { ~x; ~y; ~w; ~h; ~inbox; ~clear_near_far } ;
  compute_left_right(x) = if ((mod(x, 2)) == 0) then
      a = (x / 2);
      ((a, a), 0)
    else
      b = (x / 2);
      ((b, b+1), 0);
  ((w_l, w_r), e_w) = compute_left_right(eng.canvas.width);
  ((h_u, h_d), e_h) = compute_left_right(eng.canvas.height);
  { _YX=g(0, h_d+e_h, w_l, h_u, cnf_z); _YZ=g(w_l+e_w, h_d+e_h, w_r, h_u, cnf_x);
    _ZX=g(0, 0, w_l, h_d, cnf_y);       _3D=g(w_l+e_w, 0, w_r, h_d, cnf_y) }
;

which_box(b, pos) =
  if b._YX.inbox(pos) then {_YX}
  else if b._YZ.inbox(pos) then {_YZ}
  else if b._ZX.inbox(pos) then {_ZX}
  else if b._3D.inbox(pos) then {_3D}
  else {out}
;

fetch_box(b, who) = match who with
  | {_YX} -> b._YX
  | {_YZ} -> b._YZ
  | {_ZX} -> b._ZX
  | {_3D} -> b._3D
  end ;

drawScene_for_a_viewport(eng, who, viewport, eye, up, scene, mode) =
  gl = eng.context; shaderProgram = eng.shaderProgram; repcoords = eng.static_buffers.repcoords;
  do Webgl.viewport(gl, viewport.x, viewport.y, viewport.w, viewport.h);
  pMatrix =
    tmp_pMatrix = mat4.create();
    tmp_x = Float.of_int(viewport.w / 40)
    tmp_y = Float.of_int(viewport.h / 40)
    match who with
    | {_YX} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      tmp_pMatrix
    | {_YZ} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      mat4.rotateY(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_ZX} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      mat4.rotateX(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_3D} ->
      do mat4.perspective(45., float_of_int(eng.canvas.width) / float_of_int(eng.canvas.height), 0.1, 100.0, tmp_pMatrix);
      c = mat4.create() ;
      do mat4.lookAt(vec3.from_public(eye), vec3.from_public((0.0, 0.0, 0.0)), vec3.from_public(up), c);
      do mat4.multiply(tmp_pMatrix, c, tmp_pMatrix);
      tmp_pMatrix
    end ;
  mvMatrix =
    tmp_mvMatrix = mat4.create();
    do mat4.identity(tmp_mvMatrix);
    Stack.push(Stack.create(), tmp_mvMatrix);
  do setMatrixUniforms(gl, shaderProgram, pMatrix, Stack.peek(mvMatrix));
  draw_rep(r, g, b, rep) =
    do Webgl.uniform3f(gl, shaderProgram.ambientColorUniform, r, g, b);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.positions);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexPositionAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.normals);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexNormalAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.drawArrays(gl, Webgl.LINES(gl), 0, rep.numItems);
    void ;

  _ =
    match mode with
    | {normal} ->
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false
      do draw_rep(1.0, 0.0, 0.0, repcoords.x);
      do draw_rep(0.0, 1.0, 0.0, repcoords.y);
      do draw_rep(0.0, 0.0, 1.0, repcoords.z);
      do match who with
        | {_3D} ->
          do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 1); // 1 = true
          Webgl.uniform3f(gl, shaderProgram.lightingDirectionUniform, 0.85, 0.8, 0.75)
        | _ -> void end;
      List.iter((object -> display(eng, pMatrix, mvMatrix, object, false)), scene)
    | {pick} ->
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(eng.framePickBuffer));
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false;
      do List.iter((object -> display(eng, pMatrix, mvMatrix, object, true)), scene);
      void
    end ;

  (pMatrix, mvMatrix)
;

@private drawScene_and_register(org_eng, get_scene : (->Scene.Client.scene), get_mode) =
  viewbox = setup_boxes(org_eng) ;
  rec aux(eng:engine) =
    gl = eng.context;
    (eng, scene) =
      f(is_selected, p) =
        match List.find((z_in_mem -> z_in_mem.id == p.id), eng.scene) with
        | { some=in_mem } -> { in_mem with position=p.cube; ~is_selected; color=p.color }
        | { none } -> Cube.create(gl, p, is_selected)
        end;
      scene : engine.scene =
        tmp = get_scene();
        others_scene = List.map(f(false, _), tmp.others.objs);
        selection_scene = Option.switch((the -> [ f(true, the) ]), List.empty, tmp.selection);
        List.append(selection_scene, others_scene);
      ({ eng with ~scene }, scene);
    do match get_mode() with
    | {pick=pos; ~cont} ->
      match which_box(viewbox, pos) with
        | {out} -> void
        | {_YX} as who | {_YZ} as who | {_ZX} as who | {_3D} as who ->
          //do Log.debug("Picking", "in box: '{who}' \t {viewbox}");
          this_viewbox = fetch_box(viewbox, who);
          (pMatrix, s) = drawScene_for_a_viewport(eng, who, this_viewbox, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
          x = (float_of_int(pos.x_px - this_viewbox.x) / float_of_int(this_viewbox.w)) * 2.0 - 1.0;
          y = (float_of_int(pos.y_px - this_viewbox.y) / float_of_int(this_viewbox.h)) * 2.0 - 1.0;
          mvMatrix = Stack.peek(s) ;
          do mat4.multiply(pMatrix, mvMatrix, mvMatrix);
          do mat4.inverse(mvMatrix, mvMatrix);
          g(x, y) =
            vstart = vec4.from_public((x, y, 1.0, 1.0));
            vtmp = vec4.from_public((9.9, 9.9, 9.9, 9.9));
            do mat4.multiplyVec4(mvMatrix, vstart, vtmp);
            vpreres = vec4.to_public(vtmp);
            vres = (vpreres.f1 / vpreres.f4, vpreres.f2 / vpreres.f4, vpreres.f3 / vpreres.f4);
            do Log.debug("Converting coord", "vstart={ vec4.str(vstart) }, \t vres={ vres }");
            vres;
          v2 = g(x, y);
          possible_target =
            pickedColor =
              data = Webgl.Uint8Array.from_int_list(List.init((_->123), 4));
              do Webgl.readPixels(gl, pos.x_px, pos.y_px, 1, 1, Webgl.RGBA(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(data));
              match Webgl.Uint8Array.to_int_list(data) with
              | [r, g, b, _] -> (r, g, b)
              | _ -> error("Picking failure")
              end ;
            do Log.debug("Picking", "Color is: { pickedColor }");
            f =
              (r, g, b) = pickedColor;
              (z -> (z.picking_color == (float_of_int(r) / 255., float_of_int(g) / 255., float_of_int(b) / 255.))) ;
            Option.map((u -> u.id), List.find(f, eng.scene));
          do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
          cont({ mousedown; pos=this_viewbox.clear_near_far(v2); ~possible_target; coord_fixer=Option.none })
          end
    | {normal} ->
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      void
    end ;
    do RequestAnimationFrame.request((_ -> aux(eng)), eng.selector);
    void
    ;
  aux(org_eng)
;

initGL(canvas_sel, width, height, get_scene, mouse_listener) : outcome =
  match WebGLUtils.setupWebGL_with_custom_failure(Dom.of_selection(canvas_sel)) with
  | { ok=context } ->
    mode = Mutable.make({normal});
    is_picking(m) = match m with | { pick=_; cont=_ } -> true | _ -> false end;
    _ =
      recompute_pos(rel_mouse_position_on_page) =
        m_pos = // we transform the pos to be relative to the upper leftcorner of the canvas
          c_pos = Dom.get_offset(canvas_sel);
          rel = rel_mouse_position_on_page;
          { x_px=max(rel.x_px - c_pos.x_px, 0); y_px=max(rel.y_px - c_pos.y_px, 0) };
        // now with gl the origin will be at the lower left corner
        gl_pos = { x_px=min(max(m_pos.x_px,0), width-1); y_px=min(max(height - 1 - m_pos.y_px, 0), height-1) };
        do Log.debug("P", "[({m_pos.x_px},{m_pos.y_px})] {gl_pos.x_px}, {gl_pos.y_px}");
        gl_pos;
      handler_mousedown(e) =
        gl_pos = recompute_pos(e.mouse_position_on_page);
        cont(e) =
          do mode.set({normal});
          mouse_listener(e);
        if not(is_picking(mode.get())) then mode.set({pick=gl_pos; ~cont}) else void;
      _ = Dom.bind(canvas_sel, { mousedown }, handler_mousedown);
      void;
    gl = context;
    eng : engine =
      start = @openrecord({ context=gl; canvas={ selector=canvas_sel; ~width; ~height }; scene=List.empty; selector=canvas_sel });
      start = { start with shaderProgram=initShaders(gl) };
      start = { start with framePickBuffer=initPickBuffer(start) } ;
      { start with static_buffers.repcoords=
        { x=initLineXBuffers(gl, {x}); y=initLineXBuffers(gl, {y}); z=initLineXBuffers(gl, {z}) } };
    //Clear screen and make everything light gray // disabled to show png grid
    //do Webgl.clearColor(gl, 0.875, 0.875, 0.875, 1.0);
    //we should do depth testing so that things drawn behind other
    //things should be hidden by the things in front of them).
    do Webgl.clearDepth(gl, 1.0);
    do Webgl.enable(gl, Webgl.DEPTH_TEST(gl));
    do Webgl.depthFunc(gl, Webgl.LEQUAL(gl));
    do drawScene_and_register(eng, get_scene, mode.get);
    { success }
  | { ~ko } -> { failure=ko }
  end ;

@private type my_custom_shaderProgram = {
  program: Webgl.WebGLProgram;
  vertexPositionAttribute: Webgl.GLint;
  vertexNormalAttribute: Webgl.GLint;
  pMatrixUniform: Webgl.WebGLUniformLocation;
  mvMatrixUniform: Webgl.WebGLUniformLocation;
  nMatrixUniform: Webgl.WebGLUniformLocation;
  ambientColorUniform: Webgl.WebGLUniformLocation;
  lightingDirectionUniform: Webgl.WebGLUniformLocation;
  useLightingUniform: Webgl.WebGLUniformLocation
};

@private type static_buffer = {
  positions: Webgl.WebGLBuffer;
  itemSize: int; numItems: int;
  normals: Webgl.WebGLBuffer
};

@private type engine.scene = list(object);

@private type engine = {
  context: Webgl.Context.private;
  canvas: { selector:dom; width: int; height: int };
  shaderProgram: my_custom_shaderProgram
  static_buffers: { repcoords: { x:static_buffer; y:static_buffer; z:static_buffer } };
  framePickBuffer: Webgl.WebGLFramebuffer;
  scene: engine.scene
  selector: dom
} ;

@client initPickBuffer(eng) =
  gl = eng.context;
  framePickBuffer = Webgl.createFramebuffer(gl);
  renderPickBuffer = Webgl.createRenderbuffer(gl);
  pickTexture = Webgl.createTexture(gl);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.some(pickTexture));
  tex = Webgl.Uint8Array.from_int_list([0, 0, 0]);
  do Webgl.texImage2D(gl, Webgl.TEXTURE_2D(gl), 0, Webgl.RGB(gl), eng.canvas.width, eng.canvas.height, 0, Webgl.RGB(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(tex));
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(framePickBuffer));
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.some(renderPickBuffer));
  do Webgl.renderbufferStorage(gl, Webgl.RENDERBUFFER(gl), Webgl.DEPTH_COMPONENT16(gl), eng.canvas.width, eng.canvas.height);
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.none);

  do Webgl.framebufferTexture2D(gl, Webgl.FRAMEBUFFER(gl), Webgl.COLOR_ATTACHMENT0(gl), Webgl.TEXTURE_2D(gl), pickTexture, 0);
  do Webgl.framebufferRenderbuffer(gl, Webgl.FRAMEBUFFER(gl), Webgl.DEPTH_ATTACHMENT(gl), Webgl.RENDERBUFFER(gl), renderPickBuffer);
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.none);
  framePickBuffer
;

initShaders(gl) =
  f(e, str) =
    shader = Webgl.createShader(gl, e);
    do Webgl.shaderSource(gl, shader, str);
    do Webgl.compileShader(gl, shader);
    shader;
  fragmentShader = f(Webgl.FRAGMENT_SHADER(gl), CustomShaders.shader_fs);
  vertexShader = f(Webgl.VERTEX_SHADER(gl), CustomShaders.shader_vs);
  // TODO getShaderParameter
  shaderProgram = Webgl.createProgram(gl);
  do Webgl.attachShader(gl, shaderProgram, vertexShader);
  do Webgl.attachShader(gl, shaderProgram, fragmentShader);
  do Webgl.linkProgram(gl, shaderProgram);
  // TODO : getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
  do Webgl.useProgram(gl, shaderProgram);
  shaderProgram =
    vertexPositionAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexPosition");
    vertexNormalAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexNormal");
    do Webgl.enableVertexAttribArray(gl, vertexPositionAttribute);
    do Webgl.enableVertexAttribArray(gl, vertexNormalAttribute);
    { program = shaderProgram;
      ~vertexPositionAttribute;
      ~vertexNormalAttribute;
      pMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uPMatrix");
      mvMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uMVMatrix");
      nMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uNMatrix");
      ambientColorUniform = Webgl.getUniformLocation(gl, shaderProgram, "uAmbientColor");
      lightingDirectionUniform = Webgl.getUniformLocation(gl, shaderProgram, "uLightingDirection");
      useLightingUniform = Webgl.getUniformLocation(gl, shaderProgram, "uUseLighting");
    };
  shaderProgram
;

initLineXBuffers(gl, orient) =
  (vertices, vertexNormals) = match orient with
    | {x} -> ([ 0.0, 0.0, 0.0, 5.0, 0.0, 0.0 ], [ 2.5, 0.0, 0.0,        2.5, -1.0, 0.0 ])
    | {y} -> ([ 0.0, 0.0, 0.0, 0.0, 5.0, 0.0 ], [ 0.0, 2.5, 0.0,        -1.0, 2.5, 0.0 ])
    | {z} -> ([ 0.0, 0.0, 0.0, 0.0, 0.0, 5.0 ], [ 0.0, 0.0, 2.5,        0.0, -1.0, 2.5 ])
    end ;
  vertexPositionBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexPositionBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertices)),
    Webgl.STATIC_DRAW(gl));
  vertexNormalBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexNormalBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertexNormals)),
    Webgl.STATIC_DRAW(gl));
  { positions=vertexPositionBuffer; itemSize=3; numItems=2; normals=vertexNormalBuffer }
;

setMatrixUniforms(gl, shaderProgram, pMatrix, mvMatrix) =
  a =
    b = mat4.to_list(pMatrix);
    c = Webgl.Float32Array.from_float_list(b);
    c;
  e =
    f = mat4.to_list(mvMatrix);
    g = Webgl.Float32Array.from_float_list(f);
    g;
  do Webgl.uniformMatrix4fv(gl, shaderProgram.pMatrixUniform, false, a);
  do Webgl.uniformMatrix4fv(gl, shaderProgram.mvMatrixUniform, false, e);
  normalMatrix = mat3.create();
  do mat4.toInverseMat3(mvMatrix, normalMatrix);
  do mat3.transpose(normalMatrix, normalMatrix);
  do Webgl.uniformMatrix3fv(gl, shaderProgram.nMatrixUniform, false, Webgl.Float32Array.from_float_list(mat3.to_list(normalMatrix)));
  void
;

setup_boxes(eng) =
  cnf_x(pos) = { pos with f1=0.0 }; cnf_y(pos) = { pos with f2=0.0 }; cnf_z(pos) = { pos with f3=0.0 };
  g(x:int, y:int, w:int, h:int, clear_near_far) =
    inbox(pos) = (pos.x_px >= x) && (pos.y_px >= y) && (pos.x_px < (w + x)) && (pos.y_px < (h + y));
    { ~x; ~y; ~w; ~h; ~inbox; ~clear_near_far } ;
  compute_left_right(x) = if ((mod(x, 2)) == 0) then
      a = (x / 2);
      ((a, a), 0)
    else
      b = (x / 2);
      ((b, b+1), 0);
  ((w_l, w_r), e_w) = compute_left_right(eng.canvas.width);
  ((h_u, h_d), e_h) = compute_left_right(eng.canvas.height);
  { _YX=g(0, h_d+e_h, w_l, h_u, cnf_z); _YZ=g(w_l+e_w, h_d+e_h, w_r, h_u, cnf_x);
    _ZX=g(0, 0, w_l, h_d, cnf_y);       _3D=g(w_l+e_w, 0, w_r, h_d, cnf_y) }
;

which_box(b, pos) =
  if b._YX.inbox(pos) then {_YX}
  else if b._YZ.inbox(pos) then {_YZ}
  else if b._ZX.inbox(pos) then {_ZX}
  else if b._3D.inbox(pos) then {_3D}
  else {out}
;

fetch_box(b, who) = match who with
  | {_YX} -> b._YX
  | {_YZ} -> b._YZ
  | {_ZX} -> b._ZX
  | {_3D} -> b._3D
  end ;

drawScene_for_a_viewport(eng, who, viewport, eye, up, scene, mode) =
  gl = eng.context; shaderProgram = eng.shaderProgram; repcoords = eng.static_buffers.repcoords;
  do Webgl.viewport(gl, viewport.x, viewport.y, viewport.w, viewport.h);
  pMatrix =
    tmp_pMatrix = mat4.create();
    tmp_x = Float.of_int(viewport.w / 40)
    tmp_y = Float.of_int(viewport.h / 40)
    match who with
    | {_YX} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      tmp_pMatrix
    | {_YZ} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      mat4.rotateY(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_ZX} ->
      do mat4.ortho(-tmp_x, tmp_x, -tmp_y, tmp_y, -10., 10., tmp_pMatrix);
      mat4.rotateX(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_3D} ->
      do mat4.perspective(45., float_of_int(eng.canvas.width) / float_of_int(eng.canvas.height), 0.1, 100.0, tmp_pMatrix);
      c = mat4.create() ;
      do mat4.lookAt(vec3.from_public(eye), vec3.from_public((0.0, 0.0, 0.0)), vec3.from_public(up), c);
      do mat4.multiply(tmp_pMatrix, c, tmp_pMatrix);
      tmp_pMatrix
    end ;
  mvMatrix =
    tmp_mvMatrix = mat4.create();
    do mat4.identity(tmp_mvMatrix);
    Stack.push(Stack.create(), tmp_mvMatrix);
  do setMatrixUniforms(gl, shaderProgram, pMatrix, Stack.peek(mvMatrix));
  draw_rep(r, g, b, rep) =
    do Webgl.uniform3f(gl, shaderProgram.ambientColorUniform, r, g, b);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.positions);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexPositionAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.normals);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexNormalAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.drawArrays(gl, Webgl.LINES(gl), 0, rep.numItems);
    void ;

  _ =
    match mode with
    | {normal} ->
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false
      do draw_rep(1.0, 0.0, 0.0, repcoords.x);
      do draw_rep(0.0, 1.0, 0.0, repcoords.y);
      do draw_rep(0.0, 0.0, 1.0, repcoords.z);
      do match who with
        | {_3D} ->
          do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 1); // 1 = true
          Webgl.uniform3f(gl, shaderProgram.lightingDirectionUniform, 0.85, 0.8, 0.75)
        | _ -> void end;
      List.iter((object -> display(eng, pMatrix, mvMatrix, object, false)), scene)
    | {pick} ->
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(eng.framePickBuffer));
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false;
      do List.iter((object -> display(eng, pMatrix, mvMatrix, object, true)), scene);
      void
    end ;

  (pMatrix, mvMatrix)
;

@private drawScene_and_register(org_eng, get_scene : (->Scene.Client.scene), get_mode) =
  viewbox = setup_boxes(org_eng) ;
  rec aux(eng:engine) =
    gl = eng.context;
    (eng, scene) =
      f(is_selected, p) =
        match List.find((z_in_mem -> z_in_mem.id == p.id), eng.scene) with
        | { some=in_mem } -> { in_mem with position=p.cube; ~is_selected; color=p.color }
        | { none } -> Cube.create(gl, p, is_selected)
        end;
      scene : engine.scene =
        tmp = get_scene();
        others_scene = List.map(f(false, _), tmp.others.objs);
        selection_scene = Option.switch((the -> [ f(true, the) ]), List.empty, tmp.selection);
        List.append(selection_scene, others_scene);
      ({ eng with ~scene }, scene);
    do match get_mode() with
    | {pick=pos; ~cont} ->
      match which_box(viewbox, pos) with
        | {out} -> void
        | {_YX} as who | {_YZ} as who | {_ZX} as who | {_3D} as who ->
          //do Log.debug("Picking", "in box: '{who}' \t {viewbox}");
          this_viewbox = fetch_box(viewbox, who);
          (pMatrix, s) = drawScene_for_a_viewport(eng, who, this_viewbox, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
          x = (float_of_int(pos.x_px - this_viewbox.x) / float_of_int(this_viewbox.w)) * 2.0 - 1.0;
          y = (float_of_int(pos.y_px - this_viewbox.y) / float_of_int(this_viewbox.h)) * 2.0 - 1.0;
          mvMatrix = Stack.peek(s) ;
          do mat4.multiply(pMatrix, mvMatrix, mvMatrix);
          do mat4.inverse(mvMatrix, mvMatrix);
          g(x, y) =
            vstart = vec4.from_public((x, y, 1.0, 1.0));
            vtmp = vec4.from_public((9.9, 9.9, 9.9, 9.9));
            do mat4.multiplyVec4(mvMatrix, vstart, vtmp);
            vpreres = vec4.to_public(vtmp);
            vres = (vpreres.f1 / vpreres.f4, vpreres.f2 / vpreres.f4, vpreres.f3 / vpreres.f4);
            do Log.debug("Converting coord", "vstart={ vec4.str(vstart) }, \t vres={ vres }");
            vres;
          v2 = g(x, y);
          data = Webgl.Uint8Array.from_int_list(List.init((_->123), 4));
          do Webgl.readPixels(gl, pos.x_px, pos.y_px, 1, 1, Webgl.RGBA(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(data));
          pickedColor = match Webgl.Uint8Array.to_int_list(data) with
            | [r, g, b, _] -> (r, g, b)
            | _ -> error("Picking failure")
            end ;
          do Log.debug("Picking", "Color is: { pickedColor }");
          //do jlog("Color is: { pickedColor }; v={ vec3.str(v) }");
          possible_target =
            (r, g, b) = pickedColor;
            f(z) = (z.picking_color == (float_of_int(r) / 255., float_of_int(g) / 255., float_of_int(b) / 255.)) ;
            Option.map((u -> u.id), List.find(f, eng.scene));
          do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
          cont({ mousedown; pos=this_viewbox.clear_near_far(v2); ~possible_target; coord_fixer=Option.none })
          end
    | {normal} ->
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      void
    end ;
    do RequestAnimationFrame.request((_ -> aux(eng)), eng.selector);
    void
    ;
  aux(org_eng)
;

initGL(canvas_sel, width, height, get_scene, mouse_listener) : outcome =
  match WebGLUtils.setupWebGL_with_custom_failure(Dom.of_selection(canvas_sel)) with
  | { ok=context } ->
    mode = Mutable.make({normal});
    is_picking(m) = match m with | { pick=_; cont=_ } -> true | _ -> false end;
    _ =
      recompute_pos(rel_mouse_position_on_page) =
        m_pos = // we transform the pos to be relative to the upper leftcorner of the canvas
          c_pos = Dom.get_offset(canvas_sel);
          rel = rel_mouse_position_on_page;
          { x_px=max(rel.x_px - c_pos.x_px, 0); y_px=max(rel.y_px - c_pos.y_px, 0) };
        // now with gl the origin will be at the lower left corner
        gl_pos = { x_px=min(max(m_pos.x_px,0), width-1); y_px=min(max(height - 1 - m_pos.y_px, 0), height-1) };
        do Log.debug("P", "[({m_pos.x_px},{m_pos.y_px})] {gl_pos.x_px}, {gl_pos.y_px}");
        gl_pos;
      handler_mousedown(e) =
        gl_pos = recompute_pos(e.mouse_position_on_page);
        cont(e) =
          do mode.set({normal});
          mouse_listener(e);
        if not(is_picking(mode.get())) then mode.set({pick=gl_pos; ~cont}) else void;
      _ = Dom.bind(canvas_sel, { mousedown }, handler_mousedown);
      void;
    gl = context;
    eng : engine =
      start = @openrecord({ context=gl; canvas={ selector=canvas_sel; ~width; ~height }; scene=List.empty; selector=canvas_sel });
      start = { start with shaderProgram=initShaders(gl) };
      start = { start with framePickBuffer=initPickBuffer(start) } ;
      { start with static_buffers.repcoords=
        { x=initLineXBuffers(gl, {x}); y=initLineXBuffers(gl, {y}); z=initLineXBuffers(gl, {z}) } };
    //Clear screen and make everything light gray // disabled to show png grid
    //do Webgl.clearColor(gl, 0.875, 0.875, 0.875, 1.0);
    //we should do depth testing so that things drawn behind other
    //things should be hidden by the things in front of them).
    do Webgl.clearDepth(gl, 1.0);
    do Webgl.enable(gl, Webgl.DEPTH_TEST(gl));
    do Webgl.depthFunc(gl, Webgl.LEQUAL(gl));
    do drawScene_and_register(eng, get_scene, mode.get);
    { success }
  | { ~ko } -> { failure=ko }
  end ;


adding a state

adding a state

import stdlib.widgets.colorpicker
import stdlib.widgets.core

type GuiModeler.t = {
  modeler: Modeler.modeler;
  subjects: {
    tool: subject(Modeler.tool);
    selection: { this: subject(option(Scene.objects)); color: subject(ColorFloat.color) }
    };
  last_coord_fixer: option(Dom.dimensions -> vec3)
  width: int; height: int
} ;

@client GuiModeler = {{

  Sync = {{
    on_message(state : GuiModeler.t, message) =
      set_modeler(modeler) = { set={ state with ~modeler } } ;
      set(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler } };
      match message : Central.Modelers.sync.message with
      | {load=a_scene} ->
        modeler = Modeler.load(`Scene.Client`.load(a_scene, state.modeler.client_id), state.modeler.address, state.modeler.client_id, float_of_int(state.height) / float_of_int(state.width));
        subjects =
          { state.subjects with selection={
              this=Observable.change_state(modeler.scene.selection, state.subjects.selection.this);
              color=
                tmp = Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection);
                Observable.change_state(tmp , state.subjects.selection.color) } };
        set({ ~subjects; ~modeler })
      | { write_patch; ~patch } ->
        modeler = Modeler.write_patch(state.modeler, patch);
        set_modeler(modeler)
      end ;
  }}

  empty(scene_url, client_id, width, height) : GuiModeler.t =
    modeler = Modeler.empty(scene_url, client_id, float_of_int(height) / float_of_int(width));
    subjects = { tool=Observable.make(modeler.tool); selection={ this=Observable.make(modeler.scene.selection); color=Observable.make( Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection) ) } };
    { ~modeler; ~subjects; last_coord_fixer=Option.none; ~width; ~height };

  @private on_message(state : GuiModeler.t, message) =
    _set_modeler(modeler) = { set={ state with ~modeler } } ;
    _set_subjects(subjects) = { set={ state with ~subjects } } ;
    set(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler } };
    _set_with_last(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler; last_coord_fixer=new_state.last_coord_fixer } };
    send_opatch(opatch) =
      m(patch) = { apply_patch; ~patch; address=state.modeler.address };
      Option.iter((p -> Session.send(central_modelers, m(p))), opatch);
    reset_subjects(modeler) =
      subjects = { state.subjects with selection={ this=Observable.change_state(modeler.scene.selection, state.subjects.selection.this);
                                                   color=Observable.change_state( Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection) , state.subjects.selection.color) } };
      { state with ~subjects; ~modeler };
    match message with
    | {click_on_scene; ~where; ~possible_target; ~last_coord_fixer} ->
      (modeler, opatch) = Modeler.tool_use(state.modeler, where, possible_target);
      do send_opatch(opatch);
      if Observable.get_state(state.subjects.selection.this) == modeler.scene.selection then
        { set={ state with ~modeler; ~last_coord_fixer } }
      else
        state = { reset_subjects(modeler) with ~last_coord_fixer };
        set(state)
    | {modeler_change_tool=new_tool} ->
      modeler = Modeler.tool_change(state.modeler, new_tool);
      subjects = { state.subjects with tool=Observable.change_state(new_tool, state.subjects.tool) };
      set({ ~subjects; ~modeler })
    | {modeler_change_scene_selection_color; ~new_color} ->
      (modeler, opatch) = Modeler.scene_change_selection_color(state.modeler, new_color);
      do send_opatch(opatch);
      subjects = { state.subjects with selection.color=Observable.change_state(new_color, state.subjects.selection.color) };
      set({ ~subjects; ~modeler})
    | {modeler_apply_possible_move; ~where; ~switch } ->
      (modeler, opatch) = Modeler.do_possible_move(state.modeler, where, switch);
      do send_opatch(opatch);
      { set={ state with ~modeler } }
    | {modeler_delete_scene_selection} ->
      (modeler, opatch) = Modeler.scene_delete_selection(state.modeler);
      do send_opatch(opatch);
      set(reset_subjects(modeler))
    end ;

  setup_menu(parent_sel, channel, s_tool) : void =
    f(some_tool) = match some_tool with
      | {selection} -> (Select, Cube)
      | {add_cube} -> (Select, Cube)
      end ;
    (id_a, id_b) = (Random.string(7), Random.string(7));
    on_tool_change =
      then_do(new_tool) =
        (text_a, text_b) = f(new_tool);
        Dom.transform([#{id_a}<- text_a, #{id_b}<- text_b]);
      { si=(-> not(Dom.is_empty(#{id_a})) && not(Dom.is_empty(#{id_b}))); ~then_do; else_autoclean };
    do Observable.register(on_tool_change, s_tool);
    menu =
      s(x) = (_ -> Session.send(channel, {modeler_change_tool=x}));

;
    ignore(Dom.put_at_start(parent_sel, Dom.of_xhtml(menu)));

  setup_selection_view(parent_sel, channel, s_selection) : void =
    id = Random.string(7);
    do
      f(some_selection) = match some_selection with
        | {none} -> <></>
        | {some=_} ->
          id = Random.string(7);
          config =
            style = { WColorpicker.default_config_style with preview=WStyler.make_style(css { height:10px; width:10px; border:1px double black;}) };
            s(a_color) =
              Session.send(channel, {modeler_change_scene_selection_color; new_color=ColorFloat.from_Color_color(a_color)});
            { WColorpicker.default_config with on_select=s; ~style };
          do
            on_sel_color_change =
              then_do(f_new_color) =
                new_color = ColorFloat.to_Color_color(f_new_color);
                WColorpicker.set_color(id, config, new_color, false);
              { si=(->not(Dom.is_empty(#{id}))); ~then_do; else_autoclean };
            Observable.register(on_sel_color_change, s_selection.color);

            Cube

Color:
{ WColorpicker.html(id, config) }

 Session.send(channel, {modeler_delete_scene_selection})}>Remove me

        end ;
      on_selection_change =
        then_do(new_selection) = Dom.transform([#{id}<- f(new_selection)]);
        { si=(->not(Dom.is_empty(#{id}))); ~then_do; else_autoclean };
      Observable.register(on_selection_change, s_selection.this);
    sel =

;
    ignore(Dom.put_at_end(parent_sel, Dom.of_xhtml(sel)));

  init(scene_url, client_id, parent_sel:dom, width, height) : void =
    id_canvas_canvas = "canvas_canvas" ;
    fail_msg =
      <>It seems that your browser and/or graphics card are incompatible with Webgl.Learn a little more about webgl support</> ;
    and_do(_) =
      (channel, get_scene, get_subjects, get_camera_setting) =
        (channel, sync_channel, get_state) = SessionExt.make_2_side(empty(scene_url, client_id, width, height), on_message, Sync.on_message);
        do Session.send(central_modelers, {register; ~scene_url; ~sync_channel; ~client_id});
        (channel, (-> get_state().modeler.scene), (->get_state().subjects), (->get_state().modeler.views)) ;
      support_gpu_picking = Mutable.make(Option.none);
      lock_mouse_event = Mutable.make(false);
      mouse_listener =
        on_message_mouse_listener(state_mouse, msg, my_channel) =
          match msg with
          | { mousedown; event=_; ~abs_full_pos; ~gl_pos } ->
            f(gpu_picker_regsiter) =
              do lock_mouse_event.set(true);
              sub(possible_target) =
                do Session.send(channel, {click_on_scene; where=gl_pos; ~possible_target; last_coord_fixer=Option.none});
                Session.send(my_channel, { _internal; done_down });
              gpu_picker_regsiter((abs_full_pos, sub)) ;
            do Option.iter(f, support_gpu_picking.get());
            { set={ running_down=List.empty } }
          | { mouseup; event=_; ~gl_pos; ~switch } ->
            f() =
              msg = {modeler_apply_possible_move; where=gl_pos; ~switch };
              Session.send(channel, msg);
            match state_mouse with
            | { nothing } -> do f(); { unchanged }
            | { running_down=l } ->
              { set={ running_down=List.cons(f, l) } }
            end
          | { _internal; done_down } -> match state_mouse with
            | { nothing } -> do Log.debug("", ""); { unchanged }
            | { running_down=l } -> do List.iter((f -> f()), l); { set={ nothing } }
            end
          end;
        channel_mouse_listener = Session.make_own({nothing}, on_message_mouse_listener);
        (msg -> Session.send(channel_mouse_listener, msg));
      res = initGL(#{id_canvas_canvas}, width, height, get_scene, get_camera_setting, mouse_listener, support_gpu_picking) ;
      if Outcome.is_failure(res) then ignore(Dom.put_replace(parent_sel, Dom.of_xhtml(fail_msg)))
      else
        the_subjects = get_subjects();
        do setup_menu(parent_sel, channel, the_subjects.tool);
        setup_selection_view(parent_sel, channel, the_subjects.selection);
    base =

<canvas width={width} height={height} id=#{id_canvas_canvas} onready={and_do} ></canvas>
;
    ignore(Dom.put_inside(parent_sel, Dom.of_xhtml(base)));

}}

import stdlib.widgets.colorpicker
import stdlib.widgets.core

type GuiModeler.t = {
  modeler: Modeler.modeler;
  subjects: {
    tool: subject(Modeler.tool);
    selection: { this: subject(option(Scene.objects)); color: subject(ColorFloat.color) }
    };
  last_coord_fixer: option(Dom.dimensions -> vec3)
  width: int; height: int
} ;

@client GuiModeler = {{

  Sync = {{
    on_message(state : GuiModeler.t, message) =
      set_modeler(modeler) = { set={ state with ~modeler } } ;
      set(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler } };
      match message : Central.Modelers.sync.message with
      | {load=a_scene} ->
        modeler = Modeler.load(`Scene.Client`.load(a_scene, state.modeler.client_id), state.modeler.address, state.modeler.client_id, float_of_int(state.height) / float_of_int(state.width));
        subjects =
          { state.subjects with selection={
              this=Observable.change_state(modeler.scene.selection, state.subjects.selection.this);
              color=
                tmp = Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection);
                Observable.change_state(tmp , state.subjects.selection.color) } };
        set({ ~subjects; ~modeler })
      | { write_patch; ~patch } ->
        modeler = Modeler.write_patch(state.modeler, patch);
        set_modeler(modeler)
      end ;
  }}

  empty(scene_url, client_id, width, height) : GuiModeler.t =
    modeler = Modeler.empty(scene_url, client_id, float_of_int(height) / float_of_int(width));
    subjects = { tool=Observable.make(modeler.tool); selection={ this=Observable.make(modeler.scene.selection); color=Observable.make( Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection) ) } };
    { ~modeler; ~subjects; last_coord_fixer=Option.none; ~width; ~height };

  @private on_message(state : GuiModeler.t, message) =
    _set_modeler(modeler) = { set={ state with ~modeler } } ;
    _set_subjects(subjects) = { set={ state with ~subjects } } ;
    set(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler } };
    _set_with_last(new_state) = { set={ state with subjects=new_state.subjects; modeler=new_state.modeler; last_coord_fixer=new_state.last_coord_fixer } };
    send_opatch(opatch) =
      m(patch) = { apply_patch; ~patch; address=state.modeler.address };
      Option.iter((p -> Session.send(central_modelers, m(p))), opatch);
    reset_subjects(modeler) =
      subjects = { state.subjects with selection={ this=Observable.change_state(modeler.scene.selection, state.subjects.selection.this);
                                                   color=Observable.change_state( Option.switch((o->o.color), ColorFloat.random(), modeler.scene.selection) , state.subjects.selection.color) } };
      { state with ~subjects; ~modeler };
    match message with
    | {click_on_scene; ~where; ~possible_target; ~last_coord_fixer} ->
      (modeler, opatch) = Modeler.tool_use(state.modeler, where, possible_target);
      do send_opatch(opatch);
      if Observable.get_state(state.subjects.selection.this) == modeler.scene.selection then
        { set={ state with ~modeler; ~last_coord_fixer } }
      else
        state = { reset_subjects(modeler) with ~last_coord_fixer };
        set(state)
    | {modeler_change_tool=new_tool} ->
      modeler = Modeler.tool_change(state.modeler, new_tool);
      subjects = { state.subjects with tool=Observable.change_state(new_tool, state.subjects.tool) };
      set({ ~subjects; ~modeler })
    | {modeler_change_scene_selection_color; ~new_color} ->
      (modeler, opatch) = Modeler.scene_change_selection_color(state.modeler, new_color);
      do send_opatch(opatch);
      subjects = { state.subjects with selection.color=Observable.change_state(new_color, state.subjects.selection.color) };
      set({ ~subjects; ~modeler})
    | {modeler_apply_possible_move; ~where; ~switch } ->
      (modeler, opatch) = Modeler.do_possible_move(state.modeler, where, switch);
      do send_opatch(opatch);
      { set={ state with ~modeler } }
    | {modeler_delete_scene_selection} ->
      (modeler, opatch) = Modeler.scene_delete_selection(state.modeler);
      do send_opatch(opatch);
      set(reset_subjects(modeler))
    end ;

  setup_menu(parent_sel, channel, s_tool) : void =
    f(some_tool) = match some_tool with
      | {selection} -> (Select, Cube)
      | {add_cube} -> (Select, Cube)
      end ;
    (id_a, id_b) = (Random.string(7), Random.string(7));
    on_tool_change =
      then_do(new_tool) =
        (text_a, text_b) = f(new_tool);
        Dom.transform([#{id_a}<- text_a, #{id_b}<- text_b]);
      { si=(-> not(Dom.is_empty(#{id_a})) && not(Dom.is_empty(#{id_b}))); ~then_do; else_autoclean };
    do Observable.register(on_tool_change, s_tool);
    menu =
      s(x) = (_ -> Session.send(channel, {modeler_change_tool=x}));

;
    ignore(Dom.put_at_start(parent_sel, Dom.of_xhtml(menu)));

  setup_selection_view(parent_sel, channel, s_selection) : void =
    id = Random.string(7);
    do
      f(some_selection) = match some_selection with
        | {none} -> <></>
        | {some=_} ->
          id = Random.string(7);
          config =
            style = { WColorpicker.default_config_style with preview=WStyler.make_style(css { height:10px; width:10px; border:1px double black;}) };
            s(a_color) =
              Session.send(channel, {modeler_change_scene_selection_color; new_color=ColorFloat.from_Color_color(a_color)});
            { WColorpicker.default_config with on_select=s; ~style };
          do
            on_sel_color_change =
              then_do(f_new_color) =
                new_color = ColorFloat.to_Color_color(f_new_color);
                WColorpicker.set_color(id, config, new_color, false);
              { si=(->not(Dom.is_empty(#{id}))); ~then_do; else_autoclean };
            Observable.register(on_sel_color_change, s_selection.color);

            Cube

Color:
{ WColorpicker.html(id, config) }

 Session.send(channel, {modeler_delete_scene_selection})}>Remove me

        end ;
      on_selection_change =
        then_do(new_selection) = Dom.transform([#{id}<- f(new_selection)]);
        { si=(->not(Dom.is_empty(#{id}))); ~then_do; else_autoclean };
      Observable.register(on_selection_change, s_selection.this);
    sel =

;
    ignore(Dom.put_at_end(parent_sel, Dom.of_xhtml(sel)));

  init(scene_url, client_id, parent_sel:dom, width, height) : void =
    id_canvas_canvas = "canvas_canvas" ;
    fail_msg =
      <>It seems that your browser and/or graphics card are incompatible with Webgl.Learn a little more about webgl support</> ;
    and_do(_) =
      (channel, get_scene, get_subjects, get_camera_setting) =
        (channel, sync_channel, get_state) = SessionExt.make_2_side(empty(scene_url, client_id, width, height), on_message, Sync.on_message);
        do Session.send(central_modelers, {register; ~scene_url; ~sync_channel; ~client_id});
        (channel, (-> get_state().modeler.scene), (->get_state().subjects), (->get_state().modeler.views)) ;
      support_gpu_picking = Mutable.make(Option.none);
      lock_mouse_event = Mutable.make(false);
      on_message_mouse_listener(msg) =
        match msg with
        | { mousedown; event=_; ~abs_full_pos; ~gl_pos } ->
          f(gpu_picker_regsiter) =
            do lock_mouse_event.set(true);
            gpu_picker_regsiter((abs_full_pos, (possible_target -> do Session.send(channel, {click_on_scene; where=gl_pos; ~possible_target; last_coord_fixer=Option.none}); lock_mouse_event.set(false)))) ;
          do Option.switch(f, void, support_gpu_picking.get());
          { continue }
        | { mouseup; event=_; ~gl_pos; ~switch } ->
          msg = {modeler_apply_possible_move; where=gl_pos; ~switch };
          do Session.send(channel, msg);
          { continue }
        end ;
      mouse_listener =
        channel_mouse_listener = Session.make_stateless(on_message_mouse_listener);
        (msg -> Session.send(channel_mouse_listener, msg));
      res = initGL(#{id_canvas_canvas}, width, height, get_scene, get_camera_setting, mouse_listener, support_gpu_picking) ;
      if Outcome.is_failure(res) then ignore(Dom.put_replace(parent_sel, Dom.of_xhtml(fail_msg)))
      else
        the_subjects = get_subjects();
        do setup_menu(parent_sel, channel, the_subjects.tool);
        setup_selection_view(parent_sel, channel, the_subjects.selection);
    base =

<canvas width={width} height={height} id=#{id_canvas_canvas} onready={and_do} ></canvas>
;
    ignore(Dom.put_inside(parent_sel, Dom.of_xhtml(base)));

}}


code factorisation

code factorisation

type Scene.objects = { cube: (float, float, float); id: hidden_id; color: ColorFloat.color } ;

type Scene.scene = { objs: list(Scene.objects); CPF: Fresh.next(patch_id) };
type Scene.command = { add_cube; where: {x: float; y: float; z:float } } / { change_color; id: hidden_id; new_color: ColorFloat.color };
type Scene.patch = { pid: patch_id;  command: Scene.command };

type Scene.Client.command = { add_cube; where: {x: float; y: float; z:float } } / { selection_change_color; new_color: ColorFloat.color };

type Scene.Client.scene = { selection: option(Scene.objects); others: Scene.scene };

type Modeler.tool = {selection} / {add_cube} ;

type Modeler.modeler = {
  address: string;
  scene: Scene.Client.scene;
  tool: Modeler.tool;
} ;

Scene = {{
  empty(client_id) : Scene.scene =
    c(pos) = {cube=pos; id=CHF(); color=ColorFloat.random()};
    { objs=[ c((0.0, 0.0, -3.0)), c((3.0, 0.0, 0.0)), c((6.0, 0.0, 0.0)) ]; CPF=build_CPF(client_id) };

  find_object(scene : Scene.scene, target_id) : option(Scene.objects) = List.find((z -> z.id == target_id), scene.objs);
  extract_object(scene, target_id) : (option(Scene.objects), Scene.scene) =
    (target, rest) = List.extract_p((z -> z.id == target_id), scene.objs);
    (target, { scene with objs=rest });
  extract_object_by_pos(scene, nth) : (option(Scene.objects), Scene.scene) =
    (target, rest) = List.extract(nth, scene.objs);
    (target, { scene with objs=rest });
  add_object(scene, object) : Scene.scene = { scene with objs=List.cons(object, scene.objs) };
  reinject_object(scene, oobject : option(Scene.objects)) : Scene.scene = Option.switch((an_o -> add_object(scene, an_o)), scene, oobject);

  apply_command(scene, command : Scene.command) : Scene.scene = match command with
    | {add_cube; ~where} -> add_object(scene, {cube=(where.x, where.y, where.z); id=CHF(); color=ColorFloat.random()})
    | {change_color; ~id; ~new_color} ->
      (otarget, scene) = extract_object(scene, id);
      f(an_o) = add_object(scene, { an_o with color=new_color });
      Option.switch(f, scene, otarget)
    end ;

  apply_patch(scene, patch : Scene.patch) : Scene.scene = apply_command(scene, patch.command) ;
  apply_patchs(scene, patchs : list(Scene.patch)) : Scene.scene = List.fold((p, acc -> apply_patch(acc, p)), patchs, scene);

  selection_change(scene, possible_target) : Scene.Client.scene =
    match (possible_target, scene.selection) with
    | ({none}, {none}) -> scene
    | ({none}, {~some}) -> { selection=Option.none; others=Scene.add_object(scene.others, some) }
    | ({~some}, osel) ->
      //we put back the sel with others
      others = Option.switch((sel -> add_object(scene.others, sel)), scene.others, osel);
      //we retrieve the new sel
      (new_sel, others) = extract_object(others, some);
      do if Option.is_none(new_sel) then Log.error("Scene", "a selection failed to find the corresponding object");
      { selection=new_sel; ~others }
    end ;

}} ;

`Scene.Client` = {{

  load(scene : Scene.scene) : Scene.Client.scene =
    (selection, others) = Scene.extract_object_by_pos(scene, 0);
    { ~selection; ~others };

  empty() : Scene.Client.scene = load(Scene.empty(Random.int(99)));

  command_to_scene_patch(scene, cmd : Scene.Client.command) : option(Scene.patch) = match cmd with
    | { add_cube; ... } as command -> Option.some({ pid=scene.others.CPF(); ~command })
    | { selection_change_color; ~new_color } ->
      f(sel) = { pid=scene.others.CPF(); command={ change_color; id=sel.id ; ~new_color } };
      Option.map(f, scene.selection)
    end;

  apply_command(scene, command : Scene.Client.command) : Scene.Client.scene =
    Option.switch((p -> { scene with others=Scene.apply_patch(scene.others, p) }), scene, command_to_scene_patch(scene, command));

  others_add_cube(scene, where) : Scene.Client.scene = apply_command(scene, {add_cube; ~where});

  selection_change_color(scene, new_color) : Scene.Client.scene = apply_command(scene, {selection_change_color; ~new_color});

}} ;

Modeler = {{
  empty(scene_url) : Modeler.modeler = { address=scene_url; scene=`Scene.Client`.empty(); tool={selection} } ;

  tool_use(modeler, where, possible_target)  : Modeler.modeler =
    do Log.info("Modeler", "using tool at ({where}) perhaps on the target: '{possible_target}' with tool: '{modeler.tool}'");
    match modeler.tool with
    | {add_cube} -> { modeler with scene=`Scene.Client`.others_add_cube(modeler.scene, where) }
    | {selection} -> { modeler with scene=Scene.selection_change(modeler.scene, possible_target) }
    end ;

  tool_change(modeler, new_tool) : Modeler.modeler = { modeler with tool=new_tool };

  scene_change_selection_color(modeler, new_color) : Modeler.modeler = { modeler with scene=`Scene.Client`.selection_change_color(modeler.scene, new_color) };

}} ;

type Scene.objects = { cube: (float, float, float); id: hidden_id; color: ColorFloat.color } ;

type Scene.scene = { objs: list(Scene.objects); CPF: Fresh.next(patch_id) };
type Scene.command = { add_cube; where: {x: float; y: float; z:float } } / { change_color; id: hidden_id; new_color: ColorFloat.color };
type Scene.patch = { pid: patch_id;  command: Scene.command };

type Scene.Client.command = { add_cube; where: {x: float; y: float; z:float } } / { selection_change_color; new_color: ColorFloat.color };

type Scene.Client.scene = { selection: option(Scene.objects); others: Scene.scene };

type Modeler.tool = {selection} / {add_cube} ;

type Modeler.modeler = {
  address: string;
  scene: Scene.Client.scene;
  tool: Modeler.tool;
} ;

Scene = {{
  empty(client_id) : Scene.scene =
    c(pos) = {cube=pos; id=CHF(); color=ColorFloat.random()};
    { objs=[ c((0.0, 0.0, -3.0)), c((3.0, 0.0, 0.0)), c((6.0, 0.0, 0.0)) ]; CPF=build_CPF(client_id) };

  find_object(scene : Scene.scene, target_id) : option(Scene.objects) = List.find((z -> z.id == target_id), scene.objs);
  extract_object(scene, target_id) : (option(Scene.objects), Scene.scene) =
    (target, rest) = List.extract_p((z -> z.id == target_id), scene.objs);
    (target, { scene with objs=rest });
  extract_object_by_pos(scene, nth) : (option(Scene.objects), Scene.scene) =
    (target, rest) = List.extract(nth, scene.objs);
    (target, { scene with objs=rest });
  add_object(scene, object) : Scene.scene = { scene with objs=List.cons(object, scene.objs) };
  reinject_object(scene, oobject : option(Scene.objects)) : Scene.scene = Option.switch((an_o -> add_object(scene, an_o)), scene, oobject);

  apply_command(scene, command : Scene.command) : Scene.scene = match command with
    | {add_cube; ~where} -> add_object(scene, {cube=(where.x, where.y, where.z); id=CHF(); color=ColorFloat.random()})
    | {change_color; ~id; ~new_color} ->
      (otarget, scene) = extract_object(scene, id);
      f(an_o) = add_object(scene, { an_o with color=new_color });
      Option.switch(f, scene, otarget)
    end ;

  apply_patch(scene, patch : Scene.patch) : Scene.scene = apply_command(scene, patch.command) ;
  apply_patchs(scene, patchs : list(Scene.patch)) : Scene.scene = List.fold((p, acc -> apply_patch(acc, p)), patchs, scene);

  selection_change(scene, possible_target) : Scene.Client.scene =
    match (possible_target, scene.selection) with
    | ({none}, {none}) -> scene
    | ({none}, {~some}) -> { selection=Option.none; others=Scene.add_object(scene.others, some) }
    | ({~some}, osel) ->
      //we put back the sel with others
      others = Option.switch((sel -> add_object(scene.others, sel)), scene.others, osel);
      //we retrieve the new sel
      (new_sel, others) = extract_object(others, some);
      do if Option.is_none(new_sel) then Log.error("Scene", "a selection failed to find the corresponding object");
      { selection=new_sel; ~others }
    end ;

}} ;

`Scene.Client` = {{

  load(scene : Scene.scene) : Scene.Client.scene =
    (selection, others) = Scene.extract_object_by_pos(scene, 0);
    { ~selection; ~others };

  empty() : Scene.Client.scene = load(Scene.empty(Random.int(99)));

  command_to_scene_patch(scene, cmd : Scene.Client.command) : option(Scene.patch) = match cmd with
    | { add_cube; ... } as command -> Option.some({ pid=scene.others.CPF(); ~command })
    | { selection_change_color; ~new_color } ->
      f(sel) = { pid=scene.others.CPF(); command={ change_color; id=sel.id ; ~new_color } };
      Option.map(f, scene.selection)
    end;

  others_add_cube(scene, where) : Scene.Client.scene =
    Option.switch((p -> { scene with others=Scene.apply_patch(scene.others, p) }), scene, command_to_scene_patch(scene, {add_cube; ~where}));

  selection_change_color(scene, new_color) : Scene.Client.scene =
    Option.switch((p -> { scene with others=Scene.apply_patch(scene.others, p) }), scene, command_to_scene_patch(scene, {selection_change_color; ~new_color}));

}} ;

Modeler = {{
  empty(scene_url) : Modeler.modeler = { address=scene_url; scene=`Scene.Client`.empty(); tool={selection} } ;

  tool_use(modeler, where, possible_target)  : Modeler.modeler =
    do Log.info("Modeler", "using tool at ({where}) perhaps on the target: '{possible_target}' with tool: '{modeler.tool}'");
    match modeler.tool with
    | {add_cube} -> { modeler with scene=`Scene.Client`.others_add_cube(modeler.scene, where) }
    | {selection} -> { modeler with scene=Scene.selection_change(modeler.scene, possible_target) }
    end ;

  tool_change(modeler, new_tool) : Modeler.modeler = { modeler with tool=new_tool };

  scene_change_selection_color(modeler, new_color) : Modeler.modeler = { modeler with scene=`Scene.Client`.selection_change_color(modeler.scene, new_color) };

}} ;


removing the mutable bank

removing the mutable bank

@private type my_custom_shaderProgram = {
  program: Webgl.WebGLProgram;
  vertexPositionAttribute: Webgl.GLint;
  vertexNormalAttribute: Webgl.GLint;
  pMatrixUniform: Webgl.WebGLUniformLocation;
  mvMatrixUniform: Webgl.WebGLUniformLocation;
  nMatrixUniform: Webgl.WebGLUniformLocation;
  ambientColorUniform: Webgl.WebGLUniformLocation;
  lightingDirectionUniform: Webgl.WebGLUniformLocation;
  useLightingUniform: Webgl.WebGLUniformLocation
};

@private type static_buffer = {
  positions: Webgl.WebGLBuffer;
  itemSize: int; numItems: int;
  normals: Webgl.WebGLBuffer
};

@private type engine = {
  context: Webgl.Context.private;
  canvas: { selector:dom; width: int; height: int };
  shaderProgram: my_custom_shaderProgram
  static_buffers: { repcoords: { x:static_buffer; y:static_buffer; z:static_buffer } };
  framePickBuffer: Webgl.WebGLFramebuffer
} ;

@client initPickBuffer(eng) =
  gl = eng.context;
  framePickBuffer = Webgl.createFramebuffer(gl);
  renderPickBuffer = Webgl.createRenderbuffer(gl);
  pickTexture = Webgl.createTexture(gl);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.some(pickTexture));
  tex = Webgl.Uint8Array.from_int_list([0, 0, 0]);
  do Webgl.texImage2D(gl, Webgl.TEXTURE_2D(gl), 0, Webgl.RGB(gl), eng.canvas.width, eng.canvas.height, 0, Webgl.RGB(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(tex));
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(framePickBuffer));
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.some(renderPickBuffer));
  do Webgl.renderbufferStorage(gl, Webgl.RENDERBUFFER(gl), Webgl.DEPTH_COMPONENT16(gl), eng.canvas.width, eng.canvas.height);
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.none);

  do Webgl.framebufferTexture2D(gl, Webgl.FRAMEBUFFER(gl), Webgl.COLOR_ATTACHMENT0(gl), Webgl.TEXTURE_2D(gl), pickTexture, 0);
  do Webgl.framebufferRenderbuffer(gl, Webgl.FRAMEBUFFER(gl), Webgl.DEPTH_ATTACHMENT(gl), Webgl.RENDERBUFFER(gl), renderPickBuffer);
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.none);
  framePickBuffer
;

initShaders(gl) =
  f(e, str) =
    shader = Webgl.createShader(gl, e);
    do Webgl.shaderSource(gl, shader, str);
    do Webgl.compileShader(gl, shader);
    shader;
  fragmentShader = f(Webgl.FRAGMENT_SHADER(gl), CustomShaders.shader_fs);
  vertexShader = f(Webgl.VERTEX_SHADER(gl), CustomShaders.shader_vs);
  // TODO getShaderParameter
  shaderProgram = Webgl.createProgram(gl);
  do Webgl.attachShader(gl, shaderProgram, vertexShader);
  do Webgl.attachShader(gl, shaderProgram, fragmentShader);
  do Webgl.linkProgram(gl, shaderProgram);
  // TODO : getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
  do Webgl.useProgram(gl, shaderProgram);
  shaderProgram =
    vertexPositionAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexPosition");
    vertexNormalAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexNormal");
    do Webgl.enableVertexAttribArray(gl, vertexPositionAttribute);
    do Webgl.enableVertexAttribArray(gl, vertexNormalAttribute);
    { program = shaderProgram;
      ~vertexPositionAttribute;
      ~vertexNormalAttribute;
      pMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uPMatrix");
      mvMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uMVMatrix");
      nMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uNMatrix");
      ambientColorUniform = Webgl.getUniformLocation(gl, shaderProgram, "uAmbientColor");
      lightingDirectionUniform = Webgl.getUniformLocation(gl, shaderProgram, "uLightingDirection");
      useLightingUniform = Webgl.getUniformLocation(gl, shaderProgram, "uUseLighting");
    };
  shaderProgram
;

initLineXBuffers(gl, orient) =
  (vertices, vertexNormals) = match orient with
    | {x} -> ([ 0.0, 0.0, 0.0, 5.0, 0.0, 0.0 ], [ 2.5, 0.0, 0.0,        2.5, -1.0, 0.0 ])
    | {y} -> ([ 0.0, 0.0, 0.0, 0.0, 5.0, 0.0 ], [ 0.0, 2.5, 0.0,        -1.0, 2.5, 0.0 ])
    | {z} -> ([ 0.0, 0.0, 0.0, 0.0, 0.0, 5.0 ], [ 0.0, 0.0, 2.5,        0.0, -1.0, 2.5 ])
    end ;
  vertexPositionBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexPositionBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertices)),
    Webgl.STATIC_DRAW(gl));
  vertexNormalBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexNormalBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertexNormals)),
    Webgl.STATIC_DRAW(gl));
  { positions=vertexPositionBuffer; itemSize=3; numItems=2; normals=vertexNormalBuffer }
;

setMatrixUniforms(gl, shaderProgram, pMatrix, mvMatrix) =
  a =
    b = mat4.to_list(pMatrix);
    c = Webgl.Float32Array.from_float_list(b);
    c;
  e =
    f = mat4.to_list(mvMatrix);
    g = Webgl.Float32Array.from_float_list(f);
    g;
  do Webgl.uniformMatrix4fv(gl, shaderProgram.pMatrixUniform, false, a);
  do Webgl.uniformMatrix4fv(gl, shaderProgram.mvMatrixUniform, false, e);
  normalMatrix = mat3.create();
  do mat4.toInverseMat3(mvMatrix, normalMatrix);
  do mat3.transpose(normalMatrix, normalMatrix);
  do Webgl.uniformMatrix3fv(gl, shaderProgram.nMatrixUniform, false, Webgl.Float32Array.from_float_list(mat3.to_list(normalMatrix)));
  void
;

setup_boxes(eng) =
  sep_largeur = 2;
  g(x, y, w, h) = { ~x; ~y; ~w; ~h } ;
  compute_left_right(x) = if ((mod(x, 2)) == 0) then
      a = (x / 2) - 1;
      (a, a)
    else
      b = (x / 2);
      (b - 1, b);
  (w_l, w_r) = compute_left_right(eng.canvas.width);
  (h_u, h_d) = compute_left_right(eng.canvas.height);
  { _YX=g(0, h_d+sep_largeur, w_l, h_u); _YZ=g(w_l+sep_largeur, h_d+sep_largeur, w_r, h_u);
    _ZX=g(0, 0, w_l, h_d); _3D=g(w_l+sep_largeur, 0, w_r, h_d) }
;

drawScene_for_a_viewport(eng, who, viewport, eye, up, scene, mode) =
  gl = eng.context; shaderProgram = eng.shaderProgram; repcoords = eng.static_buffers.repcoords;
  do Webgl.viewport(gl, viewport.x, viewport.y, viewport.w, viewport.h);
  pMatrix =
    tmp_pMatrix = mat4.create();
    match who with
    | {_YX} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      tmp_pMatrix
    | {_YZ} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      mat4.rotateY(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_ZX} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      mat4.rotateX(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_3D} ->
      do mat4.perspective(45., float_of_int(eng.canvas.width) / float_of_int(eng.canvas.height), 0.1, 100.0, tmp_pMatrix);
      c = mat4.create() ;
      do mat4.lookAt(vec3.from_public(eye), vec3.from_public((0.0, 0.0, 0.0)), vec3.from_public(up), c);
      do mat4.multiply(tmp_pMatrix, c, tmp_pMatrix);
      tmp_pMatrix
    end ;
  mvMatrix =
    tmp_mvMatrix = mat4.create();
    do mat4.identity(tmp_mvMatrix);
    Stack.push(Stack.create(), tmp_mvMatrix);
  do setMatrixUniforms(gl, shaderProgram, pMatrix, Stack.peek(mvMatrix));
  draw_rep(r, g, b, rep) =
    do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false
    do Webgl.uniform3f(gl, shaderProgram.ambientColorUniform, r, g, b);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.positions);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexPositionAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.normals);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexNormalAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.drawArrays(gl, Webgl.LINES(gl), 0, rep.numItems);
    void ;

  _ =
    match mode with
    | {normal} ->
      do draw_rep(1.0, 0.0, 0.0, repcoords.x);
      do draw_rep(0.0, 1.0, 0.0, repcoords.y);
      do draw_rep(0.0, 0.0, 1.0, repcoords.z);

      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 1); // 1 = true
      do Webgl.uniform3f(gl, shaderProgram.lightingDirectionUniform, 0.85, 0.8, 0.75);
      List.iter(((pos, object) -> display(eng, pMatrix, mvMatrix, pos.cube, object, false)), scene)
    | {pick} ->
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(eng.framePickBuffer));
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false;
      do List.iter(((pos, object) -> display(eng, pMatrix, mvMatrix, pos.cube, object, true)), scene);
      void
    end ;

  (pMatrix, mvMatrix)
;

drawScene_and_register(eng, get_scene : (->Modeler.scene), get_mode) =
  viewbox = setup_boxes(eng) ;
  rec aux(eng) =
    gl = eng.context;
    scene = List.map((p -> (p, Cube.create(gl, p.id))), get_scene());
    do match get_mode() with
    | {pick=pos; ~cont} ->
      //do Log.debug("Picking", "...");
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {pick});
      (pMatrix, s) = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {pick});
      //(pMatrix, s) = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
      x = (float_of_int(pos.x_px - viewbox._ZX.x) / float_of_int(viewbox._ZX.w)) * 2.0 - 1.0;
      y = (float_of_int(pos.y_px - viewbox._ZX.y) / float_of_int(viewbox._ZX.h)) * 2.0 - 1.0;
      mvMatrix = Stack.peek(s) ;
      do mat4.multiply(pMatrix, mvMatrix, mvMatrix);
      do mat4.inverse(mvMatrix, mvMatrix);
      v1 = vec4.from_public((x, y, 1.0, 1.0));
      v2 = vec4.from_public((9.9, 9.9, 9.9, 9.9));
      do mat4.multiplyVec4(mvMatrix, v1, v2);
      v22 = vec4.to_public(v2);
      //v22 = { v22 with f2=0.0 };
      v2 = (v22.f1 / v22.f4, v22.f2 / v22.f4, v22.f3 / v22.f4, v22.f4);
      data = Webgl.Uint8Array.from_int_list(List.init((_->123), 4));
      do Webgl.readPixels(gl, pos.x_px, pos.y_px, 1, 1, Webgl.RGBA(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(data));
      pickedColor = match Webgl.Uint8Array.to_int_list(data) with
        | [r, g, b, _] -> (r, g, b)
        | _ -> error("Picking failure")
        end ;
      do Log.debug("Picking", "Color is: { pickedColor }; v1={ vec4.str(v1) }, \t v2={ v2 }");
      //do jlog("Color is: { pickedColor }; v={ vec3.str(v) }");
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
      cont({ mousedown; x=v2.f1; z=v2.f3})
    | {normal} ->
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      void
    end ;
    do RequestAnimationFrame.request((_ -> aux(eng)), #{id_canvas_area});
    void
    ;
  aux(eng)
;

initGL(canvas_sel, width, height, get_scene, mouse_listener) : outcome =
  match WebGLUtils.setupWebGL_with_custom_failure(Dom.of_selection(canvas_sel)) with
  | { ok=context } ->
    mode = Mutable.make_client({normal});
    is_picking(m) = match m with | { pick=_; cont=_ } -> true | _ -> false end;
    _ =
      handler(e) =
        m_pos = // we transform the pos to be relative to the upper leftcorner of the canvas
          c_pos = Dom.get_offset(#{id_canvas_area});
          rel = e.mouse_position_on_page;
          { x_px=max(rel.x_px - c_pos.x_px, 0); y_px=max(rel.y_px - c_pos.y_px, 0) };
        // now with gl the origin will be at the lower left corner
        gl_pos = { x_px=min(max(m_pos.x_px,0), height-1); y_px=min(max(height - 1 - m_pos.y_px, 0), width-1) };
        cont(e) =
          do mode.set({normal});
          mouse_listener(e);
        do if not(is_picking(mode.get())) then mode.set({pick=gl_pos; ~cont});
        Log.debug("P", "[(,)-({m_pos.x_px},{m_pos.y_px})] {gl_pos.x_px}, {gl_pos.y_px}");
      Dom.bind(canvas_sel, { mousedown }, handler);
    gl = context;
    eng : engine =
      start = @openrecord({ context=gl; canvas={ selector=canvas_sel; ~width; ~height } });
      start = { start with shaderProgram=initShaders(gl) };
      start = { start with framePickBuffer=initPickBuffer(start) } ;
      { start with static_buffers.repcoords=
        { x=initLineXBuffers(gl, {x}); y=initLineXBuffers(gl, {y}); z=initLineXBuffers(gl, {z}) } };
    //Clear screen and make everything light gray
    do Webgl.clearColor(gl, 0.9, 0.9, 0.9, 1.0);
    //we should do depth testing so that things drawn behind other
    //things should be hidden by the things in front of them).
    do Webgl.clearDepth(gl, 1.0);
    do Webgl.enable(gl, Webgl.DEPTH_TEST(gl));
    do Webgl.depthFunc(gl, Webgl.LEQUAL(gl));
    do drawScene_and_register(eng, get_scene, mode.get);
    { success }
  | { ~ko } -> { failure=ko }
  end ;

@private type my_custom_shaderProgram = {
  program: Webgl.WebGLProgram;
  vertexPositionAttribute: Webgl.GLint;
  vertexNormalAttribute: Webgl.GLint;
  pMatrixUniform: Webgl.WebGLUniformLocation;
  mvMatrixUniform: Webgl.WebGLUniformLocation;
  nMatrixUniform: Webgl.WebGLUniformLocation;
  ambientColorUniform: Webgl.WebGLUniformLocation;
  lightingDirectionUniform: Webgl.WebGLUniformLocation;
  useLightingUniform: Webgl.WebGLUniformLocation
};

@private type static_buffer = {
  positions: Webgl.WebGLBuffer;
  itemSize: int; numItems: int;
  normals: Webgl.WebGLBuffer
};

@private type engine = {
  context: Webgl.Context.private;
  canvas: { selector:dom; width: int; height: int };
  shaderProgram: my_custom_shaderProgram
  static_buffers: { repcoords: { x:static_buffer; y:static_buffer; z:static_buffer } };
  framePickBuffer: Webgl.WebGLFramebuffer
} ;

@client initPickBuffer(eng) =
  gl = eng.context;
  framePickBuffer = Webgl.createFramebuffer(gl);
  renderPickBuffer = Webgl.createRenderbuffer(gl);
  pickTexture = Webgl.createTexture(gl);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.some(pickTexture));
  tex = Webgl.Uint8Array.from_int_list([0, 0, 0]);
  do Webgl.texImage2D(gl, Webgl.TEXTURE_2D(gl), 0, Webgl.RGB(gl), eng.canvas.width, eng.canvas.height, 0, Webgl.RGB(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(tex));
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(framePickBuffer));
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.some(renderPickBuffer));
  do Webgl.renderbufferStorage(gl, Webgl.RENDERBUFFER(gl), Webgl.DEPTH_COMPONENT16(gl), eng.canvas.width, eng.canvas.height);
  do Webgl.bindRenderbuffer(gl, Webgl.RENDERBUFFER(gl), Option.none);

  do Webgl.framebufferTexture2D(gl, Webgl.FRAMEBUFFER(gl), Webgl.COLOR_ATTACHMENT0(gl), Webgl.TEXTURE_2D(gl), pickTexture, 0);
  do Webgl.framebufferRenderbuffer(gl, Webgl.FRAMEBUFFER(gl), Webgl.DEPTH_ATTACHMENT(gl), Webgl.RENDERBUFFER(gl), renderPickBuffer);
  do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
  do Webgl.bindTexture(gl, Webgl.TEXTURE_2D(gl), Option.none);
  framePickBuffer
;

initShaders(gl) =
  f(e, str) =
    shader = Webgl.createShader(gl, e);
    do Webgl.shaderSource(gl, shader, str);
    do Webgl.compileShader(gl, shader);
    shader;
  fragmentShader = f(Webgl.FRAGMENT_SHADER(gl), CustomShaders.shader_fs);
  vertexShader = f(Webgl.VERTEX_SHADER(gl), CustomShaders.shader_vs);
  // TODO getShaderParameter
  shaderProgram = Webgl.createProgram(gl);
  do Webgl.attachShader(gl, shaderProgram, vertexShader);
  do Webgl.attachShader(gl, shaderProgram, fragmentShader);
  do Webgl.linkProgram(gl, shaderProgram);
  // TODO : getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
  do Webgl.useProgram(gl, shaderProgram);
  shaderProgram =
    vertexPositionAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexPosition");
    vertexNormalAttribute = Webgl.getAttribLocation(gl, shaderProgram, "aVertexNormal");
    do Webgl.enableVertexAttribArray(gl, vertexPositionAttribute);
    do Webgl.enableVertexAttribArray(gl, vertexNormalAttribute);
    { program = shaderProgram;
      ~vertexPositionAttribute;
      ~vertexNormalAttribute;
      pMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uPMatrix");
      mvMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uMVMatrix");
      nMatrixUniform = Webgl.getUniformLocation(gl, shaderProgram, "uNMatrix");
      ambientColorUniform = Webgl.getUniformLocation(gl, shaderProgram, "uAmbientColor");
      lightingDirectionUniform = Webgl.getUniformLocation(gl, shaderProgram, "uLightingDirection");
      useLightingUniform = Webgl.getUniformLocation(gl, shaderProgram, "uUseLighting");
    };
  shaderProgram
;

initLineXBuffers(gl, orient) =
  (vertices, vertexNormals) = match orient with
    | {x} -> ([ 0.0, 0.0, 0.0, 5.0, 0.0, 0.0 ], [ 2.5, 0.0, 0.0,        2.5, -1.0, 0.0 ])
    | {y} -> ([ 0.0, 0.0, 0.0, 0.0, 5.0, 0.0 ], [ 0.0, 2.5, 0.0,        -1.0, 2.5, 0.0 ])
    | {z} -> ([ 0.0, 0.0, 0.0, 0.0, 0.0, 5.0 ], [ 0.0, 0.0, 2.5,        0.0, -1.0, 2.5 ])
    end ;
  vertexPositionBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexPositionBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertices)),
    Webgl.STATIC_DRAW(gl));
  vertexNormalBuffer = Webgl.createBuffer(gl);
  do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), vertexNormalBuffer);
  do Webgl.bufferData(gl, Webgl.ARRAY_BUFFER(gl),
    Webgl.Float32Array.to_ArrayBuffer(Webgl.Float32Array.from_float_list(vertexNormals)),
    Webgl.STATIC_DRAW(gl));
  { positions=vertexPositionBuffer; itemSize=3; numItems=2; normals=vertexNormalBuffer }
;

setMatrixUniforms(gl, shaderProgram, pMatrix, mvMatrix) =
  a =
    b = mat4.to_list(pMatrix);
    c = Webgl.Float32Array.from_float_list(b);
    c;
  e =
    f = mat4.to_list(mvMatrix);
    g = Webgl.Float32Array.from_float_list(f);
    g;
  do Webgl.uniformMatrix4fv(gl, shaderProgram.pMatrixUniform, false, a);
  do Webgl.uniformMatrix4fv(gl, shaderProgram.mvMatrixUniform, false, e);
  normalMatrix = mat3.create();
  do mat4.toInverseMat3(mvMatrix, normalMatrix);
  do mat3.transpose(normalMatrix, normalMatrix);
  do Webgl.uniformMatrix3fv(gl, shaderProgram.nMatrixUniform, false, Webgl.Float32Array.from_float_list(mat3.to_list(normalMatrix)));
  void
;

setup_boxes(eng) =
  sep_largeur = 2;
  g(x, y, w, h) = { ~x; ~y; ~w; ~h } ;
  compute_left_right(x) = if ((mod(x, 2)) == 0) then
      a = (x / 2) - 1;
      (a, a)
    else
      b = (x / 2);
      (b - 1, b);
  (w_l, w_r) = compute_left_right(eng.canvas.width);
  (h_u, h_d) = compute_left_right(eng.canvas.height);
  { _YX=g(0, h_d+sep_largeur, w_l, h_u); _YZ=g(w_l+sep_largeur, h_d+sep_largeur, w_r, h_u);
    _ZX=g(0, 0, w_l, h_d); _3D=g(w_l+sep_largeur, 0, w_r, h_d) }
;

@client (pc, register_color) =
  bank = Mutable.make_client(IntMap.empty : intmap((float, float, float)));
  c() =
    r() = Random.float(1.0);
    (r(), r(), r()) ;
  //List.fold((e, acc -> IntMap.add(e, c(), acc)), List.init(identity, 10), IntMap.empty)
  (i -> IntMap.get(i, bank.get()), (i -> bank.set(IntMap.add(i, IntMap.get(i, bank.get()) ? c(), bank.get()))))
;

drawScene_for_a_viewport(eng, who, viewport, eye, up, scene, mode) =
  gl = eng.context; shaderProgram = eng.shaderProgram; repcoords = eng.static_buffers.repcoords;
  do Webgl.viewport(gl, viewport.x, viewport.y, viewport.w, viewport.h);
  pMatrix =
    tmp_pMatrix = mat4.create();
    match who with
    | {_YX} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      tmp_pMatrix
    | {_YZ} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      mat4.rotateY(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_ZX} ->
      do mat4.ortho(-7., 7., -7., 7., -10., 10., tmp_pMatrix);
      mat4.rotateX(tmp_pMatrix, (90. * Math.PI / 180.), tmp_pMatrix)
    | {_3D} ->
      do mat4.perspective(45., float_of_int(eng.canvas.width) / float_of_int(eng.canvas.height), 0.1, 100.0, tmp_pMatrix);
      c = mat4.create() ;
      do mat4.lookAt(vec3.from_public(eye), vec3.from_public((0.0, 0.0, 0.0)), vec3.from_public(up), c);
      do mat4.multiply(tmp_pMatrix, c, tmp_pMatrix);
      tmp_pMatrix
    end ;
  mvMatrix =
    tmp_mvMatrix = mat4.create();
    do mat4.identity(tmp_mvMatrix);
    Stack.push(Stack.create(), tmp_mvMatrix);
  do setMatrixUniforms(gl, shaderProgram, pMatrix, Stack.peek(mvMatrix));
  draw_rep(r, g, b, rep) =
    do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false
    do Webgl.uniform3f(gl, shaderProgram.ambientColorUniform, r, g, b);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.positions);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexPositionAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.bindBuffer(gl, Webgl.ARRAY_BUFFER(gl), rep.normals);
    do Webgl.vertexAttribPointer(gl, shaderProgram.vertexNormalAttribute, rep.itemSize, Webgl.FLOAT(gl), false, 0, 0);
    do Webgl.drawArrays(gl, Webgl.LINES(gl), 0, rep.numItems);
    void ;

  _ =
    match mode with
    | {normal} ->
      do draw_rep(1.0, 0.0, 0.0, repcoords.x);
      do draw_rep(0.0, 1.0, 0.0, repcoords.y);
      do draw_rep(0.0, 0.0, 1.0, repcoords.z);

      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 1); // 1 = true
      do Webgl.uniform3f(gl, shaderProgram.lightingDirectionUniform, 0.85, 0.8, 0.75);
      List.iter(((pos, object) -> display(eng, pMatrix, mvMatrix, pos.cube, object, false)), scene)
    | {pick} ->
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.some(eng.framePickBuffer));
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      do Webgl.uniform1i(gl, shaderProgram.useLightingUniform, 0); // 0 = false;
      c(i) = pc(i) ? (0.1, 0.2, 0.3);
      do List.iter(((pos, object) -> display(eng, pMatrix, mvMatrix, pos.cube, object, true)), scene);
      void
    end ;

  (pMatrix, mvMatrix)
;

drawScene_and_register(eng, get_scene : (->Modeler.scene), get_mode) =
  viewbox = setup_boxes(eng) ;
  rec aux(eng) =
    gl = eng.context;
    scene = List.map((p -> (p, do register_color(p.id); Cube.create(gl, p.id))), get_scene());
    do match get_mode() with
    | {pick=pos; ~cont} ->
      //do Log.debug("Picking", "...");
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {pick});
      (pMatrix, s) = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {pick});
      //(pMatrix, s) = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {pick});
      x = (float_of_int(pos.x_px - viewbox._ZX.x) / float_of_int(viewbox._ZX.w)) * 2.0 - 1.0;
      y = (float_of_int(pos.y_px - viewbox._ZX.y) / float_of_int(viewbox._ZX.h)) * 2.0 - 1.0;
      mvMatrix = Stack.peek(s) ;
      do mat4.multiply(pMatrix, mvMatrix, mvMatrix);
      do mat4.inverse(mvMatrix, mvMatrix);
      v1 = vec4.from_public((x, y, 1.0, 1.0));
      v2 = vec4.from_public((9.9, 9.9, 9.9, 9.9));
      do mat4.multiplyVec4(mvMatrix, v1, v2);
      v22 = vec4.to_public(v2);
      //v22 = { v22 with f2=0.0 };
      v2 = (v22.f1 / v22.f4, v22.f2 / v22.f4, v22.f3 / v22.f4, v22.f4);
      data = Webgl.Uint8Array.from_int_list(List.init((_->123), 4));
      do Webgl.readPixels(gl, pos.x_px, pos.y_px, 1, 1, Webgl.RGBA(gl), Webgl.UNSIGNED_BYTE(gl), Webgl.Uint8Array.to_ArrayBuffer(data));
      pickedColor = match Webgl.Uint8Array.to_int_list(data) with
        | [r, g, b, _] -> (r, g, b)
        | _ -> error("Picking failure")
        end ;
      do Log.debug("Picking", "Color is: { pickedColor }; v1={ vec4.str(v1) }, \t v2={ v2 }");
      //do jlog("Color is: { pickedColor }; v={ vec3.str(v) }");
      do Webgl.bindFramebuffer(gl, Webgl.FRAMEBUFFER(gl), Option.none);
      cont({ mousedown; x=v2.f1; z=v2.f3})
    | {normal} ->
      do Webgl.clear(gl, Webgl.GLbitfield_OR(Webgl.COLOR_BUFFER_BIT(gl), Webgl.DEPTH_BUFFER_BIT(gl)));
      _ = drawScene_for_a_viewport(eng, {_YX}, viewbox._YX, (0.0, 0.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_YZ}, viewbox._YZ, (-15.0, 0.0, 0.0), (0.0, 1.0, 0.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_ZX}, viewbox._ZX, (0.0, -15.0, 0.0), (0.0, 0.0, 1.0), scene, {normal});
      _ = drawScene_for_a_viewport(eng, {_3D}, viewbox._3D, (10.0, 5.0, 15.0), (0.0, 1.0, 0.0), scene, {normal});
      void
    end ;
    do RequestAnimationFrame.request((_ -> aux(eng)), #{id_canvas_area});
    void
    ;
  aux(eng)
;

initGL(canvas_sel, width, height, get_scene, mouse_listener) : outcome =
  match WebGLUtils.setupWebGL_with_custom_failure(Dom.of_selection(canvas_sel)) with
  | { ok=context } ->
    mode = Mutable.make_client({normal});
    is_picking(m) = match m with | { pick=_; cont=_ } -> true | _ -> false end;
    _ =
      handler(e) =
        m_pos = // we transform the pos to be relative to the upper leftcorner of the canvas
          c_pos = Dom.get_offset(#{id_canvas_area});
          rel = e.mouse_position_on_page;
          { x_px=max(rel.x_px - c_pos.x_px, 0); y_px=max(rel.y_px - c_pos.y_px, 0) };
        // now with gl the origin will be at the lower left corner
        gl_pos = { x_px=min(max(m_pos.x_px,0), height-1); y_px=min(max(height - 1 - m_pos.y_px, 0), width-1) };
        cont(e) =
          do mode.set({normal});
          mouse_listener(e);
        do if not(is_picking(mode.get())) then mode.set({pick=gl_pos; ~cont});
        Log.debug("P", "[(,)-({m_pos.x_px},{m_pos.y_px})] {gl_pos.x_px}, {gl_pos.y_px}");
      Dom.bind(canvas_sel, { mousedown }, handler);
    gl = context;
    eng : engine =
      start = @openrecord({ context=gl; canvas={ selector=canvas_sel; ~width; ~height } });
      start = { start with shaderProgram=initShaders(gl) };
      start = { start with framePickBuffer=initPickBuffer(start) } ;
      { start with static_buffers.repcoords=
        { x=initLineXBuffers(gl, {x}); y=initLineXBuffers(gl, {y}); z=initLineXBuffers(gl, {z}) } };
    //Clear screen and make everything light gray
    do Webgl.clearColor(gl, 0.9, 0.9, 0.9, 1.0);
    //we should do depth testing so that things drawn behind other
    //things should be hidden by the things in front of them).
    do Webgl.clearDepth(gl, 1.0);
    do Webgl.enable(gl, Webgl.DEPTH_TEST(gl));
    do Webgl.depthFunc(gl, Webgl.LEQUAL(gl));
    do drawScene_and_register(eng, get_scene, mode.get);
    { success }
  | { ~ko } -> { failure=ko }
  end ;