text: /*
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2
   * of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   *
   * Copyright 2016, Blender Foundation.
   */
  
  /** \file
   * \ingroup draw
   */
  
  #include "DRW_engine.h"
  #include "DRW_render.h"
  
  #include "DNA_curve_types.h"
  
  #include "BIF_glutil.h"
  
  #include "BKE_font.h"
  
  /* If builtin shaders are needed */
  #include "GPU_shader.h"
  
  #include "draw_common.h"
  #include "draw_mode_engines.h"
  
  /* *********** LISTS *********** */
  /* All lists are per viewport specific datas.
   * They are all free when viewport changes engines
   * or is free itself. Use EDIT_TEXT_engine_init() to
   * initialize most of them and EDIT_TEXT_cache_init()
   * for EDIT_TEXT_PassList */
  
  typedef struct EDIT_TEXT_PassList {
    /* Declare all passes here and init them in
     * EDIT_TEXT_cache_init().
     * Only contains (DRWPass *) */
    struct DRWPass *wire_pass;
    struct DRWPass *overlay_select_pass;
    struct DRWPass *overlay_cursor_pass;
    struct DRWPass *text_box_pass;
  } EDIT_TEXT_PassList;
  
  typedef struct EDIT_TEXT_FramebufferList {
    /* Contains all framebuffer objects needed by this engine.
     * Only contains (GPUFrameBuffer *) */
    struct GPUFrameBuffer *fb;
  } EDIT_TEXT_FramebufferList;
  
  typedef struct EDIT_TEXT_TextureList {
    /* Contains all framebuffer textures / utility textures
     * needed by this engine. Only viewport specific textures
     * (not per object). Only contains (GPUTexture *) */
    struct GPUTexture *texture;
  } EDIT_TEXT_TextureList;
  
  typedef struct EDIT_TEXT_StorageList {
    /* Contains any other memory block that the engine needs.
     * Only directly MEM_(m/c)allocN'ed blocks because they are
     * free with MEM_freeN() when viewport is freed.
     * (not per object) */
    struct CustomStruct *block;
    struct EDIT_TEXT_PrivateData *g_data;
  } EDIT_TEXT_StorageList;
  
  typedef struct EDIT_TEXT_Data {
    /* Struct returned by DRW_viewport_engine_data_ensure.
     * If you don't use one of these, just make it a (void *) */
    // void *fbl;
    void *engine_type; /* Required */
    EDIT_TEXT_FramebufferList *fbl;
    EDIT_TEXT_TextureList *txl;
    EDIT_TEXT_PassList *psl;
    EDIT_TEXT_StorageList *stl;
  } EDIT_TEXT_Data;
  
  /* *********** STATIC *********** */
  
  static struct {
    /* Custom shaders :
     * Add sources to source/blender/draw/modes/shaders
     * init in EDIT_TEXT_engine_init();
     * free in EDIT_TEXT_engine_free(); */
    GPUShader *wire_sh;
    GPUShader *overlay_select_sh;
    GPUShader *overlay_cursor_sh;
  } e_data = {NULL}; /* Engine data */
  
  typedef struct EDIT_TEXT_PrivateData {
    /* resulting curve as 'wire' for fast editmode drawing */
    DRWShadingGroup *wire_shgrp;
    DRWShadingGroup *overlay_select_shgrp;
    DRWShadingGroup *overlay_cursor_shgrp;
    DRWCallBuffer *box_shgrp;
    DRWCallBuffer *box_active_shgrp;
  } EDIT_TEXT_PrivateData; /* Transient data */
  
  /* *********** FUNCTIONS *********** */
  
  /* Init Textures, Framebuffers, Storage and Shaders.
   * It is called for every frames.
   * (Optional) */
  static void EDIT_TEXT_engine_init(void *vedata)
  {
    EDIT_TEXT_TextureList *txl = ((EDIT_TEXT_Data *)vedata)->txl;
    EDIT_TEXT_FramebufferList *fbl = ((EDIT_TEXT_Data *)vedata)->fbl;
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
  
    UNUSED_VARS(txl, fbl, stl);
  
    /* Init Framebuffers like this: order is attachment order (for color texs) */
    /*
     * DRWFboTexture tex[2] = {{&txl->depth, GPU_DEPTH_COMPONENT24, 0},
     *                         {&txl->color, GPU_RGBA8, DRW_TEX_FILTER}};
     */
  
    /* DRW_framebuffer_init takes care of checking if
     * the framebuffer is valid and has the right size*/
    /*
     * float *viewport_size = DRW_viewport_size_get();
     * DRW_framebuffer_init(&fbl->occlude_wire_fb,
     *                     (int)viewport_size[0], (int)viewport_size[1],
     *                     tex, 2);
     */
  
    if (!e_data.wire_sh) {
      e_data.wire_sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
    }
  
    if (!e_data.overlay_select_sh) {
      e_data.overlay_select_sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
    }
  
    if (!e_data.overlay_cursor_sh) {
      e_data.overlay_cursor_sh = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
    }
  }
  
  /* Here init all passes and shading groups
   * Assume that all Passes are NULL */
  static void EDIT_TEXT_cache_init(void *vedata)
  {
    const DRWContextState *draw_ctx = DRW_context_state_get();
    EDIT_TEXT_PassList *psl = ((EDIT_TEXT_Data *)vedata)->psl;
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
  
    if (!stl->g_data) {
      /* Alloc transient pointers */
      stl->g_data = MEM_mallocN(sizeof(*stl->g_data), __func__);
    }
  
    {
      /* Text outline (fast drawing!) */
      psl->wire_pass = DRW_pass_create(
          "Font Wire", DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL);
      stl->g_data->wire_shgrp = DRW_shgroup_create(e_data.wire_sh, psl->wire_pass);
  
      psl->overlay_select_pass = DRW_pass_create("Font Select",
                                                 DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH);
      stl->g_data->overlay_select_shgrp = DRW_shgroup_create(e_data.overlay_select_sh,
                                                             psl->overlay_select_pass);
  
      psl->overlay_cursor_pass = DRW_pass_create("Font Cursor",
                                                 DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH);
      stl->g_data->overlay_cursor_shgrp = DRW_shgroup_create(e_data.overlay_cursor_sh,
                                                             psl->overlay_cursor_pass);
  
      psl->text_box_pass = DRW_pass_create("Font Text Boxes",
                                           DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH);
      stl->g_data->box_shgrp = buffer_dynlines_dashed_uniform_color(
          psl->text_box_pass, G_draw.block.colorWire, draw_ctx->sh_cfg);
      stl->g_data->box_active_shgrp = buffer_dynlines_dashed_uniform_color(
          psl->text_box_pass, G_draw.block.colorActive, draw_ctx->sh_cfg);
    }
  }
  
  /* Use 2D quad corners to create a matrix that set
   * a [-1..1] quad at the right position. */
  static void v2_quad_corners_to_mat4(float corners[4][2], float r_mat[4][4])
  {
    unit_m4(r_mat);
    sub_v2_v2v2(r_mat[0], corners[1], corners[0]);
    sub_v2_v2v2(r_mat[1], corners[3], corners[0]);
    mul_v2_fl(r_mat[0], 0.5f);
    mul_v2_fl(r_mat[1], 0.5f);
    copy_v2_v2(r_mat[3], corners[0]);
    add_v2_v2(r_mat[3], r_mat[0]);
    add_v2_v2(r_mat[3], r_mat[1]);
  }
  
  static void edit_text_cache_populate_select(void *vedata, Object *ob)
  {
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
    const Curve *cu = ob->data;
    EditFont *ef = cu->editfont;
    float final_mat[4][4], box[4][2];
    struct GPUBatch *geom = DRW_cache_quad_get();
  
    for (int i = 0; i < ef->selboxes_len; i++) {
      EditFontSelBox *sb = &ef->selboxes[i];
  
      float selboxw;
      if (i + 1 != ef->selboxes_len) {
        if (ef->selboxes[i + 1].y == sb->y) {
          selboxw = ef->selboxes[i + 1].x - sb->x;
        }
        else {
          selboxw = sb->w;
        }
      }
      else {
        selboxw = sb->w;
      }
      /* NOTE: v2_quad_corners_to_mat4 don't need the 3rd corner. */
      if (sb->rot == 0.0f) {
        copy_v2_fl2(box[0], sb->x, sb->y);
        copy_v2_fl2(box[1], sb->x + selboxw, sb->y);
        copy_v2_fl2(box[3], sb->x, sb->y + sb->h);
      }
      else {
        float mat[2][2];
        angle_to_mat2(mat, sb->rot);
        copy_v2_fl2(box[0], sb->x, sb->y);
        mul_v2_v2fl(box[1], mat[0], selboxw);
        add_v2_v2(box[1], &sb->x);
        mul_v2_v2fl(box[3], mat[1], sb->h);
        add_v2_v2(box[3], &sb->x);
      }
      v2_quad_corners_to_mat4(box, final_mat);
      mul_m4_m4m4(final_mat, ob->obmat, final_mat);
  
      DRW_shgroup_call_obmat(stl->g_data->overlay_select_shgrp, geom, final_mat);
    }
  }
  
  static void edit_text_cache_populate_cursor(void *vedata, Object *ob)
  {
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
    const Curve *cu = ob->data;
    EditFont *edit_font = cu->editfont;
    float(*cursor)[2] = edit_font->textcurs;
    float mat[4][4];
  
    v2_quad_corners_to_mat4(cursor, mat);
    mul_m4_m4m4(mat, ob->obmat, mat);
  
    struct GPUBatch *geom = DRW_cache_quad_get();
    DRW_shgroup_call_obmat(stl->g_data->overlay_cursor_shgrp, geom, mat);
  }
  
  static void edit_text_cache_populate_boxes(void *vedata, Object *ob)
  {
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
    const Curve *cu = ob->data;
  
    DRWCallBuffer *callbufs[] = {
        stl->g_data->box_active_shgrp,
        stl->g_data->box_shgrp,
    };
  
    float vec[3], vec1[3], vec2[3];
    for (int i = 0; i < cu->totbox; i++) {
      TextBox *tb = &cu->tb[i];
  
      if ((tb->w == 0.0f) && (tb->h == 0.0f)) {
        continue;
      }
  
      const bool is_active = i == (cu->actbox - 1);
      DRWCallBuffer *callbuf = callbufs[is_active ? 0 : 1];
  
      vec[0] = cu->xof + tb->x;
      vec[1] = cu->yof + tb->y + cu->fsize_realtime;
      vec[2] = 0.001;
  
      mul_v3_m4v3(vec1, ob->obmat, vec);
      vec[0] += tb->w;
      mul_v3_m4v3(vec2, ob->obmat, vec);
  
      DRW_buffer_add_entry(callbuf, vec1);
      DRW_buffer_add_entry(callbuf, vec2);
  
      vec[1] -= tb->h;
      copy_v3_v3(vec1, vec2);
      mul_v3_m4v3(vec2, ob->obmat, vec);
  
      DRW_buffer_add_entry(callbuf, vec1);
      DRW_buffer_add_entry(callbuf, vec2);
  
      vec[0] -= tb->w;
      copy_v3_v3(vec1, vec2);
      mul_v3_m4v3(vec2, ob->obmat, vec);
  
      DRW_buffer_add_entry(callbuf, vec1);
      DRW_buffer_add_entry(callbuf, vec2);
  
      vec[1] += tb->h;
      copy_v3_v3(vec1, vec2);
      mul_v3_m4v3(vec2, ob->obmat, vec);
  
      DRW_buffer_add_entry(callbuf, vec1);
      DRW_buffer_add_entry(callbuf, vec2);
    }
  }
  
  /* Add geometry to shadingGroups. Execute for each objects */
  static void EDIT_TEXT_cache_populate(void *vedata, Object *ob)
  {
    EDIT_TEXT_PassList *psl = ((EDIT_TEXT_Data *)vedata)->psl;
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
    const DRWContextState *draw_ctx = DRW_context_state_get();
  
    UNUSED_VARS(psl, stl);
  
    if (ob->type == OB_FONT) {
      if (ob == draw_ctx->object_edit) {
        const Curve *cu = ob->data;
        /* Get geometry cache */
        struct GPUBatch *geom;
  
        bool has_surface = (cu->flag & (CU_FRONT | CU_BACK)) || cu->ext1 != 0.0f || cu->ext2 != 0.0f;
        if ((cu->flag & CU_FAST) || !has_surface) {
          geom = DRW_cache_text_edge_wire_get(ob);
          if (geom) {
            DRW_shgroup_call(stl->g_data->wire_shgrp, geom, ob);
          }
        }
        else {
          /* object mode draws */
        }
  
        edit_text_cache_populate_select(vedata, ob);
        edit_text_cache_populate_cursor(vedata, ob);
        edit_text_cache_populate_boxes(vedata, ob);
      }
    }
  }
  
  /* Optional: Post-cache_populate callback */
  static void EDIT_TEXT_cache_finish(void *vedata)
  {
    EDIT_TEXT_PassList *psl = ((EDIT_TEXT_Data *)vedata)->psl;
    EDIT_TEXT_StorageList *stl = ((EDIT_TEXT_Data *)vedata)->stl;
  
    /* Do something here! dependent on the objects gathered */
    UNUSED_VARS(psl, stl);
  }
  
  /* Draw time ! Control rendering pipeline from here */
  static void EDIT_TEXT_draw_scene(void *vedata)
  {
    EDIT_TEXT_PassList *psl = ((EDIT_TEXT_Data *)vedata)->psl;
    EDIT_TEXT_FramebufferList *fbl = ((EDIT_TEXT_Data *)vedata)->fbl;
  
    /* Default framebuffer and texture */
    DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
    DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
  
    UNUSED_VARS(fbl, dfbl, dtxl);
  
    /* Show / hide entire passes, swap framebuffers ... whatever you fancy */
    /*
     * DRW_framebuffer_texture_detach(dtxl->depth);
     * DRW_framebuffer_bind(fbl->custom_fb);
     * DRW_draw_pass(psl->pass);
     * DRW_framebuffer_texture_attach(dfbl->default_fb, dtxl->depth, 0, 0);
     * DRW_framebuffer_bind(dfbl->default_fb);
     */
  
    DRW_draw_pass(psl->wire_pass);
  
    if (!DRW_pass_is_empty(psl->text_box_pass)) {
      DRW_draw_pass(psl->text_box_pass);
    }
  
    set_inverted_drawing(1);
    DRW_draw_pass(psl->overlay_select_pass);
    DRW_draw_pass(psl->overlay_cursor_pass);
    set_inverted_drawing(0);
  
    /* If you changed framebuffer, double check you rebind
     * the default one with its textures attached before finishing */
  }
  
  /* Cleanup when destroying the engine.
   * This is not per viewport ! only when quitting blender.
   * Mostly used for freeing shaders */
  static void EDIT_TEXT_engine_free(void)
  {
    // DRW_SHADER_FREE_SAFE(custom_shader);
  }
  
  static const DrawEngineDataSize EDIT_TEXT_data_size = DRW_VIEWPORT_DATA_SIZE(EDIT_TEXT_Data);
  
  DrawEngineType draw_engine_edit_text_type = {
      NULL,
      NULL,
      N_("EditTextMode"),
      &EDIT_TEXT_data_size,
      &EDIT_TEXT_engine_init,
      &EDIT_TEXT_engine_free,
      &EDIT_TEXT_cache_init,
      &EDIT_TEXT_cache_populate,
      &EDIT_TEXT_cache_finish,
      NULL, /* draw_background but not needed by mode engines */
      &EDIT_TEXT_draw_scene,
      NULL,
      NULL,
  };
  