text: /**************************************************************************
   *
   * Copyright 2007-2018 VMware, Inc.
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sub license, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial portions
   * of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
   * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
   * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
   * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
   * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   **************************************************************************/
  
  /**
   * AA line stage:  AA lines are converted triangles (with extra generic)
   *
   * Authors:  Brian Paul
   */
  
  
  #include "pipe/p_context.h"
  #include "pipe/p_defines.h"
  #include "pipe/p_shader_tokens.h"
  #include "util/u_inlines.h"
  
  #include "util/u_format.h"
  #include "util/u_math.h"
  #include "util/u_memory.h"
  
  #include "tgsi/tgsi_transform.h"
  #include "tgsi/tgsi_dump.h"
  
  #include "draw_context.h"
  #include "draw_private.h"
  #include "draw_pipe.h"
  
  
  /** Approx number of new tokens for instructions in aa_transform_inst() */
  #define NUM_NEW_TOKENS 53
  
  
  /**
   * Subclass of pipe_shader_state to carry extra fragment shader info.
   */
  struct aaline_fragment_shader
  {
     struct pipe_shader_state state;
     void *driver_fs;
     void *aaline_fs;
     int generic_attrib;  /**< generic used for distance */
  };
  
  
  /**
   * Subclass of draw_stage
   */
  struct aaline_stage
  {
     struct draw_stage stage;
  
     float half_line_width;
  
     /** For AA lines, this is the vertex attrib slot for new generic */
     uint coord_slot;
     /** position, not necessarily output zero */
     uint pos_slot;
  
  
     /*
      * Currently bound state
      */
     struct aaline_fragment_shader *fs;
  
     /*
      * Driver interface/override functions
      */
     void * (*driver_create_fs_state)(struct pipe_context *,
                                      const struct pipe_shader_state *);
     void (*driver_bind_fs_state)(struct pipe_context *, void *);
     void (*driver_delete_fs_state)(struct pipe_context *, void *);
  };
  
  
  
  /**
   * Subclass of tgsi_transform_context, used for transforming the
   * user's fragment shader to add the special AA instructions.
   */
  struct aa_transform_context {
     struct tgsi_transform_context base;
     uint64_t tempsUsed;  /**< bitmask */
     int colorOutput; /**< which output is the primary color */
     int maxInput, maxGeneric;  /**< max input index found */
     int colorTemp, aaTemp;  /**< temp registers */
  };
  
  /**
   * TGSI declaration transform callback.
   * Look for a free input attrib, and two free temp regs.
   */
  static void
  aa_transform_decl(struct tgsi_transform_context *ctx,
                    struct tgsi_full_declaration *decl)
  {
     struct aa_transform_context *aactx = (struct aa_transform_context *)ctx;
  
     if (decl->Declaration.File == TGSI_FILE_OUTPUT &&
         decl->Semantic.Name == TGSI_SEMANTIC_COLOR &&
         decl->Semantic.Index == 0) {
        aactx->colorOutput = decl->Range.First;
     }
     else if (decl->Declaration.File == TGSI_FILE_INPUT) {
        if ((int) decl->Range.Last > aactx->maxInput)
           aactx->maxInput = decl->Range.Last;
        if (decl->Semantic.Name == TGSI_SEMANTIC_GENERIC &&
             (int) decl->Semantic.Index > aactx->maxGeneric) {
           aactx->maxGeneric = decl->Semantic.Index;
        }
     }
     else if (decl->Declaration.File == TGSI_FILE_TEMPORARY) {
        uint i;
        for (i = decl->Range.First;
             i <= decl->Range.Last; i++) {
           /*
            * XXX this bitfield doesn't really cut it...
            */
           aactx->tempsUsed |= UINT64_C(1) << i;
        }
     }
  
     ctx->emit_declaration(ctx, decl);
  }
  
  
  /**
   * Find the lowest zero bit, or -1 if bitfield is all ones.
   */
  static int
  free_bit(uint64_t bitfield)
  {
     return ffsll(~bitfield) - 1;
  }
  
  
  /**
   * TGSI transform prolog callback.
   */
  static void
  aa_transform_prolog(struct tgsi_transform_context *ctx)
  {
     struct aa_transform_context *aactx = (struct aa_transform_context *) ctx;
     uint64_t usedTemps = aactx->tempsUsed;
  
     /* find two free temp regs */
     aactx->colorTemp = free_bit(usedTemps);
     usedTemps |= UINT64_C(1) << aactx->colorTemp;
     aactx->aaTemp = free_bit(usedTemps);
     assert(aactx->colorTemp >= 0);
     assert(aactx->aaTemp >= 0);
  
     /* declare new generic input/texcoord */
     tgsi_transform_input_decl(ctx, aactx->maxInput + 1,
                               TGSI_SEMANTIC_GENERIC, aactx->maxGeneric + 1,
                               TGSI_INTERPOLATE_LINEAR);
  
     /* declare new temp regs */
     tgsi_transform_temp_decl(ctx, aactx->aaTemp);
     tgsi_transform_temp_decl(ctx, aactx->colorTemp);
  }
  
  
  /**
   * TGSI transform epilog callback.
   */
  static void
  aa_transform_epilog(struct tgsi_transform_context *ctx)
  {
     struct aa_transform_context *aactx = (struct aa_transform_context *) ctx;
  
     if (aactx->colorOutput != -1) {
        struct tgsi_full_instruction inst;
        /* insert distance-based coverage code for antialiasing. */
  
        /* saturate(linewidth - fabs(interpx), linelength - fabs(interpz) */
        inst = tgsi_default_full_instruction();
        inst.Instruction.Saturate = true;
        inst.Instruction.Opcode = TGSI_OPCODE_ADD;
        inst.Instruction.NumDstRegs = 1;
        tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_TEMPORARY,
                               aactx->aaTemp, TGSI_WRITEMASK_XZ);
        inst.Instruction.NumSrcRegs = 2;
        tgsi_transform_src_reg(&inst.Src[1], TGSI_FILE_INPUT, aactx->maxInput + 1,
                               TGSI_SWIZZLE_X, TGSI_SWIZZLE_X,
                               TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z);
        tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_INPUT, aactx->maxInput + 1,
                               TGSI_SWIZZLE_Y, TGSI_SWIZZLE_Y,
                               TGSI_SWIZZLE_W, TGSI_SWIZZLE_W);
        inst.Src[1].Register.Absolute = true;
        inst.Src[1].Register.Negate = true;
        ctx->emit_instruction(ctx, &inst);
  
        /* MUL width / height alpha */
        tgsi_transform_op2_swz_inst(ctx, TGSI_OPCODE_MUL,
                                    TGSI_FILE_TEMPORARY, aactx->aaTemp,
                                    TGSI_WRITEMASK_W,
                                    TGSI_FILE_TEMPORARY, aactx->aaTemp,
                                    TGSI_SWIZZLE_X,
                                    TGSI_FILE_TEMPORARY, aactx->aaTemp,
                                    TGSI_SWIZZLE_Z, false);
  
        /* MOV rgb */
        tgsi_transform_op1_inst(ctx, TGSI_OPCODE_MOV,
                                TGSI_FILE_OUTPUT, aactx->colorOutput,
                                TGSI_WRITEMASK_XYZ,
                                TGSI_FILE_TEMPORARY, aactx->colorTemp);
  
        /* MUL alpha */
        tgsi_transform_op2_inst(ctx, TGSI_OPCODE_MUL,
                                TGSI_FILE_OUTPUT, aactx->colorOutput,
                                TGSI_WRITEMASK_W,
                                TGSI_FILE_TEMPORARY, aactx->colorTemp,
                                TGSI_FILE_TEMPORARY, aactx->aaTemp, false);
     }
  }
  
  
  /**
   * TGSI instruction transform callback.
   * Replace writes to result.color w/ a temp reg.
   */
  static void
  aa_transform_inst(struct tgsi_transform_context *ctx,
                    struct tgsi_full_instruction *inst)
  {
     struct aa_transform_context *aactx = (struct aa_transform_context *) ctx;
     uint i;
  
     /*
      * Look for writes to result.color and replace with colorTemp reg.
      */
     for (i = 0; i < inst->Instruction.NumDstRegs; i++) {
        struct tgsi_full_dst_register *dst = &inst->Dst[i];
        if (dst->Register.File == TGSI_FILE_OUTPUT &&
            dst->Register.Index == aactx->colorOutput) {
           dst->Register.File = TGSI_FILE_TEMPORARY;
           dst->Register.Index = aactx->colorTemp;
        }
     }
  
     ctx->emit_instruction(ctx, inst);
  }
  
  
  /**
   * Generate the frag shader we'll use for drawing AA lines.
   * This will be the user's shader plus some arithmetic instructions.
   */
  static boolean
  generate_aaline_fs(struct aaline_stage *aaline)
  {
     struct pipe_context *pipe = aaline->stage.draw->pipe;
     const struct pipe_shader_state *orig_fs = &aaline->fs->state;
     struct pipe_shader_state aaline_fs;
     struct aa_transform_context transform;
     const uint newLen = tgsi_num_tokens(orig_fs->tokens) + NUM_NEW_TOKENS;
  
     aaline_fs = *orig_fs; /* copy to init */
     aaline_fs.tokens = tgsi_alloc_tokens(newLen);
     if (aaline_fs.tokens == NULL)
        return FALSE;
  
     memset(&transform, 0, sizeof(transform));
     transform.colorOutput = -1;
     transform.maxInput = -1;
     transform.maxGeneric = -1;
     transform.colorTemp = -1;
     transform.aaTemp = -1;
     transform.base.prolog = aa_transform_prolog;
     transform.base.epilog = aa_transform_epilog;
     transform.base.transform_instruction = aa_transform_inst;
     transform.base.transform_declaration = aa_transform_decl;
  
     tgsi_transform_shader(orig_fs->tokens,
                           (struct tgsi_token *) aaline_fs.tokens,
                           newLen, &transform.base);
  
  #if 0 /* DEBUG */
     debug_printf("draw_aaline, orig shader:\n");
     tgsi_dump(orig_fs->tokens, 0);
     debug_printf("draw_aaline, new shader:\n");
     tgsi_dump(aaline_fs.tokens, 0);
  #endif
  
     aaline->fs->aaline_fs = aaline->driver_create_fs_state(pipe, &aaline_fs);
     if (aaline->fs->aaline_fs == NULL)
        goto fail;
  
     aaline->fs->generic_attrib = transform.maxGeneric + 1;
     FREE((void *)aaline_fs.tokens);
     return TRUE;
  
  fail:
     FREE((void *)aaline_fs.tokens);
     return FALSE;
  }
  
  
  /**
   * When we're about to draw our first AA line in a batch, this function is
   * called to tell the driver to bind our modified fragment shader.
   */
  static boolean
  bind_aaline_fragment_shader(struct aaline_stage *aaline)
  {
     struct draw_context *draw = aaline->stage.draw;
     struct pipe_context *pipe = draw->pipe;
  
     if (!aaline->fs->aaline_fs && !generate_aaline_fs(aaline))
        return FALSE;
  
     draw->suspend_flushing = TRUE;
     aaline->driver_bind_fs_state(pipe, aaline->fs->aaline_fs);
     draw->suspend_flushing = FALSE;
  
     return TRUE;
  }
  
  
  
  static inline struct aaline_stage *
  aaline_stage(struct draw_stage *stage)
  {
     return (struct aaline_stage *) stage;
  }
  
  
  /**
   * Draw a wide line by drawing a quad, using geometry which will
   * fullfill GL's antialiased line requirements.
   */
  static void
  aaline_line(struct draw_stage *stage, struct prim_header *header)
  {
     const struct aaline_stage *aaline = aaline_stage(stage);
     const float half_width = aaline->half_line_width;
     struct prim_header tri;
     struct vertex_header *v[8];
     uint coordPos = aaline->coord_slot;
     uint posPos = aaline->pos_slot;
     float *pos, *tex;
     float dx = header->v[1]->data[posPos][0] - header->v[0]->data[posPos][0];
     float dy = header->v[1]->data[posPos][1] - header->v[0]->data[posPos][1];
     float a = atan2f(dy, dx);
     float c_a = cosf(a), s_a = sinf(a);
     float half_length;
     float t_l, t_w;
     uint i;
  
     half_length = 0.5f * sqrtf(dx * dx + dy * dy);
  
     if (half_length < 0.5f) {
        /*
         * The logic we use for "normal" sized segments is incorrect
         * for very short segments (basically because we only have
         * one value to interpolate, not a distance to each endpoint).
         * Therefore, we calculate half_length differently, so that for
         * original line length (near) 0, we get alpha 0 - otherwise
         * max alpha would still be 0.5. This also prevents us from
         * artifacts due to degenerated lines (the endpoints being
         * identical, which would still receive anywhere from alpha
         * 0-0.5 otherwise) (at least the pstipple stage may generate
         * such lines due to float inaccuracies if line length is very
         * close to a integer).
         * Might not be fully accurate neither (because the "strength" of
         * the line is going to be determined by how close to the pixel
         * center those 1 or 2 fragments are) but it's probably the best
         * we can do.
         */
        half_length = 2.0f * half_length;
     } else {
        half_length = half_length + 0.5f;
     }
  
     t_w = half_width;
     t_l = 0.5f;
  
     /* allocate/dup new verts */
     for (i = 0; i < 4; i++) {
        v[i] = dup_vert(stage, header->v[i/2], i);
     }
  
     /*
      * Quad strip for line from v0 to v1 (*=endpoints):
      *
      *  1                             3
      *  +-----------------------------+
      *  |                             |
      *  | *v0                     v1* |
      *  |                             |
      *  +-----------------------------+
      *  0                             2
      */
  
     /*
      * We increase line length by 0.5 pixels (at each endpoint),
      * and calculate the tri endpoints by moving them half-width
      * distance away perpendicular to the line.
      * XXX: since we change line endpoints (by 0.5 pixel), should
      * actually re-interpolate all other values?
      */
  
     /* new verts */
     pos = v[0]->data[posPos];
     pos[0] += (-t_l * c_a -  t_w * s_a);
     pos[1] += (-t_l * s_a +  t_w * c_a);
  
     pos = v[1]->data[posPos];
     pos[0] += (-t_l * c_a - -t_w * s_a);
     pos[1] += (-t_l * s_a + -t_w * c_a);
  
     pos = v[2]->data[posPos];
     pos[0] += (t_l * c_a -  t_w * s_a);
     pos[1] += (t_l * s_a +  t_w * c_a);
  
     pos = v[3]->data[posPos];
     pos[0] += (t_l * c_a - -t_w * s_a);
     pos[1] += (t_l * s_a + -t_w * c_a);
  
     /* new texcoords */
     tex = v[0]->data[coordPos];
     ASSIGN_4V(tex, -half_width, half_width, -half_length, half_length);
  
     tex = v[1]->data[coordPos];
     ASSIGN_4V(tex, half_width, half_width, -half_length, half_length);
  
     tex = v[2]->data[coordPos];
     ASSIGN_4V(tex, -half_width, half_width, half_length, half_length);
  
     tex = v[3]->data[coordPos];
     ASSIGN_4V(tex, half_width, half_width, half_length, half_length);
  
     tri.v[0] = v[2];  tri.v[1] = v[1];  tri.v[2] = v[0];
     stage->next->tri(stage->next, &tri);
  
     tri.v[0] = v[3];  tri.v[1] = v[1];  tri.v[2] = v[2];
     stage->next->tri(stage->next, &tri);
  }
  
  
  static void
  aaline_first_line(struct draw_stage *stage, struct prim_header *header)
  {
     auto struct aaline_stage *aaline = aaline_stage(stage);
     struct draw_context *draw = stage->draw;
     struct pipe_context *pipe = draw->pipe;
     const struct pipe_rasterizer_state *rast = draw->rasterizer;
     void *r;
  
     assert(draw->rasterizer->line_smooth);
  
     if (draw->rasterizer->line_width <= 1.0)
        aaline->half_line_width = 1.0;
     else
        aaline->half_line_width = 0.5f * draw->rasterizer->line_width + 0.5f;
  
     if (!draw->rasterizer->half_pixel_center)
        /*
         * The tex coords probably would need adjustments?
         */
        debug_printf("aa lines without half pixel center may be wrong\n");
  
     /*
      * Bind (generate) our fragprog
      */
     if (!bind_aaline_fragment_shader(aaline)) {
        stage->line = draw_pipe_passthrough_line;
        stage->line(stage, header);
        return;
     }
  
     draw_aaline_prepare_outputs(draw, draw->pipeline.aaline);
  
     draw->suspend_flushing = TRUE;
  
     /* Disable triangle culling, stippling, unfilled mode etc. */
     r = draw_get_rasterizer_no_cull(draw, rast->scissor, rast->flatshade);
     pipe->bind_rasterizer_state(pipe, r);
  
     draw->suspend_flushing = FALSE;
  
     /* now really draw first line */
     stage->line = aaline_line;
     stage->line(stage, header);
  }
  
  
  static void
  aaline_flush(struct draw_stage *stage, unsigned flags)
  {
     struct draw_context *draw = stage->draw;
     struct aaline_stage *aaline = aaline_stage(stage);
     struct pipe_context *pipe = draw->pipe;
  
     stage->line = aaline_first_line;
     stage->next->flush(stage->next, flags);
  
     /* restore original frag shader */
     draw->suspend_flushing = TRUE;
     aaline->driver_bind_fs_state(pipe, aaline->fs ? aaline->fs->driver_fs : NULL);
  
     /* restore original rasterizer state */
     if (draw->rast_handle) {
        pipe->bind_rasterizer_state(pipe, draw->rast_handle);
     }
  
     draw->suspend_flushing = FALSE;
  
     draw_remove_extra_vertex_attribs(draw);
  }
  
  
  static void
  aaline_reset_stipple_counter(struct draw_stage *stage)
  {
     stage->next->reset_stipple_counter(stage->next);
  }
  
  
  static void
  aaline_destroy(struct draw_stage *stage)
  {
     struct aaline_stage *aaline = aaline_stage(stage);
     struct pipe_context *pipe = stage->draw->pipe;
  
     draw_free_temp_verts(stage);
  
     /* restore the old entry points */
     pipe->create_fs_state = aaline->driver_create_fs_state;
     pipe->bind_fs_state = aaline->driver_bind_fs_state;
     pipe->delete_fs_state = aaline->driver_delete_fs_state;
  
     FREE(stage);
  }
  
  
  static struct aaline_stage *
  draw_aaline_stage(struct draw_context *draw)
  {
     struct aaline_stage *aaline = CALLOC_STRUCT(aaline_stage);
     if (!aaline)
        return NULL;
  
     aaline->stage.draw = draw;
     aaline->stage.name = "aaline";
     aaline->stage.next = NULL;
     aaline->stage.point = draw_pipe_passthrough_point;
     aaline->stage.line = aaline_first_line;
     aaline->stage.tri = draw_pipe_passthrough_tri;
     aaline->stage.flush = aaline_flush;
     aaline->stage.reset_stipple_counter = aaline_reset_stipple_counter;
     aaline->stage.destroy = aaline_destroy;
  
     if (!draw_alloc_temp_verts(&aaline->stage, 8))
        goto fail;
  
     return aaline;
  
   fail:
     aaline->stage.destroy(&aaline->stage);
  
     return NULL;
  }
  
  
  static struct aaline_stage *
  aaline_stage_from_pipe(struct pipe_context *pipe)
  {
     struct draw_context *draw = (struct draw_context *) pipe->draw;
  
     if (draw) {
        return aaline_stage(draw->pipeline.aaline);
     } else {
        return NULL;
     }
  }
  
  
  /**
   * This function overrides the driver's create_fs_state() function and
   * will typically be called by the state tracker.
   */
  static void *
  aaline_create_fs_state(struct pipe_context *pipe,
                         const struct pipe_shader_state *fs)
  {
     struct aaline_stage *aaline = aaline_stage_from_pipe(pipe);
     struct aaline_fragment_shader *aafs = NULL;
  
     if (!aaline)
        return NULL;
  
     aafs = CALLOC_STRUCT(aaline_fragment_shader);
  
     if (!aafs)
        return NULL;
  
     aafs->state.tokens = tgsi_dup_tokens(fs->tokens);
  
     /* pass-through */
     aafs->driver_fs = aaline->driver_create_fs_state(pipe, fs);
  
     return aafs;
  }
  
  
  static void
  aaline_bind_fs_state(struct pipe_context *pipe, void *fs)
  {
     struct aaline_stage *aaline = aaline_stage_from_pipe(pipe);
     struct aaline_fragment_shader *aafs = (struct aaline_fragment_shader *) fs;
  
     if (!aaline) {
        return;
     }
  
     /* save current */
     aaline->fs = aafs;
     /* pass-through */
     aaline->driver_bind_fs_state(pipe, (aafs ? aafs->driver_fs : NULL));
  }
  
  
  static void
  aaline_delete_fs_state(struct pipe_context *pipe, void *fs)
  {
     struct aaline_stage *aaline = aaline_stage_from_pipe(pipe);
     struct aaline_fragment_shader *aafs = (struct aaline_fragment_shader *) fs;
  
     if (!aafs) {
        return;
     }
  
     if (aaline) {
        /* pass-through */
        aaline->driver_delete_fs_state(pipe, aafs->driver_fs);
  
        if (aafs->aaline_fs)
           aaline->driver_delete_fs_state(pipe, aafs->aaline_fs);
     }
  
     FREE((void*)aafs->state.tokens);
     FREE(aafs);
  }
  
  
  void
  draw_aaline_prepare_outputs(struct draw_context *draw,
                              struct draw_stage *stage)
  {
     struct aaline_stage *aaline = aaline_stage(stage);
     const struct pipe_rasterizer_state *rast = draw->rasterizer;
  
     /* update vertex attrib info */
     aaline->pos_slot = draw_current_shader_position_output(draw);
  
     if (!rast->line_smooth)
        return;
  
     /* allocate the extra post-transformed vertex attribute */
     aaline->coord_slot = draw_alloc_extra_vertex_attrib(draw,
                                                       TGSI_SEMANTIC_GENERIC,
                                                       aaline->fs->generic_attrib);
  }
  
  /**
   * Called by drivers that want to install this AA line prim stage
   * into the draw module's pipeline.  This will not be used if the
   * hardware has native support for AA lines.
   */
  boolean
  draw_install_aaline_stage(struct draw_context *draw, struct pipe_context *pipe)
  {
     struct aaline_stage *aaline;
  
     pipe->draw = (void *) draw;
  
     /*
      * Create / install AA line drawing / prim stage
      */
     aaline = draw_aaline_stage(draw);
     if (!aaline)
        goto fail;
  
     /* save original driver functions */
     aaline->driver_create_fs_state = pipe->create_fs_state;
     aaline->driver_bind_fs_state = pipe->bind_fs_state;
     aaline->driver_delete_fs_state = pipe->delete_fs_state;
  
     /* override the driver's functions */
     pipe->create_fs_state = aaline_create_fs_state;
     pipe->bind_fs_state = aaline_bind_fs_state;
     pipe->delete_fs_state = aaline_delete_fs_state;
  
     /* Install once everything is known to be OK:
      */
     draw->pipeline.aaline = &aaline->stage;
  
     return TRUE;
  
  fail:
     if (aaline)
        aaline->stage.destroy(&aaline->stage);
  
     return FALSE;
  }
  