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  1. /*
  2.  * Mesa 3-D graphics library
  3.  *
  4.  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
  5.  *
  6.  * Permission is hereby granted, free of charge, to any person obtaining a
  7.  * copy of this software and associated documentation files (the "Software"),
  8.  * to deal in the Software without restriction, including without limitation
  9.  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10.  * and/or sell copies of the Software, and to permit persons to whom the
  11.  * Software is furnished to do so, subject to the following conditions:
  12.  *
  13.  * The above copyright notice and this permission notice shall be included
  14.  * in all copies or substantial portions of the Software.
  15.  *
  16.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  17.  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20.  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21.  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22.  * OTHER DEALINGS IN THE SOFTWARE.
  23.  *
  24.  * Authors:
  25.  *    Brian Paul
  26.  */
  27.  
  28. #include "c99_math.h"
  29. #include "main/glheader.h"
  30. #include "main/mtypes.h"
  31. #include "main/dd.h"
  32. #include "main/imports.h"
  33. #include "t_context.h"
  34. #include "t_pipeline.h"
  35.  
  36.  
  37. struct point_stage_data {
  38.    GLvector4f PointSize;
  39. };
  40.  
  41. #define POINT_STAGE_DATA(stage) ((struct point_stage_data *)stage->privatePtr)
  42.  
  43.  
  44. /**
  45.  * Compute point size for each vertex from the vertex eye-space Z
  46.  * coordinate and the point size attenuation factors.
  47.  * Only done when point size attenuation is enabled and vertex program is
  48.  * disabled.
  49.  */
  50. static GLboolean
  51. run_point_stage(struct gl_context *ctx, struct tnl_pipeline_stage *stage)
  52. {
  53.    if (ctx->Point._Attenuated && !ctx->VertexProgram._Current) {
  54.       struct point_stage_data *store = POINT_STAGE_DATA(stage);
  55.       struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  56.       const GLfloat *eyeCoord = (GLfloat *) VB->EyePtr->data + 2;
  57.       const GLint eyeCoordStride = VB->EyePtr->stride / sizeof(GLfloat);
  58.       const GLfloat p0 = ctx->Point.Params[0];
  59.       const GLfloat p1 = ctx->Point.Params[1];
  60.       const GLfloat p2 = ctx->Point.Params[2];
  61.       const GLfloat pointSize = ctx->Point.Size;
  62.       GLfloat (*size)[4] = store->PointSize.data;
  63.       GLuint i;
  64.  
  65.       for (i = 0; i < VB->Count; i++) {
  66.          const GLfloat dist = fabsf(*eyeCoord);
  67.          const GLfloat q = p0 + dist * (p1 + dist * p2);
  68.          const GLfloat atten = (q != 0.0F) ? (1.0f / sqrtf(q)) : 1.0F;
  69.          size[i][0] = pointSize * atten; /* clamping done in rasterization */
  70.          eyeCoord += eyeCoordStride;
  71.       }
  72.  
  73.       VB->AttribPtr[_TNL_ATTRIB_POINTSIZE] = &store->PointSize;
  74.    }
  75.  
  76.    return GL_TRUE;
  77. }
  78.  
  79.  
  80. static GLboolean
  81. alloc_point_data(struct gl_context *ctx, struct tnl_pipeline_stage *stage)
  82. {
  83.    struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  84.    struct point_stage_data *store;
  85.    stage->privatePtr = malloc(sizeof(*store));
  86.    store = POINT_STAGE_DATA(stage);
  87.    if (!store)
  88.       return GL_FALSE;
  89.  
  90.    _mesa_vector4f_alloc( &store->PointSize, 0, VB->Size, 32 );
  91.    return GL_TRUE;
  92. }
  93.  
  94.  
  95. static void
  96. free_point_data(struct tnl_pipeline_stage *stage)
  97. {
  98.    struct point_stage_data *store = POINT_STAGE_DATA(stage);
  99.    if (store) {
  100.       _mesa_vector4f_free( &store->PointSize );
  101.       free( store );
  102.       stage->privatePtr = NULL;
  103.    }
  104. }
  105.  
  106.  
  107. const struct tnl_pipeline_stage _tnl_point_attenuation_stage =
  108. {
  109.    "point size attenuation",    /* name */
  110.    NULL,                        /* stage private data */
  111.    alloc_point_data,            /* alloc data */
  112.    free_point_data,             /* destructor */
  113.    NULL,
  114.    run_point_stage              /* run */
  115. };
  116.