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  1. /*
  2.  * Mesa 3-D graphics library
  3.  * Version:  7.0
  4.  *
  5.  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
  6.  *
  7.  * Permission is hereby granted, free of charge, to any person obtaining a
  8.  * copy of this software and associated documentation files (the "Software"),
  9.  * to deal in the Software without restriction, including without limitation
  10.  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11.  * and/or sell copies of the Software, and to permit persons to whom the
  12.  * Software is furnished to do so, subject to the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice shall be included
  15.  * in all copies or substantial portions of the Software.
  16.  *
  17.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18.  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20.  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21.  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22.  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23.  *
  24.  * Authors:
  25.  *    Brian Paul
  26.  */
  27.  
  28. #include "main/glheader.h"
  29. #include "main/mtypes.h"
  30. #include "main/dd.h"
  31. #include "main/imports.h"
  32. #include "t_context.h"
  33. #include "t_pipeline.h"
  34.  
  35.  
  36. struct point_stage_data {
  37.    GLvector4f PointSize;
  38. };
  39.  
  40. #define POINT_STAGE_DATA(stage) ((struct point_stage_data *)stage->privatePtr)
  41.  
  42.  
  43. /**
  44.  * Compute point size for each vertex from the vertex eye-space Z
  45.  * coordinate and the point size attenuation factors.
  46.  * Only done when point size attenuation is enabled and vertex program is
  47.  * disabled.
  48.  */
  49. static GLboolean
  50. run_point_stage(struct gl_context *ctx, struct tnl_pipeline_stage *stage)
  51. {
  52.    if (ctx->Point._Attenuated && !ctx->VertexProgram._Current) {
  53.       struct point_stage_data *store = POINT_STAGE_DATA(stage);
  54.       struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  55.       const GLfloat *eyeCoord = (GLfloat *) VB->EyePtr->data + 2;
  56.       const GLint eyeCoordStride = VB->EyePtr->stride / sizeof(GLfloat);
  57.       const GLfloat p0 = ctx->Point.Params[0];
  58.       const GLfloat p1 = ctx->Point.Params[1];
  59.       const GLfloat p2 = ctx->Point.Params[2];
  60.       const GLfloat pointSize = ctx->Point.Size;
  61.       GLfloat (*size)[4] = store->PointSize.data;
  62.       GLuint i;
  63.  
  64.       for (i = 0; i < VB->Count; i++) {
  65.          const GLfloat dist = FABSF(*eyeCoord);
  66.          const GLfloat q = p0 + dist * (p1 + dist * p2);
  67.          const GLfloat atten = (q != 0.0F) ? SQRTF(1.0F / q) : 1.0F;
  68.          size[i][0] = pointSize * atten; /* clamping done in rasterization */
  69.          eyeCoord += eyeCoordStride;
  70.       }
  71.  
  72.       VB->AttribPtr[_TNL_ATTRIB_POINTSIZE] = &store->PointSize;
  73.    }
  74.  
  75.    return GL_TRUE;
  76. }
  77.  
  78.  
  79. static GLboolean
  80. alloc_point_data(struct gl_context *ctx, struct tnl_pipeline_stage *stage)
  81. {
  82.    struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  83.    struct point_stage_data *store;
  84.    stage->privatePtr = malloc(sizeof(*store));
  85.    store = POINT_STAGE_DATA(stage);
  86.    if (!store)
  87.       return GL_FALSE;
  88.  
  89.    _mesa_vector4f_alloc( &store->PointSize, 0, VB->Size, 32 );
  90.    return GL_TRUE;
  91. }
  92.  
  93.  
  94. static void
  95. free_point_data(struct tnl_pipeline_stage *stage)
  96. {
  97.    struct point_stage_data *store = POINT_STAGE_DATA(stage);
  98.    if (store) {
  99.       _mesa_vector4f_free( &store->PointSize );
  100.       free( store );
  101.       stage->privatePtr = NULL;
  102.    }
  103. }
  104.  
  105.  
  106. const struct tnl_pipeline_stage _tnl_point_attenuation_stage =
  107. {
  108.    "point size attenuation",    /* name */
  109.    NULL,                        /* stage private data */
  110.    alloc_point_data,            /* alloc data */
  111.    free_point_data,             /* destructor */
  112.    NULL,
  113.    run_point_stage              /* run */
  114. };
  115.