src/mesa/tnl/t_vb_points.c

   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 };