src/mesa/tnl/t_vb_points.c

   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 "mtypes.h"
  29 #include "imports.h"
  30 #include "t_context.h"
  31 #include "t_pipeline.h"
  32
  33
  34 struct point_stage_data {
  35    GLvector4f PointSize;
  36 };
  37
  38 #define POINT_STAGE_DATA(stage) ((struct point_stage_data *)stage->privatePtr)
  39
  40
  41 /**
  42  * Compute point size for each vertex from the vertex eye-space Z
  43  * coordinate and the point size attenuation factors.
  44  * Only done when point size attenuation is enabled and vertex program is
  45  * disabled.
  46  */
  47 static GLboolean
  48 run_point_stage(GLcontext *ctx, struct tnl_pipeline_stage *stage)
  49 {
  50    if (ctx->Point._Attenuated && !ctx->VertexProgram._Current) {
  51       struct point_stage_data *store = POINT_STAGE_DATA(stage);
  52       struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  53       const GLfloat *eyeCoord = (GLfloat *) VB->EyePtr->data + 2;
  54       const GLint eyeCoordStride = VB->EyePtr->stride / sizeof(GLfloat);
  55       const GLfloat p0 = ctx->Point.Params[0];
  56       const GLfloat p1 = ctx->Point.Params[1];
  57       const GLfloat p2 = ctx->Point.Params[2];
  58       const GLfloat pointSize = ctx->Point.Size;
  59       GLfloat (*size)[4] = store->PointSize.data;
  60       GLuint i;
  61
  62       for (i = 0; i < VB->Count; i++) {
  63          const GLfloat dist = FABSF(*eyeCoord);
  64          const GLfloat q = p0 + dist * (p1 + dist * p2);
  65          const GLfloat atten = (q != 0.0) ? SQRTF(1.0 / q) : 1.0;
  66          size[i][0] = pointSize * atten; /* clamping done in rasterization */
  67          eyeCoord += eyeCoordStride;
  68       }
  69
  70       VB->AttribPtr[_TNL_ATTRIB_POINTSIZE] = &store->PointSize;
  71    }
  72
  73    return GL_TRUE;
  74 }
  75
  76
  77 static GLboolean
  78 alloc_point_data(GLcontext *ctx, struct tnl_pipeline_stage *stage)
  79 {
  80    struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
  81    struct point_stage_data *store;
  82    stage->privatePtr = _mesa_malloc(sizeof(*store));
  83    store = POINT_STAGE_DATA(stage);
  84    if (!store)
  85       return GL_FALSE;
  86
  87    _mesa_vector4f_alloc( &store->PointSize, 0, VB->Size, 32 );
  88    return GL_TRUE;
  89 }
  90
  91
  92 static void
  93 free_point_data(struct tnl_pipeline_stage *stage)
  94 {
  95    struct point_stage_data *store = POINT_STAGE_DATA(stage);
  96    if (store) {
  97       _mesa_vector4f_free( &store->PointSize );
  98       _mesa_free( store );
  99       stage->privatePtr = NULL;
 100    }
 101 }
 102
 103
 104 const struct tnl_pipeline_stage _tnl_point_attenuation_stage =
 105 {
 106    "point size attenuation",    /* name */
 107    NULL,                        /* stage private data */
 108    alloc_point_data,            /* alloc data */
 109    free_point_data,             /* destructor */
 110    NULL,
 111    run_point_stage              /* run */
 112 };