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
33#include "t_context.h"
34#include "t_pipeline.h"
35
36
37struct 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 */
50static GLboolean
51run_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
80static GLboolean
81alloc_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
95static void
96free_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
107const 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