t_vb_fog.c revision 30f51ae067379c2b3573c06b707d25a9704df7be 
1/* $Id: t_vb_fog.c,v 1.14 2001/12/18 04:06:46 brianp Exp $ */
2
3/*
4 * Mesa 3-D graphics library
5 * Version:  3.5
6 *
7 * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included
17 * in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
22 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
23 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 * Authors:
27 *    Keith Whitwell <keithw@valinux.com>
28 */
29
30
31#include "glheader.h"
32#include "colormac.h"
33#include "context.h"
34#include "macros.h"
35#include "mem.h"
36#include "mmath.h"
37#include "mtypes.h"
38
39#include "math/m_xform.h"
40
41#include "t_context.h"
42#include "t_pipeline.h"
43
44
45struct fog_stage_data {
46   GLvector1f fogcoord;		/* has actual storage allocated */
47   GLvector1f input;		/* points into VB->EyePtr Z values */
48};
49
50#define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->privatePtr)
51
52#define FOG_EXP_TABLE_SIZE 256
53#define FOG_MAX (10.0)
54#define EXP_FOG_MAX .0006595
55#define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE)
56static GLfloat exp_table[FOG_EXP_TABLE_SIZE];
57static GLfloat inited = 0;
58
59#if 1
60#define NEG_EXP( result, narg )						\
61do {									\
62   GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR));			\
63   GLint k = (GLint) f;							\
64   if (k > FOG_EXP_TABLE_SIZE-2) 					\
65      result = (GLfloat) EXP_FOG_MAX;					\
66   else									\
67      result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]);	\
68} while (0)
69#else
70#define NEG_EXP( result, narg )					\
71do {								\
72   result = exp(-narg);						\
73} while (0)
74#endif
75
76
77static void init_static_data( void )
78{
79   GLfloat f = 0.0F;
80   GLint i = 0;
81   for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) {
82      exp_table[i] = (GLfloat) exp(-f);
83   }
84   inited = 1;
85}
86
87
88static void make_win_fog_coords( GLcontext *ctx, GLvector1f *out,
89				 const GLvector1f *in )
90{
91   GLfloat end  = ctx->Fog.End;
92   GLfloat *v = in->start;
93   GLuint stride = in->stride;
94   GLuint n = in->count;
95   GLfloat *data = out->data;
96   GLfloat d;
97   GLuint i;
98
99   out->count = in->count;
100
101   switch (ctx->Fog.Mode) {
102   case GL_LINEAR:
103      if (ctx->Fog.Start == ctx->Fog.End)
104         d = 1.0F;
105      else
106         d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
107      for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
108         GLfloat f = (end - ABSF(*v)) * d;
109	 data[i] = CLAMP(f, 0.0F, 1.0F);
110      }
111      break;
112   case GL_EXP:
113      d = ctx->Fog.Density;
114      for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride))
115         NEG_EXP( data[i], d * ABSF(*v) );
116      break;
117   case GL_EXP2:
118      d = ctx->Fog.Density*ctx->Fog.Density;
119      for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
120         GLfloat z = *v;
121         NEG_EXP( data[i], d * z * z );
122      }
123      break;
124   default:
125      _mesa_problem(ctx, "Bad fog mode in make_fog_coord");
126      return;
127   }
128}
129
130
131static GLboolean run_fog_stage( GLcontext *ctx,
132				struct gl_pipeline_stage *stage )
133{
134   struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
135   struct fog_stage_data *store = FOG_STAGE_DATA(stage);
136   GLvector1f *input;
137
138   if (stage->changed_inputs == 0)
139      return GL_TRUE;
140
141   if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT) {
142      /* fog computed from Z depth */
143      /* source = VB->ObjPtr or VB->EyePtr coords */
144      /* dest = VB->FogCoordPtr = fog stage private storage */
145      VB->FogCoordPtr = &store->fogcoord;
146
147      if (!ctx->_NeedEyeCoords) {
148	 const GLfloat *m = ctx->ModelviewMatrixStack.Top->m;
149	 GLfloat plane[4];
150
151	 /* Use this to store calculated eye z values:
152	  */
153	 input = &store->fogcoord;
154
155	 plane[0] = m[2];
156	 plane[1] = m[6];
157	 plane[2] = m[10];
158	 plane[3] = m[14];
159
160	 /* Full eye coords weren't required, just calculate the
161	  * eye Z values.
162	  */
163	 _mesa_dotprod_tab[VB->ObjPtr->size]( input->data,
164					      sizeof(GLfloat),
165					      VB->ObjPtr, plane );
166
167	 input->count = VB->ObjPtr->count;
168      }
169      else {
170	 input = &store->input;
171
172	 if (VB->EyePtr->size < 2)
173	    _mesa_vector4f_clean_elem( VB->EyePtr, VB->Count, 2 );
174
175	 input->data = &(VB->EyePtr->data[0][2]);
176	 input->start = VB->EyePtr->start+2;
177	 input->stride = VB->EyePtr->stride;
178	 input->count = VB->EyePtr->count;
179      }
180   }
181   else {
182      /* use glFogCoord() coordinates */
183      /* source = VB->FogCoordPtr */
184      input = VB->FogCoordPtr;
185      /* dest = fog stage private storage */
186      VB->FogCoordPtr = &store->fogcoord;
187   }
188
189   make_win_fog_coords( ctx, VB->FogCoordPtr, input );
190   return GL_TRUE;
191}
192
193
194static void check_fog_stage( GLcontext *ctx, struct gl_pipeline_stage *stage )
195{
196   stage->active = ctx->Fog.Enabled && !ctx->VertexProgram.Enabled;
197
198   if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT)
199      stage->inputs = VERT_EYE;
200   else
201      stage->inputs = VERT_FOG_BIT;
202}
203
204
205/* Called the first time stage->run() is invoked.
206 */
207static GLboolean alloc_fog_data( GLcontext *ctx,
208				 struct gl_pipeline_stage *stage )
209{
210   TNLcontext *tnl = TNL_CONTEXT(ctx);
211   struct fog_stage_data *store;
212   stage->privatePtr = MALLOC(sizeof(*store));
213   store = FOG_STAGE_DATA(stage);
214   if (!store)
215      return GL_FALSE;
216
217   _mesa_vector1f_alloc( &store->fogcoord, 0, tnl->vb.Size, 32 );
218   _mesa_vector1f_init( &store->input, 0, 0 );
219
220   if (!inited)
221      init_static_data();
222
223   /* Now run the stage.
224    */
225   stage->run = run_fog_stage;
226   return stage->run( ctx, stage );
227}
228
229
230static void free_fog_data( struct gl_pipeline_stage *stage )
231{
232   struct fog_stage_data *store = FOG_STAGE_DATA(stage);
233   if (store) {
234      _mesa_vector1f_free( &store->fogcoord );
235      FREE( store );
236      stage->privatePtr = NULL;
237   }
238}
239
240
241const struct gl_pipeline_stage _tnl_fog_coordinate_stage =
242{
243   "build fog coordinates",	/* name */
244   _NEW_FOG,			/* check_state */
245   _NEW_FOG,			/* run_state */
246   GL_FALSE,			/* active? */
247   0,				/* inputs */
248   VERT_FOG_BIT,		/* outputs */
249   0,				/* changed_inputs */
250   NULL,			/* private_data */
251   free_fog_data,		/* dtr */
252   check_fog_stage,		/* check */
253   alloc_fog_data		/* run -- initially set to init. */
254};
255