src/mesa/tnl/t_vb_fog.c

   1
   2 /*
   3  * Mesa 3-D graphics library
   4  * Version:  5.1
   5  *
   6  * Copyright (C) 1999-2003  Brian Paul   All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  * Authors:
  26  *    Keith Whitwell <keith@tungstengraphics.com>
  27  */
  28
  29
  30 #include "glheader.h"
  31 #include "colormac.h"
  32 #include "context.h"
  33 #include "macros.h"
  34 #include "imports.h"
  35 #include "mtypes.h"
  36
  37 #include "math/m_xform.h"
  38
  39 #include "t_context.h"
  40 #include "t_pipeline.h"
  41
  42
  43 struct fog_stage_data {
  44    GLvector4f fogcoord;         /* has actual storage allocated */
  45    GLvector4f input;            /* points into VB->EyePtr Z values */
  46 };
  47
  48 #define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->privatePtr)
  49
  50 #define FOG_EXP_TABLE_SIZE 256
  51 #define FOG_MAX (10.0)
  52 #define EXP_FOG_MAX .0006595
  53 #define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE)
  54 static GLfloat exp_table[FOG_EXP_TABLE_SIZE];
  55 static GLfloat inited = 0;
  56
  57 #if 1
  58 #define NEG_EXP( result, narg )                                         \
  59 do {                                                                    \
  60    GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR));                       \
  61    GLint k = (GLint) f;                                                 \
  62    if (k > FOG_EXP_TABLE_SIZE-2)                                        \
  63       result = (GLfloat) EXP_FOG_MAX;                                   \
  64    else                                                                 \
  65       result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]);      \
  66 } while (0)
  67 #else
  68 #define NEG_EXP( result, narg )                                 \
  69 do {                                                            \
  70    result = exp(-narg);                                         \
  71 } while (0)
  72 #endif
  73
  74
  75 static void init_static_data( void )
  76 {
  77    GLfloat f = 0.0F;
  78    GLint i = 0;
  79    for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) {
  80       exp_table[i] = (GLfloat) exp(-f);
  81    }
  82    inited = 1;
  83 }
  84
  85
  86 static void make_win_fog_coords( GLcontext *ctx, GLvector4f *out,
  87                                  const GLvector4f *in )
  88 {
  89    GLfloat end  = ctx->Fog.End;
  90    GLfloat *v = in->start;
  91    GLuint stride = in->stride;
  92    GLuint n = in->count;
  93    GLfloat (*data)[4] = out->data;
  94    GLfloat d;
  95    GLuint i;
  96
  97    out->count = in->count;
  98
  99    switch (ctx->Fog.Mode) {
 100    case GL_LINEAR:
 101       if (ctx->Fog.Start == ctx->Fog.End)
 102          d = 1.0F;
 103       else
 104          d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
 105       for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
 106          GLfloat f = (end - FABSF(*v)) * d;
 107          data[i][0] = CLAMP(f, 0.0F, 1.0F);
 108       }
 109       break;
 110    case GL_EXP:
 111       d = ctx->Fog.Density;
 112       for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride))
 113          NEG_EXP( data[i][0], d * FABSF(*v) );
 114       break;
 115    case GL_EXP2:
 116       d = ctx->Fog.Density*ctx->Fog.Density;
 117       for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
 118          GLfloat z = *v;
 119          NEG_EXP( data[i][0], d * z * z );
 120       }
 121       break;
 122    default:
 123       _mesa_problem(ctx, "Bad fog mode in make_fog_coord");
 124       return;
 125    }
 126 }
 127
 128
 129 static GLboolean run_fog_stage( GLcontext *ctx,
 130                                 struct tnl_pipeline_stage *stage )
 131 {
 132    struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb;
 133    struct fog_stage_data *store = FOG_STAGE_DATA(stage);
 134    GLvector4f *input;
 135
 136    if (stage->changed_inputs == 0)
 137       return GL_TRUE;
 138
 139    if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT) {
 140       /* fog computed from Z depth */
 141       /* source = VB->ObjPtr or VB->EyePtr coords */
 142       /* dest = VB->FogCoordPtr = fog stage private storage */
 143       VB->FogCoordPtr = &store->fogcoord;
 144
 145       if (!ctx->_NeedEyeCoords) {
 146          const GLfloat *m = ctx->ModelviewMatrixStack.Top->m;
 147          GLfloat plane[4];
 148
 149          /* Use this to store calculated eye z values:
 150           */
 151          input = &store->fogcoord;
 152
 153          plane[0] = m[2];
 154          plane[1] = m[6];
 155          plane[2] = m[10];
 156          plane[3] = m[14];
 157
 158          /* Full eye coords weren't required, just calculate the
 159           * eye Z values.
 160           */
 161          _mesa_dotprod_tab[VB->ObjPtr->size]( (GLfloat *) input->data,
 162                                               4 * sizeof(GLfloat),
 163                                               VB->ObjPtr, plane );
 164
 165          input->count = VB->ObjPtr->count;
 166       }
 167       else {
 168          input = &store->input;
 169
 170          if (VB->EyePtr->size < 2)
 171             _mesa_vector4f_clean_elem( VB->EyePtr, VB->Count, 2 );
 172
 173          input->data = (GLfloat (*)[4]) &(VB->EyePtr->data[0][2]);
 174          input->start = VB->EyePtr->start+2;
 175          input->stride = VB->EyePtr->stride;
 176          input->count = VB->EyePtr->count;
 177       }
 178    }
 179    else {
 180       /* use glFogCoord() coordinates */
 181       /* source = VB->FogCoordPtr */
 182       input = VB->FogCoordPtr;
 183       /* dest = fog stage private storage */
 184       VB->FogCoordPtr = &store->fogcoord;
 185    }
 186
 187    make_win_fog_coords( ctx, VB->FogCoordPtr, input );
 188    return GL_TRUE;
 189 }
 190
 191
 192 static void check_fog_stage( GLcontext *ctx, struct tnl_pipeline_stage *stage )
 193 {
 194    stage->active = ctx->Fog.Enabled && !ctx->VertexProgram.Enabled;
 195
 196    if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT)
 197       stage->inputs = _TNL_BIT_POS;
 198    else
 199       stage->inputs = _TNL_BIT_FOG;
 200 }
 201
 202
 203 /* Called the first time stage->run() is invoked.
 204  */
 205 static GLboolean alloc_fog_data( GLcontext *ctx,
 206                                  struct tnl_pipeline_stage *stage )
 207 {
 208    TNLcontext *tnl = TNL_CONTEXT(ctx);
 209    struct fog_stage_data *store;
 210    stage->privatePtr = MALLOC(sizeof(*store));
 211    store = FOG_STAGE_DATA(stage);
 212    if (!store)
 213       return GL_FALSE;
 214
 215    _mesa_vector4f_alloc( &store->fogcoord, 0, tnl->vb.Size, 32 );
 216    _mesa_vector4f_init( &store->input, 0, 0 );
 217
 218    if (!inited)
 219       init_static_data();
 220
 221    /* Now run the stage.
 222     */
 223    stage->run = run_fog_stage;
 224    return stage->run( ctx, stage );
 225 }
 226
 227
 228 static void free_fog_data( struct tnl_pipeline_stage *stage )
 229 {
 230    struct fog_stage_data *store = FOG_STAGE_DATA(stage);
 231    if (store) {
 232       _mesa_vector4f_free( &store->fogcoord );
 233       FREE( store );
 234       stage->privatePtr = NULL;
 235    }
 236 }
 237
 238
 239 const struct tnl_pipeline_stage _tnl_fog_coordinate_stage =
 240 {
 241    "build fog coordinates",     /* name */
 242    _NEW_FOG,                    /* check_state */
 243    _NEW_FOG,                    /* run_state */
 244    GL_FALSE,                    /* active? */
 245    0,                           /* inputs */
 246    _TNL_BIT_FOG,                /* outputs */
 247    0,                           /* changed_inputs */
 248    NULL,                        /* private_data */
 249    free_fog_data,               /* dtr */
 250    check_fog_stage,             /* check */
 251    alloc_fog_data               /* run -- initially set to init. */
 252 };