/* * Mesa 3-D graphics library * * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Authors: * Keith Whitwell */ #include "c99_math.h" #include "main/glheader.h" #include "main/macros.h" #include "main/imports.h" #include "main/mtypes.h" #include "math/m_xform.h" #include "t_context.h" #include "t_pipeline.h" struct fog_stage_data { GLvector4f fogcoord; /* has actual storage allocated */ }; #define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->privatePtr) #define FOG_EXP_TABLE_SIZE 256 #define FOG_MAX (10.0F) #define EXP_FOG_MAX .0006595F #define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE) static GLfloat exp_table[FOG_EXP_TABLE_SIZE]; static GLfloat inited = 0; #if 1 #define NEG_EXP( result, narg ) \ do { \ GLfloat f = (GLfloat) (narg * (1.0F / FOG_INCR)); \ GLint k = (GLint) f; \ if (k > FOG_EXP_TABLE_SIZE-2) \ result = (GLfloat) EXP_FOG_MAX; \ else \ result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \ } while (0) #else #define NEG_EXP( result, narg ) \ do { \ result = exp(-narg); \ } while (0) #endif /** * Initialize the exp_table[] lookup table for approximating exp(). */ static void init_static_data( void ) { GLfloat f = 0.0F; GLint i = 0; for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) { exp_table[i] = expf(-f); } inited = 1; } /** * Compute per-vertex fog blend factors from fog coordinates by * evaluating the GL_LINEAR, GL_EXP or GL_EXP2 fog function. * Fog coordinates are distances from the eye (typically between the * near and far clip plane distances). * Note that fogcoords may be negative, if eye z is source absolute * value must be taken earlier. * Fog blend factors are in the range [0,1]. */ static void compute_fog_blend_factors(struct gl_context *ctx, GLvector4f *out, const GLvector4f *in) { GLfloat end = ctx->Fog.End; GLfloat *v = in->start; GLuint stride = in->stride; GLuint n = in->count; GLfloat (*data)[4] = out->data; GLfloat d; GLuint i; out->count = in->count; switch (ctx->Fog.Mode) { case GL_LINEAR: if (ctx->Fog.Start == ctx->Fog.End) d = 1.0F; else d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) { const GLfloat z = *v; GLfloat f = (end - z) * d; data[i][0] = CLAMP(f, 0.0F, 1.0F); } break; case GL_EXP: d = ctx->Fog.Density; for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride)) { const GLfloat z = *v; NEG_EXP( data[i][0], d * z ); } break; case GL_EXP2: d = ctx->Fog.Density*ctx->Fog.Density; for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) { const GLfloat z = *v; NEG_EXP( data[i][0], d * z * z ); } break; default: _mesa_problem(ctx, "Bad fog mode in make_fog_coord"); return; } } static GLboolean run_fog_stage(struct gl_context *ctx, struct tnl_pipeline_stage *stage) { TNLcontext *tnl = TNL_CONTEXT(ctx); struct vertex_buffer *VB = &tnl->vb; struct fog_stage_data *store = FOG_STAGE_DATA(stage); GLvector4f *input; if (!ctx->Fog.Enabled) return GL_TRUE; if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT && !ctx->VertexProgram._Current) { GLuint i; GLfloat *coord; /* Fog is computed from vertex or fragment Z values */ /* source = VB->AttribPtr[_TNL_ATTRIB_POS] or VB->EyePtr coords */ /* dest = VB->AttribPtr[_TNL_ATTRIB_FOG] = fog stage private storage */ VB->AttribPtr[_TNL_ATTRIB_FOG] = &store->fogcoord; if (!ctx->_NeedEyeCoords) { /* compute fog coords from object coords */ const GLfloat *m = ctx->ModelviewMatrixStack.Top->m; GLfloat plane[4]; /* Use this to store calculated eye z values: */ input = &store->fogcoord; plane[0] = m[2]; plane[1] = m[6]; plane[2] = m[10]; plane[3] = m[14]; /* Full eye coords weren't required, just calculate the * eye Z values. */ _mesa_dotprod_tab[VB->AttribPtr[_TNL_ATTRIB_POS]->size] ( (GLfloat *) input->data, 4 * sizeof(GLfloat), VB->AttribPtr[_TNL_ATTRIB_POS], plane ); input->count = VB->AttribPtr[_TNL_ATTRIB_POS]->count; /* make sure coords are really positive NOTE should avoid going through array twice */ coord = input->start; for (i = 0; i < input->count; i++) { *coord = fabsf(*coord); STRIDE_F(coord, input->stride); } } else { /* fog coordinates = eye Z coordinates - need to copy for ABS */ input = &store->fogcoord; if (VB->EyePtr->size < 2) _mesa_vector4f_clean_elem( VB->EyePtr, VB->Count, 2 ); input->stride = 4 * sizeof(GLfloat); input->count = VB->EyePtr->count; coord = VB->EyePtr->start; for (i = 0 ; i < VB->EyePtr->count; i++) { input->data[i][0] = fabsf(coord[2]); STRIDE_F(coord, VB->EyePtr->stride); } } } else { /* use glFogCoord() coordinates */ input = VB->AttribPtr[_TNL_ATTRIB_FOG]; /* source data */ /* input->count may be one if glFogCoord was only called once * before glBegin. But we need to compute fog for all vertices. */ input->count = VB->AttribPtr[_TNL_ATTRIB_POS]->count; VB->AttribPtr[_TNL_ATTRIB_FOG] = &store->fogcoord; /* dest data */ } if (tnl->_DoVertexFog) { /* compute blend factors from fog coordinates */ compute_fog_blend_factors( ctx, VB->AttribPtr[_TNL_ATTRIB_FOG], input ); } else { /* results = incoming fog coords (compute fog per-fragment later) */ VB->AttribPtr[_TNL_ATTRIB_FOG] = input; } return GL_TRUE; } /* Called the first time stage->run() is invoked. */ static GLboolean alloc_fog_data(struct gl_context *ctx, struct tnl_pipeline_stage *stage) { TNLcontext *tnl = TNL_CONTEXT(ctx); struct fog_stage_data *store; stage->privatePtr = malloc(sizeof(*store)); store = FOG_STAGE_DATA(stage); if (!store) return GL_FALSE; _mesa_vector4f_alloc( &store->fogcoord, 0, tnl->vb.Size, 32 ); if (!inited) init_static_data(); return GL_TRUE; } static void free_fog_data(struct tnl_pipeline_stage *stage) { struct fog_stage_data *store = FOG_STAGE_DATA(stage); if (store) { _mesa_vector4f_free( &store->fogcoord ); free( store ); stage->privatePtr = NULL; } } const struct tnl_pipeline_stage _tnl_fog_coordinate_stage = { "build fog coordinates", /* name */ NULL, /* private_data */ alloc_fog_data, /* dtr */ free_fog_data, /* dtr */ NULL, /* check */ run_fog_stage /* run -- initially set to init. */ };