| /* |
| * 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 <keithw@vmware.com> |
| */ |
| |
| |
| #include "c99_math.h" |
| #include "main/errors.h" |
| #include "main/glheader.h" |
| #include "main/macros.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. */ |
| }; |