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-rw-r--r--mesalib/src/mesa/tnl/t_vb_fog.c277
1 files changed, 277 insertions, 0 deletions
diff --git a/mesalib/src/mesa/tnl/t_vb_fog.c b/mesalib/src/mesa/tnl/t_vb_fog.c
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+++ b/mesalib/src/mesa/tnl/t_vb_fog.c
@@ -0,0 +1,277 @@
+/*
+ * Mesa 3-D graphics library
+ * Version: 6.5
+ *
+ * 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
+ * BRIAN PAUL 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 <keith@tungstengraphics.com>
+ */
+
+
+#include "main/glheader.h"
+#include "main/colormac.h"
+#include "main/context.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 (10.0)
+#define EXP_FOG_MAX .0006595
+#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 * (1.0/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(GLcontext *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(GLcontext *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->ObjPtr 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->ObjPtr->size]( (GLfloat *) input->data,
+ 4 * sizeof(GLfloat),
+ VB->ObjPtr, plane );
+
+ input->count = VB->ObjPtr->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->ObjPtr->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;
+ }
+
+ VB->FogCoordPtr = VB->AttribPtr[_TNL_ATTRIB_FOG];
+ return GL_TRUE;
+}
+
+
+
+/* Called the first time stage->run() is invoked.
+ */
+static GLboolean
+alloc_fog_data(GLcontext *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. */
+};
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