#include "glheader.h"
#include "colormac.h"
#include "context.h"
#include "macros.h"
#include "mmath.h"
#include "s_context.h"
#include "s_fog.h"
#include "s_span.h"
GLfloat
_mesa_z_to_fogfactor(GLcontext *ctx, GLfloat z)
{
GLfloat d, f;
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);
f = (ctx->Fog.End - z) * d;
return CLAMP(f, 0.0F, 1.0F);
case GL_EXP:
d = ctx->Fog.Density;
f = (GLfloat) exp(-d * z);
return f;
case GL_EXP2:
d = ctx->Fog.Density;
f = (GLfloat) exp(-(d * d * z * z));
return f;
default:
_mesa_problem(ctx, "Bad fog mode in _mesa_z_to_fogfactor");
return 0.0;
}
}
static void
compute_fog_factors_from_z( const GLcontext *ctx,
GLuint n,
const GLdepth z[],
GLfloat fogFact[] )
{
const GLfloat *proj = ctx->ProjectionMatrixStack.Top->m;
const GLboolean ortho = (proj[15] != 0.0F);
const GLfloat p10 = proj[10];
const GLfloat p14 = proj[14];
const GLfloat tz = ctx->Viewport._WindowMap.m[MAT_TZ];
GLfloat szInv;
GLuint i;
if (ctx->Viewport._WindowMap.m[MAT_SZ] == 0.0)
szInv = 1.0F;
else
szInv = 1.0F / ctx->Viewport._WindowMap.m[MAT_SZ];
switch (ctx->Fog.Mode) {
case GL_LINEAR:
{
GLfloat fogEnd = ctx->Fog.End;
GLfloat fogScale;
if (ctx->Fog.Start == ctx->Fog.End)
fogScale = 1.0;
else
fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
if (ortho) {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = (ndcz - p14) / p10;
GLfloat f;
if (eyez < 0.0)
eyez = -eyez;
f = (fogEnd - eyez) * fogScale;
fogFact[i] = CLAMP(f, 0.0F, 1.0F);
}
}
else {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = p14 / (ndcz + p10);
GLfloat f;
if (eyez < 0.0)
eyez = -eyez;
f = (fogEnd - eyez) * fogScale;
fogFact[i] = CLAMP(f, 0.0F, 1.0F);
}
}
}
break;
case GL_EXP:
if (ortho) {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = (ndcz - p14) / p10;
if (eyez < 0.0)
eyez = -eyez;
fogFact[i] = (GLfloat) exp( -ctx->Fog.Density * eyez );
}
}
else {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = p14 / (ndcz + p10);
if (eyez < 0.0)
eyez = -eyez;
fogFact[i] = (GLfloat) exp( -ctx->Fog.Density * eyez );
}
}
break;
case GL_EXP2:
{
GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
if (ortho) {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = (ndcz - p14) / p10;
GLfloat tmp = negDensitySquared * eyez * eyez;
#if defined(__alpha__) || defined(__alpha)
if (tmp < FLT_MIN_10_EXP)
tmp = FLT_MIN_10_EXP;
#endif
fogFact[i] = (GLfloat) exp( tmp );
}
}
else {
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = p14 / (ndcz + p10);
GLfloat tmp = negDensitySquared * eyez * eyez;
#if defined(__alpha__) || defined(__alpha)
if (tmp < FLT_MIN_10_EXP)
tmp = FLT_MIN_10_EXP;
#endif
fogFact[i] = (GLfloat) exp( tmp );
}
}
}
break;
default:
_mesa_problem(ctx, "Bad fog mode in compute_fog_factors_from_z");
return;
}
}
void
_mesa_fog_rgba_span( const GLcontext *ctx, struct sw_span *span )
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLuint n = span->end;
GLchan (*rgba)[4] = (GLchan (*)[4]) span->array->rgba;
GLchan rFog, gFog, bFog;
ASSERT(ctx->Fog.Enabled);
ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG);
ASSERT(span->arrayMask & SPAN_RGBA);
UNCLAMPED_FLOAT_TO_CHAN(rFog, ctx->Fog.Color[RCOMP]);
UNCLAMPED_FLOAT_TO_CHAN(gFog, ctx->Fog.Color[GCOMP]);
UNCLAMPED_FLOAT_TO_CHAN(bFog, ctx->Fog.Color[BCOMP]);
if (swrast->_PreferPixelFog) {
if ((span->interpMask & SPAN_Z) && (span->arrayMask & SPAN_Z) == 0)
_mesa_span_interpolate_z(ctx, span);
compute_fog_factors_from_z(ctx, n, span->array->z, span->array->fog);
span->arrayMask |= SPAN_FOG;
}
if (span->arrayMask & SPAN_FOG) {
GLuint i;
for (i = 0; i < n; i++) {
const GLfloat fog = span->array->fog[i];
const GLfloat oneMinusFog = 1.0F - fog;
rgba[i][RCOMP] = (GLchan) (fog * rgba[i][RCOMP] + oneMinusFog * rFog);
rgba[i][GCOMP] = (GLchan) (fog * rgba[i][GCOMP] + oneMinusFog * gFog);
rgba[i][BCOMP] = (GLchan) (fog * rgba[i][BCOMP] + oneMinusFog * bFog);
}
}
else {
GLfloat fog = span->fog, dFog = span->fogStep;
GLuint i;
for (i = 0; i < n; i++) {
const GLfloat oneMinusFog = 1.0F - fog;
rgba[i][RCOMP] = (GLchan) (fog * rgba[i][RCOMP] + oneMinusFog * rFog);
rgba[i][GCOMP] = (GLchan) (fog * rgba[i][GCOMP] + oneMinusFog * gFog);
rgba[i][BCOMP] = (GLchan) (fog * rgba[i][BCOMP] + oneMinusFog * bFog);
fog += dFog;
}
}
}
void
_mesa_fog_ci_span( const GLcontext *ctx, struct sw_span *span )
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLuint n = span->end;
GLuint *index = span->array->index;
ASSERT(ctx->Fog.Enabled);
ASSERT(span->arrayMask & SPAN_INDEX);
ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG);
if (swrast->_PreferPixelFog) {
if ((span->interpMask & SPAN_Z) && (span->arrayMask & SPAN_Z) == 0)
_mesa_span_interpolate_z(ctx, span);
compute_fog_factors_from_z(ctx, n, span->array->z, span->array->fog);
span->arrayMask |= SPAN_FOG;
}
if (span->arrayMask & SPAN_FOG) {
const GLuint idx = (GLuint) ctx->Fog.Index;
GLuint i;
for (i = 0; i < n; i++) {
const GLfloat f = CLAMP(span->array->fog[i], 0.0F, 1.0F);
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * idx);
}
}
else {
GLfloat fog = span->fog, dFog = span->fogStep;
const GLuint idx = (GLuint) ctx->Fog.Index;
GLuint i;
for (i = 0; i < n; i++) {
const GLfloat f = CLAMP(fog, 0.0F, 1.0F);
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * idx);
fog += dFog;
}
}
}