/**
* Apply fog to a span of RGBA pixels.
* The fog value are either in the span->array->fog array or interpolated from
* the fog/fogStep values.
* They fog values are either fog coordinates (Z) or fog blend factors.
* _PreferPixelFog should be in sync with that state!
*/
void
_swrast_fog_rgba_span( const GLcontext *ctx, SWspan *span )
{
const SWcontext *swrast = CONST_SWRAST_CONTEXT(ctx);
GLfloat rFog, gFog, bFog;
ASSERT(swrast->_FogEnabled);
ASSERT(span->arrayMask & SPAN_RGBA);
/* compute (scaled) fog color */
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
rFog = ctx->Fog.Color[RCOMP] * 255.0F;
gFog = ctx->Fog.Color[GCOMP] * 255.0F;
bFog = ctx->Fog.Color[BCOMP] * 255.0F;
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
rFog = ctx->Fog.Color[RCOMP] * 65535.0F;
gFog = ctx->Fog.Color[GCOMP] * 65535.0F;
bFog = ctx->Fog.Color[BCOMP] * 65535.0F;
}
else {
rFog = ctx->Fog.Color[RCOMP];
gFog = ctx->Fog.Color[GCOMP];
bFog = ctx->Fog.Color[BCOMP];
}
if (swrast->_PreferPixelFog) {
/* The span's fog values are fog coordinates, now compute blend factors
* and blend the fragment colors with the fog color.
*/
switch (swrast->_FogMode) {
case GL_LINEAR:
{
const GLfloat fogEnd = ctx->Fog.End;
const GLfloat fogScale = (ctx->Fog.Start == ctx->Fog.End)
? 1.0F : 1.0F / (ctx->Fog.End - ctx->Fog.Start);
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->rgba8;
FOG_LOOP(GLubyte, LINEAR_FOG);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->rgba16;
FOG_LOOP(GLushort, LINEAR_FOG);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, LINEAR_FOG);
}
}
break;
case GL_EXP:
{
const GLfloat density = -ctx->Fog.Density;
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->rgba8;
FOG_LOOP(GLubyte, EXP_FOG);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->rgba16;
FOG_LOOP(GLushort, EXP_FOG);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, EXP_FOG);
}
}
break;
case GL_EXP2:
{
const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->rgba8;
FOG_LOOP(GLubyte, EXP2_FOG);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->rgba16;
FOG_LOOP(GLushort, EXP2_FOG);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, EXP2_FOG);
}
}
break;
default:
_mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span");
return;
}
}
else {
/* The span's fog start/step/array values are blend factors in [0,1].
* They were previously computed per-vertex.
*/
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->rgba8;
FOG_LOOP(GLubyte, BLEND_FOG);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->rgba16;
FOG_LOOP(GLushort, BLEND_FOG);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, BLEND_FOG);
}
}
}
/**
* Apply fog to a span of RGBA pixels.
* The fog value are either in the span->array->fog array or interpolated from
* the fog/fogStep values.
* They fog values are either fog coordinates (Z) or fog blend factors.
* _PreferPixelFog should be in sync with that state!
*/
void
_swrast_fog_rgba_span( const GLcontext *ctx, SWspan *span )
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
GLfloat rFog, gFog, bFog;
const GLuint haveW = (span->interpMask & SPAN_W);
ASSERT(swrast->_FogEnabled);
ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG);
ASSERT(span->arrayMask & SPAN_RGBA);
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
rFog = ctx->Fog.Color[RCOMP] * 255.0;
gFog = ctx->Fog.Color[GCOMP] * 255.0;
bFog = ctx->Fog.Color[BCOMP] * 255.0;
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
rFog = ctx->Fog.Color[RCOMP] * 65535.0;
gFog = ctx->Fog.Color[GCOMP] * 65535.0;
bFog = ctx->Fog.Color[BCOMP] * 65535.0;
}
else {
rFog = ctx->Fog.Color[RCOMP];
gFog = ctx->Fog.Color[GCOMP];
bFog = ctx->Fog.Color[BCOMP];
}
/* NOTE: if haveW is true, that means the fog start/step values are
* perspective-corrected and we have to divide each fog coord by W.
*/
/* we need to compute fog blend factors */
if (swrast->_PreferPixelFog) {
/* The span's fog values are fog coordinates, now compute blend factors
* and blend the fragment colors with the fog color.
*/
const GLfloat fogEnd = ctx->Fog.End;
const GLfloat fogScale = (ctx->Fog.Start == ctx->Fog.End)
? 1.0F : 1.0F / (ctx->Fog.End - ctx->Fog.Start);
const GLfloat density = -ctx->Fog.Density;
const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
switch (swrast->_FogMode) {
case GL_LINEAR:
#define COMPUTE_F f = (fogEnd - FABSF(fogCoord) / w) * fogScale;
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->color.sz1.rgba;
FOG_LOOP(GLubyte, COMPUTE_F);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->color.sz2.rgba;
FOG_LOOP(GLushort, COMPUTE_F);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, COMPUTE_F);
}
#undef COMPUTE_F
break;
case GL_EXP:
#define COMPUTE_F f = EXPF(density * FABSF(fogCoord) / w);
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->color.sz1.rgba;
FOG_LOOP(GLubyte, COMPUTE_F);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->color.sz2.rgba;
FOG_LOOP(GLushort, COMPUTE_F);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, COMPUTE_F);
}
#undef COMPUTE_F
break;
case GL_EXP2:
#define COMPUTE_F const GLfloat coord = fogCoord / w; \
GLfloat tmp = negDensitySquared * coord * coord; \
if (tmp < FLT_MIN_10_EXP) \
tmp = FLT_MIN_10_EXP; \
f = EXPF(tmp);
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->color.sz1.rgba;
FOG_LOOP(GLubyte, COMPUTE_F);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->color.sz2.rgba;
FOG_LOOP(GLushort, COMPUTE_F);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, COMPUTE_F);
}
#undef COMPUTE_F
break;
default:
_mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span");
return;
}
}
else if (span->arrayMask & SPAN_FOG) {
/* The span's fog array values are blend factors.
* They were previously computed per-vertex.
*/
GLuint i;
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->color.sz1.rgba;
for (i = 0; i < span->end; i++) {
const GLfloat f = span->array->attribs[FRAG_ATTRIB_FOGC][i][0];
const GLfloat oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLubyte) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLubyte) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLubyte) (f * rgba[i][BCOMP] + oneMinusF * bFog);
}
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->color.sz2.rgba;
for (i = 0; i < span->end; i++) {
const GLfloat f = span->array->attribs[FRAG_ATTRIB_FOGC][i][0];
const GLfloat oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLushort) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLushort) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLushort) (f * rgba[i][BCOMP] + oneMinusF * bFog);
}
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
for (i = 0; i < span->end; i++) {
const GLfloat f = span->array->attribs[FRAG_ATTRIB_FOGC][i][0];
const GLfloat oneMinusF = 1.0F - f;
rgba[i][RCOMP] = f * rgba[i][RCOMP] + oneMinusF * rFog;
rgba[i][GCOMP] = f * rgba[i][GCOMP] + oneMinusF * gFog;
rgba[i][BCOMP] = f * rgba[i][BCOMP] + oneMinusF * bFog;
}
}
}
else {
/* The span's fog start/step values are blend factors.
* They were previously computed per-vertex.
*/
#define COMPUTE_F f = fogCoord / w;
if (span->array->ChanType == GL_UNSIGNED_BYTE) {
GLubyte (*rgba)[4] = span->array->color.sz1.rgba;
FOG_LOOP(GLubyte, COMPUTE_F);
}
else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
GLushort (*rgba)[4] = span->array->color.sz2.rgba;
FOG_LOOP(GLushort, COMPUTE_F);
}
else {
GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
ASSERT(span->array->ChanType == GL_FLOAT);
FOG_LOOP(GLfloat, COMPUTE_F);
}
#undef COMPUTE_F
}
}
