/**
* Do texture application for:
* GL_EXT_texture_env_combine
* GL_ARB_texture_env_combine
* GL_EXT_texture_env_dot3
* GL_ARB_texture_env_dot3
* GL_ATI_texture_env_combine3
* GL_NV_texture_env_combine4
* conventional GL texture env modes
*
* \param ctx rendering context
* \param unit the texture combiner unit
* \param primary_rgba incoming fragment color array
* \param texelBuffer pointer to texel colors for all texture units
*
* \param span two fields are used in this function:
* span->end: number of fragments to process
* span->array->rgba: incoming/result fragment colors
*/
static void
texture_combine( struct gl_context *ctx, GLuint unit,
const float4_array primary_rgba,
const GLfloat *texelBuffer,
SWspan *span )
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
const struct gl_texture_unit *textureUnit = &(ctx->Texture.Unit[unit]);
const struct gl_tex_env_combine_state *combine = textureUnit->_CurrentCombine;
float4_array argRGB[MAX_COMBINER_TERMS];
float4_array argA[MAX_COMBINER_TERMS];
const GLfloat scaleRGB = (GLfloat) (1 << combine->ScaleShiftRGB);
const GLfloat scaleA = (GLfloat) (1 << combine->ScaleShiftA);
const GLuint numArgsRGB = combine->_NumArgsRGB;
const GLuint numArgsA = combine->_NumArgsA;
float4_array ccolor[4], rgba;
GLuint i, term;
GLuint n = span->end;
GLchan (*rgbaChan)[4] = span->array->rgba;
/* alloc temp pixel buffers */
rgba = malloc(4 * n * sizeof(GLfloat));
if (!rgba) {
_mesa_error(ctx, GL_OUT_OF_MEMORY, "texture_combine");
return;
}
for (i = 0; i < numArgsRGB || i < numArgsA; i++) {
ccolor[i] = malloc(4 * n * sizeof(GLfloat));
if (!ccolor[i]) {
while (i) {
free(ccolor[i]);
i--;
}
_mesa_error(ctx, GL_OUT_OF_MEMORY, "texture_combine");
free(rgba);
return;
}
}
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = CHAN_TO_FLOAT(rgbaChan[i][RCOMP]);
rgba[i][GCOMP] = CHAN_TO_FLOAT(rgbaChan[i][GCOMP]);
rgba[i][BCOMP] = CHAN_TO_FLOAT(rgbaChan[i][BCOMP]);
rgba[i][ACOMP] = CHAN_TO_FLOAT(rgbaChan[i][ACOMP]);
}
/*
printf("modeRGB 0x%x modeA 0x%x srcRGB1 0x%x srcA1 0x%x srcRGB2 0x%x srcA2 0x%x\n",
combine->ModeRGB,
combine->ModeA,
combine->SourceRGB[0],
combine->SourceA[0],
combine->SourceRGB[1],
combine->SourceA[1]);
*/
/*
* Do operand setup for up to 4 operands. Loop over the terms.
*/
for (term = 0; term < numArgsRGB; term++) {
const GLenum srcRGB = combine->SourceRGB[term];
const GLenum operandRGB = combine->OperandRGB[term];
switch (srcRGB) {
case GL_TEXTURE:
argRGB[term] = get_texel_array(swrast, unit);
break;
case GL_PRIMARY_COLOR:
argRGB[term] = primary_rgba;
break;
case GL_PREVIOUS:
argRGB[term] = rgba;
break;
case GL_CONSTANT:
{
float4_array c = ccolor[term];
GLfloat red = textureUnit->EnvColor[0];
GLfloat green = textureUnit->EnvColor[1];
GLfloat blue = textureUnit->EnvColor[2];
GLfloat alpha = textureUnit->EnvColor[3];
for (i = 0; i < n; i++) {
ASSIGN_4V(c[i], red, green, blue, alpha);
}
argRGB[term] = ccolor[term];
}
break;
/* GL_ATI_texture_env_combine3 allows GL_ZERO & GL_ONE as sources.
*/
case GL_ZERO:
{
float4_array c = ccolor[term];
for (i = 0; i < n; i++) {
ASSIGN_4V(c[i], 0.0F, 0.0F, 0.0F, 0.0F);
}
argRGB[term] = ccolor[term];
}
break;
case GL_ONE:
{
float4_array c = ccolor[term];
for (i = 0; i < n; i++) {
ASSIGN_4V(c[i], 1.0F, 1.0F, 1.0F, 1.0F);
}
argRGB[term] = ccolor[term];
}
break;
default:
/* ARB_texture_env_crossbar source */
{
const GLuint srcUnit = srcRGB - GL_TEXTURE0;
ASSERT(srcUnit < ctx->Const.MaxTextureUnits);
if (!ctx->Texture.Unit[srcUnit]._ReallyEnabled)
goto end;
argRGB[term] = get_texel_array(swrast, srcUnit);
}
}
if (operandRGB != GL_SRC_COLOR) {
float4_array src = argRGB[term];
float4_array dst = ccolor[term];
/* point to new arg[term] storage */
argRGB[term] = ccolor[term];
switch (operandRGB) {
case GL_ONE_MINUS_SRC_COLOR:
for (i = 0; i < n; i++) {
dst[i][RCOMP] = 1.0F - src[i][RCOMP];
dst[i][GCOMP] = 1.0F - src[i][GCOMP];
dst[i][BCOMP] = 1.0F - src[i][BCOMP];
}
break;
case GL_SRC_ALPHA:
for (i = 0; i < n; i++) {
dst[i][RCOMP] =
dst[i][GCOMP] =
dst[i][BCOMP] = src[i][ACOMP];
}
break;
case GL_ONE_MINUS_SRC_ALPHA:
for (i = 0; i < n; i++) {
dst[i][RCOMP] =
dst[i][GCOMP] =
dst[i][BCOMP] = 1.0F - src[i][ACOMP];
}
break;
default:
_mesa_problem(ctx, "Bad operandRGB");
}
}
}
/*
* Set up the argA[term] pointers
*/
for (term = 0; term < numArgsA; term++) {
const GLenum srcA = combine->SourceA[term];
const GLenum operandA = combine->OperandA[term];
switch (srcA) {
case GL_TEXTURE:
argA[term] = get_texel_array(swrast, unit);
break;
case GL_PRIMARY_COLOR:
argA[term] = primary_rgba;
break;
case GL_PREVIOUS:
argA[term] = rgba;
break;
case GL_CONSTANT:
{
float4_array c = ccolor[term];
GLfloat alpha = textureUnit->EnvColor[3];
for (i = 0; i < n; i++)
c[i][ACOMP] = alpha;
argA[term] = ccolor[term];
}
break;
/* GL_ATI_texture_env_combine3 allows GL_ZERO & GL_ONE as sources.
*/
case GL_ZERO:
{
float4_array c = ccolor[term];
for (i = 0; i < n; i++)
c[i][ACOMP] = 0.0F;
argA[term] = ccolor[term];
}
break;
case GL_ONE:
{
float4_array c = ccolor[term];
for (i = 0; i < n; i++)
c[i][ACOMP] = 1.0F;
argA[term] = ccolor[term];
}
break;
default:
/* ARB_texture_env_crossbar source */
{
const GLuint srcUnit = srcA - GL_TEXTURE0;
ASSERT(srcUnit < ctx->Const.MaxTextureUnits);
if (!ctx->Texture.Unit[srcUnit]._ReallyEnabled)
goto end;
argA[term] = get_texel_array(swrast, srcUnit);
}
}
if (operandA == GL_ONE_MINUS_SRC_ALPHA) {
float4_array src = argA[term];
float4_array dst = ccolor[term];
argA[term] = ccolor[term];
for (i = 0; i < n; i++) {
dst[i][ACOMP] = 1.0F - src[i][ACOMP];
}
}
}
/* RGB channel combine */
{
float4_array arg0 = argRGB[0];
float4_array arg1 = argRGB[1];
float4_array arg2 = argRGB[2];
float4_array arg3 = argRGB[3];
switch (combine->ModeRGB) {
case GL_REPLACE:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = arg0[i][RCOMP] * scaleRGB;
rgba[i][GCOMP] = arg0[i][GCOMP] * scaleRGB;
rgba[i][BCOMP] = arg0[i][BCOMP] * scaleRGB;
}
break;
case GL_MODULATE:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = arg0[i][RCOMP] * arg1[i][RCOMP] * scaleRGB;
rgba[i][GCOMP] = arg0[i][GCOMP] * arg1[i][GCOMP] * scaleRGB;
rgba[i][BCOMP] = arg0[i][BCOMP] * arg1[i][BCOMP] * scaleRGB;
}
break;
case GL_ADD:
if (textureUnit->EnvMode == GL_COMBINE4_NV) {
/* (a * b) + (c * d) */
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] * arg1[i][RCOMP] +
arg2[i][RCOMP] * arg3[i][RCOMP]) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] * arg1[i][GCOMP] +
arg2[i][GCOMP] * arg3[i][GCOMP]) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] * arg1[i][BCOMP] +
arg2[i][BCOMP] * arg3[i][BCOMP]) * scaleRGB;
}
}
else {
/* 2-term addition */
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] + arg1[i][RCOMP]) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] + arg1[i][GCOMP]) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] + arg1[i][BCOMP]) * scaleRGB;
}
}
break;
case GL_ADD_SIGNED:
if (textureUnit->EnvMode == GL_COMBINE4_NV) {
/* (a * b) + (c * d) - 0.5 */
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] * arg1[i][RCOMP] +
arg2[i][RCOMP] * arg3[i][RCOMP] - 0.5F) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] * arg1[i][GCOMP] +
arg2[i][GCOMP] * arg3[i][GCOMP] - 0.5F) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] * arg1[i][BCOMP] +
arg2[i][BCOMP] * arg3[i][BCOMP] - 0.5F) * scaleRGB;
}
}
else {
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] + arg1[i][RCOMP] - 0.5F) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] + arg1[i][GCOMP] - 0.5F) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] + arg1[i][BCOMP] - 0.5F) * scaleRGB;
}
}
break;
case GL_INTERPOLATE:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] * arg2[i][RCOMP] +
arg1[i][RCOMP] * (1.0F - arg2[i][RCOMP])) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] * arg2[i][GCOMP] +
arg1[i][GCOMP] * (1.0F - arg2[i][GCOMP])) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] * arg2[i][BCOMP] +
arg1[i][BCOMP] * (1.0F - arg2[i][BCOMP])) * scaleRGB;
}
break;
case GL_SUBTRACT:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = (arg0[i][RCOMP] - arg1[i][RCOMP]) * scaleRGB;
rgba[i][GCOMP] = (arg0[i][GCOMP] - arg1[i][GCOMP]) * scaleRGB;
rgba[i][BCOMP] = (arg0[i][BCOMP] - arg1[i][BCOMP]) * scaleRGB;
}
break;
case GL_DOT3_RGB_EXT:
case GL_DOT3_RGBA_EXT:
/* Do not scale the result by 1 2 or 4 */
for (i = 0; i < n; i++) {
GLfloat dot = ((arg0[i][RCOMP] - 0.5F) * (arg1[i][RCOMP] - 0.5F) +
(arg0[i][GCOMP] - 0.5F) * (arg1[i][GCOMP] - 0.5F) +
(arg0[i][BCOMP] - 0.5F) * (arg1[i][BCOMP] - 0.5F))
* 4.0F;
dot = CLAMP(dot, 0.0F, 1.0F);
rgba[i][RCOMP] = rgba[i][GCOMP] = rgba[i][BCOMP] = dot;
}
break;
case GL_DOT3_RGB:
case GL_DOT3_RGBA:
/* DO scale the result by 1 2 or 4 */
for (i = 0; i < n; i++) {
GLfloat dot = ((arg0[i][RCOMP] - 0.5F) * (arg1[i][RCOMP] - 0.5F) +
(arg0[i][GCOMP] - 0.5F) * (arg1[i][GCOMP] - 0.5F) +
(arg0[i][BCOMP] - 0.5F) * (arg1[i][BCOMP] - 0.5F))
* 4.0F * scaleRGB;
dot = CLAMP(dot, 0.0F, 1.0F);
rgba[i][RCOMP] = rgba[i][GCOMP] = rgba[i][BCOMP] = dot;
}
break;
case GL_MODULATE_ADD_ATI:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = ((arg0[i][RCOMP] * arg2[i][RCOMP]) +
arg1[i][RCOMP]) * scaleRGB;
rgba[i][GCOMP] = ((arg0[i][GCOMP] * arg2[i][GCOMP]) +
arg1[i][GCOMP]) * scaleRGB;
rgba[i][BCOMP] = ((arg0[i][BCOMP] * arg2[i][BCOMP]) +
arg1[i][BCOMP]) * scaleRGB;
}
break;
case GL_MODULATE_SIGNED_ADD_ATI:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = ((arg0[i][RCOMP] * arg2[i][RCOMP]) +
arg1[i][RCOMP] - 0.5F) * scaleRGB;
rgba[i][GCOMP] = ((arg0[i][GCOMP] * arg2[i][GCOMP]) +
arg1[i][GCOMP] - 0.5F) * scaleRGB;
rgba[i][BCOMP] = ((arg0[i][BCOMP] * arg2[i][BCOMP]) +
arg1[i][BCOMP] - 0.5F) * scaleRGB;
}
break;
case GL_MODULATE_SUBTRACT_ATI:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = ((arg0[i][RCOMP] * arg2[i][RCOMP]) -
arg1[i][RCOMP]) * scaleRGB;
rgba[i][GCOMP] = ((arg0[i][GCOMP] * arg2[i][GCOMP]) -
arg1[i][GCOMP]) * scaleRGB;
rgba[i][BCOMP] = ((arg0[i][BCOMP] * arg2[i][BCOMP]) -
arg1[i][BCOMP]) * scaleRGB;
}
break;
case GL_BUMP_ENVMAP_ATI:
/* this produces a fixed rgba color, and the coord calc is done elsewhere */
for (i = 0; i < n; i++) {
/* rgba result is 0,0,0,1 */
rgba[i][RCOMP] = 0.0;
rgba[i][GCOMP] = 0.0;
rgba[i][BCOMP] = 0.0;
rgba[i][ACOMP] = 1.0;
}
goto end; /* no alpha processing */
default:
_mesa_problem(ctx, "invalid combine mode");
}
}
/* Alpha channel combine */
{
float4_array arg0 = argA[0];
float4_array arg1 = argA[1];
float4_array arg2 = argA[2];
float4_array arg3 = argA[3];
switch (combine->ModeA) {
case GL_REPLACE:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = arg0[i][ACOMP] * scaleA;
}
break;
case GL_MODULATE:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = arg0[i][ACOMP] * arg1[i][ACOMP] * scaleA;
}
break;
case GL_ADD:
if (textureUnit->EnvMode == GL_COMBINE4_NV) {
/* (a * b) + (c * d) */
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] * arg1[i][ACOMP] +
arg2[i][ACOMP] * arg3[i][ACOMP]) * scaleA;
}
}
else {
/* two-term add */
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] + arg1[i][ACOMP]) * scaleA;
}
}
break;
case GL_ADD_SIGNED:
if (textureUnit->EnvMode == GL_COMBINE4_NV) {
/* (a * b) + (c * d) - 0.5 */
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] * arg1[i][ACOMP] +
arg2[i][ACOMP] * arg3[i][ACOMP] -
0.5F) * scaleA;
}
}
else {
/* a + b - 0.5 */
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] + arg1[i][ACOMP] - 0.5F) * scaleA;
}
}
break;
case GL_INTERPOLATE:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] * arg2[i][ACOMP] +
arg1[i][ACOMP] * (1.0F - arg2[i][ACOMP]))
* scaleA;
}
break;
case GL_SUBTRACT:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = (arg0[i][ACOMP] - arg1[i][ACOMP]) * scaleA;
}
break;
case GL_MODULATE_ADD_ATI:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = ((arg0[i][ACOMP] * arg2[i][ACOMP])
+ arg1[i][ACOMP]) * scaleA;
}
break;
case GL_MODULATE_SIGNED_ADD_ATI:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = ((arg0[i][ACOMP] * arg2[i][ACOMP]) +
arg1[i][ACOMP] - 0.5F) * scaleA;
}
break;
case GL_MODULATE_SUBTRACT_ATI:
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = ((arg0[i][ACOMP] * arg2[i][ACOMP])
- arg1[i][ACOMP]) * scaleA;
}
break;
default:
_mesa_problem(ctx, "invalid combine mode");
}
}
/* Fix the alpha component for GL_DOT3_RGBA_EXT/ARB combining.
* This is kind of a kludge. It would have been better if the spec
* were written such that the GL_COMBINE_ALPHA value could be set to
* GL_DOT3.
*/
if (combine->ModeRGB == GL_DOT3_RGBA_EXT ||
combine->ModeRGB == GL_DOT3_RGBA) {
for (i = 0; i < n; i++) {
rgba[i][ACOMP] = rgba[i][RCOMP];
}
}
for (i = 0; i < n; i++) {
UNCLAMPED_FLOAT_TO_CHAN(rgbaChan[i][RCOMP], rgba[i][RCOMP]);
UNCLAMPED_FLOAT_TO_CHAN(rgbaChan[i][GCOMP], rgba[i][GCOMP]);
UNCLAMPED_FLOAT_TO_CHAN(rgbaChan[i][BCOMP], rgba[i][BCOMP]);
UNCLAMPED_FLOAT_TO_CHAN(rgbaChan[i][ACOMP], rgba[i][ACOMP]);
}
/* The span->array->rgba values are of CHAN type so set
* span->array->ChanType field accordingly.
*/
span->array->ChanType = CHAN_TYPE;
end:
for (i = 0; i < numArgsRGB || i < numArgsA; i++) {
free(ccolor[i]);
}
free(rgba);
}
/**
* 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, struct sw_span *span )
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLchan rFog = swrast->_FogColor[RCOMP];
const GLchan gFog = swrast->_FogColor[GCOMP];
const GLchan bFog = swrast->_FogColor[BCOMP];
const GLuint haveW = (span->interpMask & SPAN_W);
GLchan (*rgba)[4] = (GLchan (*)[4]) span->array->rgba;
ASSERT(swrast->_FogEnabled);
ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG);
ASSERT(span->arrayMask & SPAN_RGBA);
/* 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.
*/
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);
const GLfloat fogStep = span->fogStep;
GLfloat fogCoord = span->fog;
const GLfloat wStep = haveW ? span->dwdx : 0.0F;
GLfloat w = haveW ? span->w : 1.0F;
GLuint i;
for (i = 0; i < span->end; i++) {
GLfloat f, oneMinusF;
f = (fogEnd - fogCoord / w) * fogScale;
f = CLAMP(f, 0.0F, 1.0F);
oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLchan) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLchan) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLchan) (f * rgba[i][BCOMP] + oneMinusF * bFog);
fogCoord += fogStep;
w += wStep;
}
}
break;
case GL_EXP:
{
const GLfloat density = -ctx->Fog.Density;
const GLfloat fogStep = span->fogStep;
GLfloat fogCoord = span->fog;
const GLfloat wStep = haveW ? span->dwdx : 0.0F;
GLfloat w = haveW ? span->w : 1.0F;
GLuint i;
for (i = 0; i < span->end; i++) {
GLfloat f, oneMinusF;
f = (GLfloat) exp(density * fogCoord / w);
f = CLAMP(f, 0.0F, 1.0F);
oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLchan) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLchan) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLchan) (f * rgba[i][BCOMP] + oneMinusF * bFog);
fogCoord += fogStep;
w += wStep;
}
}
break;
case GL_EXP2:
{
const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
const GLfloat fogStep = span->fogStep;
GLfloat fogCoord = span->fog;
const GLfloat wStep = haveW ? span->dwdx : 0.0F;
GLfloat w = haveW ? span->w : 1.0F;
GLuint i;
for (i = 0; i < span->end; i++) {
const GLfloat coord = fogCoord / w;
GLfloat tmp = negDensitySquared * coord * coord;
GLfloat f, oneMinusF;
#if defined(__alpha__) || defined(__alpha)
/* XXX this underflow check may be needed for other systems*/
if (tmp < FLT_MIN_10_EXP)
tmp = FLT_MIN_10_EXP;
#endif
f = (GLfloat) exp(tmp);
f = CLAMP(f, 0.0F, 1.0F);
oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLchan) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLchan) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLchan) (f * rgba[i][BCOMP] + oneMinusF * bFog);
fogCoord += fogStep;
w += wStep;
}
}
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;
for (i = 0; i < span->end; i++) {
const GLfloat f = span->array->fog[i];
const GLfloat oneMinusF = 1.0F - f;
rgba[i][RCOMP] = (GLchan) (f * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLchan) (f * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLchan) (f * rgba[i][BCOMP] + oneMinusF * bFog);
}
}
else {
/* The span's fog start/step values are blend factors.
* They were previously computed per-vertex.
*/
const GLfloat fogStep = span->fogStep;
GLfloat fog = span->fog;
const GLfloat wStep = haveW ? span->dwdx : 0.0F;
GLfloat w = haveW ? span->w : 1.0F;
GLuint i;
ASSERT(span->interpMask & SPAN_FOG);
for (i = 0; i < span->end; i++) {
const GLfloat fact = fog / w;
const GLfloat oneMinusF = 1.0F - fact;
rgba[i][RCOMP] = (GLchan) (fact * rgba[i][RCOMP] + oneMinusF * rFog);
rgba[i][GCOMP] = (GLchan) (fact * rgba[i][GCOMP] + oneMinusF * gFog);
rgba[i][BCOMP] = (GLchan) (fact * rgba[i][BCOMP] + oneMinusF * bFog);
fog += fogStep;
w += wStep;
}
}
}
