-/* $Id: s_fog.c,v 1.2 2000/11/05 18:24:40 keithw Exp $ */
+/* $Id: s_fog.c,v 1.9 2001/03/03 20:33:30 brianp Exp $ */
/*
* Mesa 3-D graphics library
#include "s_context.h"
#include "s_fog.h"
+#include "s_pb.h"
/*
const GLfixed fog[],
GLchan rgba[][4] )
{
- GLfixed rFog = ctx->Fog.Color[0] * CHAN_MAXF;
- GLfixed gFog = ctx->Fog.Color[1] * CHAN_MAXF;
- GLfixed bFog = ctx->Fog.Color[2] * CHAN_MAXF;
GLuint i;
+ GLchan rFog, gFog, bFog;
- for (i=0;i<n;i++) {
- GLfixed f = CLAMP(fog[i], 0, FIXED_ONE);
- GLfixed g = FIXED_ONE - f;
- rgba[i][0] = (f*rgba[i][0] + g*rFog) >> FIXED_SHIFT;
- rgba[i][1] = (f*rgba[i][1] + g*gFog) >> FIXED_SHIFT;
- rgba[i][2] = (f*rgba[i][2] + g*bFog) >> FIXED_SHIFT;
+ 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 CHAN_TYPE == GL_FLOAT
+ for (i = 0; i < n; i++) {
+ const GLfixed cf = CLAMP(fog[i], 0, FIXED_ONE);
+ const GLfloat f = FixedToFloat(cf);
+ const GLfloat g = 1.0F - f;
+ rgba[i][RCOMP] = f * rgba[i][RCOMP] + g * rFog;
+ rgba[i][GCOMP] = f * rgba[i][GCOMP] + g * gFog;
+ rgba[i][BCOMP] = f * rgba[i][BCOMP] + g * bFog;
+ }
+#else
+ for (i = 0; i < n; i++) {
+ const GLfixed f = CLAMP(fog[i], 0, FIXED_ONE);
+ const GLfixed g = FIXED_ONE - f;
+ rgba[i][0] = (f * rgba[i][0] + g * rFog) >> FIXED_SHIFT;
+ rgba[i][1] = (f * rgba[i][1] + g * gFog) >> FIXED_SHIFT;
+ rgba[i][2] = (f * rgba[i][2] + g * bFog) >> FIXED_SHIFT;
}
+#endif
}
-
/*
* Apply fog to an array of color index pixels.
* Input: n - number of pixels
GLuint i;
for (i=0;i<n;i++) {
- GLfixed f = FixedToFloat(CLAMP(fog[i], 0, FIXED_ONE));
+ GLfloat f = FixedToFloat(CLAMP(fog[i], 0, FIXED_ONE));
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * idx);
}
}
const GLdepth z[],
GLfixed fogcoord[] )
{
- GLfloat c = ctx->ProjectionMatrix.m[10];
- GLfloat d = ctx->ProjectionMatrix.m[14];
+ const GLboolean ortho = (ctx->ProjectionMatrix.m[15] != 0.0F);
+ const GLfloat p10 = ctx->ProjectionMatrix.m[10];
+ const GLfloat p14 = ctx->ProjectionMatrix.m[14];
+ const GLfloat tz = ctx->Viewport._WindowMap.m[MAT_TZ];
+ GLfloat szInv;
GLuint i;
- GLfloat tz = ctx->Viewport._WindowMap.m[MAT_TZ];
- GLfloat szInv = 1.0F / ctx->Viewport._WindowMap.m[MAT_SZ];
+ if (ctx->Viewport._WindowMap.m[MAT_SZ] == 0.0)
+ szInv = 1.0F;
+ else
+ szInv = 1.0F / ctx->Viewport._WindowMap.m[MAT_SZ];
+
+ /*
+ * Note: to compute eyeZ from the ndcZ we have to solve the following:
+ *
+ * p[10] * eyeZ + p[14] * eyeW
+ * ndcZ = ---------------------------
+ * p[11] * eyeZ + p[15] * eyeW
+ *
+ * Thus:
+ *
+ * p[14] * eyeW - p[15] * eyeW * ndcZ
+ * eyeZ = ----------------------------------
+ * p[11] * ndcZ - p[10]
+ *
+ * If we note:
+ * a) if using an orthographic projection, p[11] = 0 and p[15] = 1.
+ * b) if using a perspective projection, p[11] = -1 and p[15] = 0.
+ * c) we assume eyeW = 1 (not always true- glVertex4)
+ *
+ * Then we can simplify the calculation of eyeZ quite a bit. We do
+ * separate calculations for the orthographic and perspective cases below.
+ * Note that we drop a negative sign or two since they don't matter.
+ */
switch (ctx->Fog.Mode) {
case GL_LINEAR:
{
GLfloat fogEnd = ctx->Fog.End;
- GLfloat fogScale = (GLfloat) FIXED_ONE / (ctx->Fog.End -
- ctx->Fog.Start);
- for (i=0;i<n;i++) {
- GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
- GLfloat eyez = -d / (c+ndcz);
- if (eyez < 0.0) eyez = -eyez;
- fogcoord[i] = (GLint)(fogEnd - eyez) * fogScale;
+ 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;
+ if (eyez < 0.0)
+ eyez = -eyez;
+ fogcoord[i] = FloatToFixed((fogEnd - eyez) * fogScale);
+ }
+ }
+ else {
+ /* perspective */
+ for (i=0;i<n;i++) {
+ GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
+ GLfloat eyez = p14 / (ndcz + p10);
+ if (eyez < 0.0)
+ eyez = -eyez;
+ fogcoord[i] = FloatToFixed((fogEnd - eyez) * fogScale);
+ }
}
}
break;
case GL_EXP:
- for (i=0;i<n;i++) {
- GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
- GLfloat eyez = d / (c+ndcz);
- if (eyez < 0.0) eyez = -eyez;
- fogcoord[i] = FloatToFixed(exp( -ctx->Fog.Density * eyez ));
- }
+ 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;
+ fogcoord[i] = FloatToFixed(exp( -ctx->Fog.Density * eyez ));
+ }
+ }
+ else {
+ /* perspective */
+ for (i=0;i<n;i++) {
+ GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
+ GLfloat eyez = p14 / (ndcz + p10);
+ if (eyez < 0.0)
+ eyez = -eyez;
+ fogcoord[i] = FloatToFixed(exp( -ctx->Fog.Density * eyez ));
+ }
+ }
break;
case GL_EXP2:
{
GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
- for (i=0;i<n;i++) {
- GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
- GLfloat eyez = d / (c+ndcz);
- GLfloat tmp = negDensitySquared * eyez * eyez;
+ 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)
+ /* XXX this underflow check may be needed for other systems*/
+ if (tmp < FLT_MIN_10_EXP)
+ tmp = FLT_MIN_10_EXP;
+#endif
+ fogcoord[i] = FloatToFixed(exp( tmp ));
+ }
+ }
+ else {
+ /* perspective */
+ 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)
- /* XXX this underflow check may be needed for other systems */
- if (tmp < FLT_MIN_10_EXP)
- tmp = FLT_MIN_10_EXP;
+ /* XXX this underflow check may be needed for other systems*/
+ if (tmp < FLT_MIN_10_EXP)
+ tmp = FLT_MIN_10_EXP;
#endif
- fogcoord[i] = FloatToFixed(exp( tmp ));
+ fogcoord[i] = FloatToFixed(exp( tmp ));
+ }
}
}
break;
default:
- gl_problem(ctx, "Bad fog mode in _mesa_win_fog_coords_from_z");
+ _mesa_problem(ctx, "Bad fog mode in _mesa_win_fog_coords_from_z");
return;
}
}
_mesa_depth_fog_rgba_pixels( const GLcontext *ctx,
GLuint n, const GLdepth z[], GLchan rgba[][4] )
{
- GLfixed fog[MAX_WIDTH];
+ GLfixed fog[PB_SIZE];
+ ASSERT(n <= PB_SIZE);
_mesa_win_fog_coords_from_z( ctx, n, z, fog );
_mesa_fog_rgba_pixels( ctx, n, fog, rgba );
}
_mesa_depth_fog_ci_pixels( const GLcontext *ctx,
GLuint n, const GLdepth z[], GLuint index[] )
{
- GLfixed fog[MAX_WIDTH];
+ GLfixed fog[PB_SIZE];
+ ASSERT(n <= PB_SIZE);
_mesa_win_fog_coords_from_z( ctx, n, z, fog );
_mesa_fog_ci_pixels( ctx, n, fog, index );
}
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