From e3a051e0538a605551f4d58294c94f5eb00ed07f Mon Sep 17 00:00:00 2001
From: Keith Whitwell <keith@tungstengraphics.com>
Date: Tue, 31 Oct 2000 18:00:04 +0000
Subject: Moved software rasterizer functionality to new directory.

---
 src/mesa/swrast/s_fog.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 188 insertions(+)
 create mode 100644 src/mesa/swrast/s_fog.c

(limited to 'src/mesa/swrast/s_fog.c')

diff --git a/src/mesa/swrast/s_fog.c b/src/mesa/swrast/s_fog.c
new file mode 100644
index 0000000000..32fafe617c
--- /dev/null
+++ b/src/mesa/swrast/s_fog.c
@@ -0,0 +1,188 @@
+/* $Id: s_fog.c,v 1.1 2000/10/31 18:00:04 keithw Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  3.5
+ * 
+ * Copyright (C) 1999-2000  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.
+ */
+
+
+#include "glheader.h"
+#include "colormac.h"
+#include "context.h"
+#include "macros.h"
+#include "mmath.h"
+
+#include "s_fog.h"
+
+
+/*
+ * Apply fog to an array of RGBA pixels.
+ * Input:  n - number of pixels
+ *         fog - array of interpolated screen-space fog coordinates in [0..1]
+ *         red, green, blue, alpha - pixel colors
+ * Output:  red, green, blue, alpha - fogged pixel colors
+ */
+void
+_mesa_fog_rgba_pixels( const GLcontext *ctx,
+                       GLuint n, 
+		       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;
+
+   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;
+   }
+}
+
+
+
+
+/*
+ * Apply fog to an array of color index pixels.
+ * Input:  n - number of pixels
+ *         z - array of integer depth values
+ *         index - pixel color indexes
+ * Output:  index - fogged pixel color indexes
+ */
+void
+_mesa_fog_ci_pixels( const GLcontext *ctx,
+                     GLuint n, const GLfixed fog[], GLuint index[] )
+{
+   GLuint idx = ctx->Fog.Index;
+   GLuint i;
+
+   for (i=0;i<n;i++) {
+      GLfixed f = FixedToFloat(CLAMP(fog[i], 0, FIXED_ONE));
+      index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * idx);
+   }
+}
+
+
+
+/*
+ * Calculate fog coords from window z values 
+ * Input:  n - number of pixels
+ *         z - array of integer depth values
+ *         red, green, blue, alpha - pixel colors
+ * Output:  red, green, blue, alpha - fogged pixel colors
+ *
+ * Use lookup table & interpolation? 
+ */
+void
+_mesa_win_fog_coords_from_z( const GLcontext *ctx,
+			     GLuint n, 
+			     const GLdepth z[], 
+			     GLfixed fogcoord[] )
+{
+   GLfloat c = ctx->ProjectionMatrix.m[10];
+   GLfloat d = ctx->ProjectionMatrix.m[14];
+   GLuint i;
+
+   GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ];
+   GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ];
+
+   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;
+            }
+         }
+	 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 ));
+	 }
+	 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 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 ));
+            }
+         }
+	 break;
+      default:
+         gl_problem(ctx, "Bad fog mode in _mesa_win_fog_coords_from_z");
+         return;
+   }
+}
+
+
+/*
+ * Apply fog to an array of RGBA pixels.
+ * Input:  n - number of pixels
+ *         z - array of integer depth values
+ *         red, green, blue, alpha - pixel colors
+ * Output:  red, green, blue, alpha - fogged pixel colors
+ */
+void
+_mesa_depth_fog_rgba_pixels( const GLcontext *ctx,
+			     GLuint n, const GLdepth z[], GLchan rgba[][4] )
+{
+   GLfixed fog[MAX_WIDTH];
+   _mesa_win_fog_coords_from_z( ctx, n, z, fog );
+   _mesa_fog_rgba_pixels( ctx, n, fog, rgba );
+}
+
+
+/*
+ * Apply fog to an array of color index pixels.
+ * Input:  n - number of pixels
+ *         z - array of integer depth values
+ *         index - pixel color indexes
+ * Output:  index - fogged pixel color indexes
+ */
+void
+_mesa_depth_fog_ci_pixels( const GLcontext *ctx,
+                     GLuint n, const GLdepth z[], GLuint index[] )
+{
+   GLfixed fog[MAX_WIDTH];
+   _mesa_win_fog_coords_from_z( ctx, n, z, fog );
+   _mesa_fog_ci_pixels( ctx, n, fog, index );
+}
+
-- 
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