radeon: share common fog code between radeon and r200

Signed-off-by: Alex Deucher <[email protected]>

1 files changed, 125 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/radeon/radeon_fog.c b/src/mesa/drivers/dri/radeon/radeon_fog.c
new file mode 100644
index 00000000000..bd2642b1304
--- /dev/null
+++ b/src/mesa/drivers/dri/radeon/radeon_fog.c
@@ -0,0 +1,125 @@
+/**************************************************************************
+
+Copyright 2000, 2001 ATI Technologies Inc., Ontario, Canada, and
+                     Tungsten Graphics Inc., Austin, Texas.
+
+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 (including the
+next paragraph) 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 THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS 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.
+
+**************************************************************************/
+
+/*
+ * Authors:
+ *   Keith Whitwell <[email protected]>
+ */
+
+#include "main/glheader.h"
+#include "main/imports.h"
+#include "main/context.h"
+#include "main/mtypes.h"
+#include "main/enums.h"
+#include "main/macros.h"
+
+#include "radeon_fog.h"
+
+/**********************************************************************/
+/*             Fog blend factor computation for hw tcl                */
+/*             same calculation used as in t_vb_fog.c                 */
+/**********************************************************************/
+
+#define FOG_EXP_TABLE_SIZE 256
+#define FOG_MAX (10.0)
+#define EXP_FOG_MAX .0006595
+#define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE)
+static GLfloat exp_table[FOG_EXP_TABLE_SIZE];
+
+#if 1
+#define NEG_EXP( result, narg )						\
+do {									\
+   GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR));			\
+   GLint k = (GLint) f;							\
+   if (k > FOG_EXP_TABLE_SIZE-2) 					\
+      result = (GLfloat) EXP_FOG_MAX;					\
+   else									\
+      result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]);	\
+} while (0)
+#else
+#define NEG_EXP( result, narg )					\
+do {								\
+   result = exp(-narg);						\
+} while (0)
+#endif
+
+
+/**
+ * Initialize the exp_table[] lookup table for approximating exp().
+ */
+void
+radeonInitStaticFogData( void )
+{
+   GLfloat f = 0.0F;
+   GLint i = 0;
+   for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) {
+      exp_table[i] = (GLfloat) exp(-f);
+   }
+}
+
+/**
+ * Compute per-vertex fog blend factors from fog coordinates by
+ * evaluating the GL_LINEAR, GL_EXP or GL_EXP2 fog function.
+ * Fog coordinates are distances from the eye (typically between the
+ * near and far clip plane distances).
+ * Note the fog (eye Z) coords may be negative so we use ABS(z) below.
+ * Fog blend factors are in the range [0,1].
+ */
+float
+radeonComputeFogBlendFactor( struct gl_context *ctx, GLfloat fogcoord )
+{
+	GLfloat end  = ctx->Fog.End;
+	GLfloat d, temp;
+	const GLfloat z = FABSF(fogcoord);
+
+	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);
+		temp = (end - z) * d;
+		return CLAMP(temp, 0.0F, 1.0F);
+		break;
+	case GL_EXP:
+		d = ctx->Fog.Density;
+		NEG_EXP( temp, d * z );
+		return temp;
+		break;
+	case GL_EXP2:
+		d = ctx->Fog.Density*ctx->Fog.Density;
+		NEG_EXP( temp, d * z * z );
+		return temp;
+		break;
+	default:
+		_mesa_problem(ctx, "Bad fog mode in make_fog_coord");
+		return 0;
+	}
+}
+