0,0 → 1,127 |
/************************************************************************** |
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Copyright 2000, 2001 ATI Technologies Inc., Ontario, Canada, and |
VMware, Inc. |
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All Rights Reserved. |
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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: |
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The above copyright notice and this permission notice (including the |
next paragraph) shall be included in all copies or substantial |
portions of the Software. |
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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. |
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**************************************************************************/ |
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/* |
* Authors: |
* Keith Whitwell <keithw@vmware.com> |
*/ |
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#include "c99_math.h" |
#include "main/glheader.h" |
#include "main/imports.h" |
#include "main/context.h" |
#include "main/mtypes.h" |
#include "main/enums.h" |
#include "main/macros.h" |
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#include "radeon_screen.h" |
#include "radeon_fog.h" |
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/**********************************************************************/ |
/* Fog blend factor computation for hw tcl */ |
/* same calculation used as in t_vb_fog.c */ |
/**********************************************************************/ |
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#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]; |
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#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 |
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/** |
* 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); |
} |
} |
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/** |
* 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); |
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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; |
} |
} |
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