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| 4358 | Serge | 1 | /************************************************************************** |
| 2 | |||
| 3 | Copyright 2000, 2001 ATI Technologies Inc., Ontario, Canada, and |
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| 4 | Tungsten Graphics Inc., Austin, Texas. |
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| 5 | |||
| 6 | All Rights Reserved. |
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| 7 | |||
| 8 | Permission is hereby granted, free of charge, to any person obtaining |
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| 9 | a copy of this software and associated documentation files (the |
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| 10 | "Software"), to deal in the Software without restriction, including |
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| 11 | without limitation the rights to use, copy, modify, merge, publish, |
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| 12 | distribute, sublicense, and/or sell copies of the Software, and to |
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| 13 | permit persons to whom the Software is furnished to do so, subject to |
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| 14 | the following conditions: |
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| 15 | |||
| 16 | The above copyright notice and this permission notice (including the |
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| 17 | next paragraph) shall be included in all copies or substantial |
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| 18 | portions of the Software. |
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| 19 | |||
| 20 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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| 21 | EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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| 22 | MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
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| 23 | IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE |
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| 24 | LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
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| 25 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
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| 26 | WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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| 27 | |||
| 28 | **************************************************************************/ |
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| 29 | |||
| 30 | /* |
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| 31 | * Authors: |
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| 32 | * Keith Whitwell |
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| 33 | */ |
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| 34 | |||
| 35 | #include "main/glheader.h" |
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| 36 | #include "main/imports.h" |
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| 37 | #include "main/context.h" |
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| 38 | #include "main/mtypes.h" |
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| 39 | #include "main/enums.h" |
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| 40 | #include "main/macros.h" |
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| 41 | |||
| 42 | #include "radeon_fog.h" |
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| 43 | |||
| 44 | /**********************************************************************/ |
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| 45 | /* Fog blend factor computation for hw tcl */ |
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| 46 | /* same calculation used as in t_vb_fog.c */ |
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| 47 | /**********************************************************************/ |
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| 48 | |||
| 49 | #define FOG_EXP_TABLE_SIZE 256 |
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| 50 | #define FOG_MAX (10.0) |
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| 51 | #define EXP_FOG_MAX .0006595 |
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| 52 | #define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE) |
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| 53 | static GLfloat exp_table[FOG_EXP_TABLE_SIZE]; |
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| 54 | |||
| 55 | #if 1 |
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| 56 | #define NEG_EXP( result, narg ) \ |
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| 57 | do { \ |
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| 58 | GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR)); \ |
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| 59 | GLint k = (GLint) f; \ |
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| 60 | if (k > FOG_EXP_TABLE_SIZE-2) \ |
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| 61 | result = (GLfloat) EXP_FOG_MAX; \ |
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| 62 | else \ |
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| 63 | result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \ |
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| 64 | } while (0) |
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| 65 | #else |
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| 66 | #define NEG_EXP( result, narg ) \ |
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| 67 | do { \ |
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| 68 | result = exp(-narg); \ |
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| 69 | } while (0) |
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| 70 | #endif |
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| 71 | |||
| 72 | |||
| 73 | /** |
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| 74 | * Initialize the exp_table[] lookup table for approximating exp(). |
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| 75 | */ |
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| 76 | void |
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| 77 | radeonInitStaticFogData( void ) |
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| 78 | { |
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| 79 | GLfloat f = 0.0F; |
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| 80 | GLint i = 0; |
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| 81 | for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) { |
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| 82 | exp_table[i] = (GLfloat) exp(-f); |
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| 83 | } |
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| 84 | } |
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| 85 | |||
| 86 | /** |
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| 87 | * Compute per-vertex fog blend factors from fog coordinates by |
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| 88 | * evaluating the GL_LINEAR, GL_EXP or GL_EXP2 fog function. |
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| 89 | * Fog coordinates are distances from the eye (typically between the |
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| 90 | * near and far clip plane distances). |
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| 91 | * Note the fog (eye Z) coords may be negative so we use ABS(z) below. |
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| 92 | * Fog blend factors are in the range [0,1]. |
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| 93 | */ |
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| 94 | float |
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| 95 | radeonComputeFogBlendFactor( struct gl_context *ctx, GLfloat fogcoord ) |
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| 96 | { |
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| 97 | GLfloat end = ctx->Fog.End; |
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| 98 | GLfloat d, temp; |
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| 99 | const GLfloat z = FABSF(fogcoord); |
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| 100 | |||
| 101 | switch (ctx->Fog.Mode) { |
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| 102 | case GL_LINEAR: |
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| 103 | if (ctx->Fog.Start == ctx->Fog.End) |
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| 104 | d = 1.0F; |
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| 105 | else |
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| 106 | d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); |
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| 107 | temp = (end - z) * d; |
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| 108 | return CLAMP(temp, 0.0F, 1.0F); |
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| 109 | break; |
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| 110 | case GL_EXP: |
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| 111 | d = ctx->Fog.Density; |
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| 112 | NEG_EXP( temp, d * z ); |
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| 113 | return temp; |
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| 114 | break; |
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| 115 | case GL_EXP2: |
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| 116 | d = ctx->Fog.Density*ctx->Fog.Density; |
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| 117 | NEG_EXP( temp, d * z * z ); |
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| 118 | return temp; |
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| 119 | break; |
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| 120 | default: |
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| 121 | _mesa_problem(ctx, "Bad fog mode in make_fog_coord"); |
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| 122 | return 0; |
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| 123 | } |
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| 124 | } |
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| 125 |