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| Rev | Author | Line No. | Line |
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| 5564 | serge | 1 | /************************************************************************** |
| 2 | |||
| 3 | Copyright 2000, 2001 ATI Technologies Inc., Ontario, Canada, and |
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| 4 | VMware, Inc. |
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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 "c99_math.h" |
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| 36 | #include "main/glheader.h" |
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| 37 | #include "main/imports.h" |
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| 38 | #include "main/context.h" |
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| 39 | #include "main/mtypes.h" |
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| 40 | #include "main/enums.h" |
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| 41 | #include "main/macros.h" |
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| 42 | |||
| 43 | #include "radeon_screen.h" |
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| 44 | #include "radeon_fog.h" |
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| 45 | |||
| 46 | /**********************************************************************/ |
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| 47 | /* Fog blend factor computation for hw tcl */ |
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| 48 | /* same calculation used as in t_vb_fog.c */ |
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| 49 | /**********************************************************************/ |
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| 50 | |||
| 51 | #define FOG_EXP_TABLE_SIZE 256 |
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| 52 | #define FOG_MAX (10.0) |
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| 53 | #define EXP_FOG_MAX .0006595 |
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| 54 | #define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE) |
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| 55 | static GLfloat exp_table[FOG_EXP_TABLE_SIZE]; |
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| 56 | |||
| 57 | #if 1 |
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| 58 | #define NEG_EXP( result, narg ) \ |
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| 59 | do { \ |
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| 60 | GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR)); \ |
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| 61 | GLint k = (GLint) f; \ |
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| 62 | if (k > FOG_EXP_TABLE_SIZE-2) \ |
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| 63 | result = (GLfloat) EXP_FOG_MAX; \ |
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| 64 | else \ |
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| 65 | result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \ |
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| 66 | } while (0) |
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| 67 | #else |
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| 68 | #define NEG_EXP( result, narg ) \ |
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| 69 | do { \ |
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| 70 | result = exp(-narg); \ |
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| 71 | } while (0) |
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| 72 | #endif |
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| 73 | |||
| 74 | |||
| 75 | /** |
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| 76 | * Initialize the exp_table[] lookup table for approximating exp(). |
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| 77 | */ |
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| 78 | void |
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| 79 | radeonInitStaticFogData( void ) |
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| 80 | { |
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| 81 | GLfloat f = 0.0F; |
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| 82 | GLint i = 0; |
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| 83 | for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) { |
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| 84 | exp_table[i] = (GLfloat) exp(-f); |
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| 85 | } |
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| 86 | } |
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| 87 | |||
| 88 | /** |
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| 89 | * Compute per-vertex fog blend factors from fog coordinates by |
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| 90 | * evaluating the GL_LINEAR, GL_EXP or GL_EXP2 fog function. |
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| 91 | * Fog coordinates are distances from the eye (typically between the |
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| 92 | * near and far clip plane distances). |
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| 93 | * Note the fog (eye Z) coords may be negative so we use ABS(z) below. |
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| 94 | * Fog blend factors are in the range [0,1]. |
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| 95 | */ |
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| 96 | float |
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| 97 | radeonComputeFogBlendFactor( struct gl_context *ctx, GLfloat fogcoord ) |
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| 98 | { |
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| 99 | GLfloat end = ctx->Fog.End; |
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| 100 | GLfloat d, temp; |
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| 101 | const GLfloat z = fabsf(fogcoord); |
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| 102 | |||
| 103 | switch (ctx->Fog.Mode) { |
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| 104 | case GL_LINEAR: |
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| 105 | if (ctx->Fog.Start == ctx->Fog.End) |
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| 106 | d = 1.0F; |
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| 107 | else |
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| 108 | d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); |
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| 109 | temp = (end - z) * d; |
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| 110 | return CLAMP(temp, 0.0F, 1.0F); |
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| 111 | break; |
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| 112 | case GL_EXP: |
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| 113 | d = ctx->Fog.Density; |
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| 114 | NEG_EXP( temp, d * z ); |
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| 115 | return temp; |
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| 116 | break; |
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| 117 | case GL_EXP2: |
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| 118 | d = ctx->Fog.Density*ctx->Fog.Density; |
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| 119 | NEG_EXP( temp, d * z * z ); |
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| 120 | return temp; |
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| 121 | break; |
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| 122 | default: |
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| 123 | _mesa_problem(ctx, "Bad fog mode in make_fog_coord"); |
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| 124 | return 0; |
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| 125 | } |
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| 126 | } |
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| 127 |