src/mesa/drivers/dri/sis/sis_fog.c

   1 /**************************************************************************
   2
   3 Copyright 2000 Silicon Integrated Systems Corp, Inc., HsinChu, Taiwan.
   4 Copyright 2003 Eric Anholt
   5 All Rights Reserved.
   6
   7 Permission is hereby granted, free of charge, to any person obtaining a
   8 copy of this software and associated documentation files (the "Software"),
   9 to deal in the Software without restriction, including without limitation
  10 on the rights to use, copy, modify, merge, publish, distribute, sub
  11 license, and/or sell copies of the Software, and to permit persons to whom
  12 the Software is furnished to do so, subject to the following conditions:
  13
  14 The above copyright notice and this permission notice (including the next
  15 paragraph) shall be included in all copies or substantial portions of the
  16 Software.
  17
  18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21 ERIC ANHOLT OR SILICON INTEGRATED SYSTEMS CORP BE LIABLE FOR ANY CLAIM,
  22 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24 USE OR OTHER DEALINGS IN THE SOFTWARE.
  25
  26 **************************************************************************/
  27 /* $XFree86: xc/lib/GL/mesa/src/drv/sis/sis_fog.c,v 1.3 2000/09/26 15:56:48 tsi Exp $ */
  28
  29 /*
  30  * Authors:
  31  *   Sung-Ching Lin <sclin@sis.com.tw>
  32  *   Eric Anholt <anholt@FreeBSD.org>
  33  */
  34
  35 #include "sis_context.h"
  36 #include "sis_state.h"
  37 #include "swrast/swrast.h"
  38
  39 #include "macros.h"
  40
  41 static GLint convertFtToFogFt( GLfloat dwInValue );
  42
  43 void
  44 sisDDFogfv( GLcontext *ctx, GLenum pname, const GLfloat *params )
  45 {
  46    sisContextPtr smesa = SIS_CONTEXT(ctx);
  47    __GLSiSHardware *prev = &smesa->prev;
  48    __GLSiSHardware *current = &smesa->current;
  49
  50    float fArg;
  51    GLint fogColor;
  52
  53    switch (pname)
  54    {
  55    case GL_FOG_MODE:
  56       current->hwFog &= ~MASK_FogMode;
  57       switch (ctx->Fog.Mode)
  58       {
  59       case GL_LINEAR:
  60          current->hwFog |= FOGMODE_LINEAR;
  61          break;
  62       case GL_EXP:
  63          current->hwFog |= FOGMODE_EXP;
  64          break;
  65       case GL_EXP2:
  66          current->hwFog |= FOGMODE_EXP2;
  67          break;
  68       }
  69       if (current->hwFog != prev->hwFog) {
  70          prev->hwFog = current->hwFog;
  71          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  72       }
  73       break;
  74    case GL_FOG_DENSITY:
  75       current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
  76       if (current->hwFogDensity != prev->hwFogDensity) {
  77          prev->hwFogDensity = current->hwFogDensity;
  78          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  79       }
  80       break;
  81    case GL_FOG_START:
  82    case GL_FOG_END:
  83       fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
  84       current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
  85       if (pname == GL_FOG_END)
  86       {
  87          if (smesa->Chipset == PCI_CHIP_SIS300)
  88             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
  89          else
  90             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
  91       }
  92       if (current->hwFogFar != prev->hwFogFar ||
  93           current->hwFogInverse != prev->hwFogInverse)
  94       {
  95          prev->hwFogFar = current->hwFogFar;
  96          prev->hwFogInverse = current->hwFogInverse;
  97          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  98       }
  99       break;
 100    case GL_FOG_INDEX:
 101       /* TODO */
 102       break;
 103    case GL_FOG_COLOR:
 104       fogColor  = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
 105       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
 106       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
 107       current->hwFog &= 0xff000000;
 108       current->hwFog |= fogColor;
 109       if (current->hwFog != prev->hwFog) {
 110           prev->hwFog = current->hwFog;
 111          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 112       }
 113       break;
 114    }
 115 }
 116
 117 GLint
 118 doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
 119 {
 120    GLint dwMantissa;
 121    int nTemp;
 122    union { int i; float f; } u;
 123    GLint val;
 124
 125    u.f = dwInValue;
 126    val = u.i;
 127
 128    if (val == 0)
 129       return 0;
 130    nTemp = (int) (val & 0x7F800000) >> 23;
 131    nTemp = nTemp - 127 + nFraction - 23;
 132    dwMantissa = (val & 0x007FFFFF) | 0x00800000;
 133
 134    if (nTemp < -25)
 135        return 0;
 136    if (nTemp > 0)
 137       dwMantissa <<= nTemp;
 138    else {
 139       nTemp = -nTemp;
 140       dwMantissa >>= nTemp;
 141    }
 142    if (val & 0x80000000)
 143       dwMantissa = ~dwMantissa + 1;
 144    return dwMantissa;
 145 }
 146
 147 /* s[8].23->s[7].10 */
 148 static GLint
 149 convertFtToFogFt( GLfloat dwInValue )
 150 {
 151    GLint dwMantissa, dwExp;
 152    GLint dwRet;
 153    union { int i; float f; } u;
 154    GLint val;
 155
 156    u.f = dwInValue;
 157    val = u.i;
 158
 159    if (val == 0)
 160       return 0;
 161
 162    /* ----- Standard float Format: s[8].23                          -----
 163     * -----     = (-1)^S * 2^(E      - 127) * (1 + M        / 2^23) -----
 164     * -----     = (-1)^S * 2^((E-63) -  64) * (1 + (M/2^13) / 2^10) -----
 165     * ----- Density float Format:  s[7].10                          -----
 166     * -----     New Exponential = E - 63                            -----
 167     * -----     New Mantissa    = M / 2^13                          -----
 168     * -----                                                         -----
 169     */
 170
 171    dwExp = (val & 0x7F800000) >> 23;
 172    dwExp -= 63;
 173
 174    if (dwExp < 0)
 175       return 0;
 176
 177    if (dwExp <= 0x7F)
 178       dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
 179    else {
 180       /* ----- To Return +Max(or -Max) ----- */
 181       dwExp = 0x7F;
 182       dwMantissa = 0x3FF;
 183    }
 184
 185    dwRet = (val & 0x80000000) >> (31 - 17);  /* Shift Sign Bit */
 186
 187    dwRet |= (dwExp << 10) | dwMantissa;
 188
 189    return dwRet;
 190 }