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 static GLint doFPtoFixedNoRound( GLfloat dwInValue, int nFraction );
  43
  44 void
  45 sisDDFogfv( GLcontext *ctx, GLenum pname, const GLfloat *params )
  46 {
  47    sisContextPtr smesa = SIS_CONTEXT(ctx);
  48    __GLSiSHardware *prev = &smesa->prev;
  49    __GLSiSHardware *current = &smesa->current;
  50
  51    float fArg;
  52    GLint fogColor;
  53
  54    switch (pname)
  55    {
  56    case GL_FOG_MODE:
  57       current->hwFog &= ~MASK_FogMode;
  58       switch (ctx->Fog.Mode)
  59       {
  60       case GL_LINEAR:
  61          current->hwFog |= FOGMODE_LINEAR;
  62          break;
  63       case GL_EXP:
  64          current->hwFog |= FOGMODE_EXP;
  65          break;
  66       case GL_EXP2:
  67          current->hwFog |= FOGMODE_EXP2;
  68          break;
  69       }
  70       if (current->hwFog != prev->hwFog) {
  71          prev->hwFog = current->hwFog;
  72          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  73       }
  74       break;
  75    case GL_FOG_DENSITY:
  76       current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
  77       if (current->hwFogDensity != prev->hwFogDensity) {
  78          prev->hwFogDensity = current->hwFogDensity;
  79          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  80       }
  81       break;
  82    case GL_FOG_START:
  83    case GL_FOG_END:
  84       fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
  85       current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
  86       if (pname == GL_FOG_END)
  87       {
  88          if (smesa->Chipset == PCI_CHIP_SIS300)
  89             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
  90          else
  91             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
  92       }
  93       if (current->hwFogFar != prev->hwFogFar ||
  94           current->hwFogInverse != prev->hwFogInverse)
  95       {
  96          prev->hwFogFar = current->hwFogFar;
  97          prev->hwFogInverse = current->hwFogInverse;
  98          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  99       }
 100       break;
 101    case GL_FOG_INDEX:
 102       /* TODO */
 103       break;
 104    case GL_FOG_COLOR:
 105       fogColor  = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
 106       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
 107       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
 108       current->hwFog &= 0xff000000;
 109       current->hwFog |= fogColor;
 110       if (current->hwFog != prev->hwFog) {
 111           prev->hwFog = current->hwFog;
 112          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 113       }
 114       break;
 115    }
 116 }
 117
 118 static GLint
 119 doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
 120 {
 121    GLint dwMantissa;
 122    int nTemp;
 123    union { int i; float f; } u;
 124    GLint val;
 125
 126    u.f = dwInValue;
 127    val = u.i;
 128
 129    if (val == 0)
 130       return 0;
 131    nTemp = (int) (val & 0x7F800000) >> 23;
 132    nTemp = nTemp - 127 + nFraction - 23;
 133    dwMantissa = (val & 0x007FFFFF) | 0x00800000;
 134
 135    if (nTemp < -25)
 136        return 0;
 137    if (nTemp > 0)
 138       dwMantissa <<= nTemp;
 139    else {
 140       nTemp = -nTemp;
 141       dwMantissa >>= nTemp;
 142    }
 143    if (val & 0x80000000)
 144       dwMantissa = ~dwMantissa + 1;
 145    return dwMantissa;
 146 }
 147
 148 /* s[8].23->s[7].10 */
 149 static GLint
 150 convertFtToFogFt( GLfloat dwInValue )
 151 {
 152    GLint dwMantissa, dwExp;
 153    GLint dwRet;
 154    union { int i; float f; } u;
 155    GLint val;
 156
 157    u.f = dwInValue;
 158    val = u.i;
 159
 160    if (val == 0)
 161       return 0;
 162
 163    /* ----- Standard float Format: s[8].23                          -----
 164     * -----     = (-1)^S * 2^(E      - 127) * (1 + M        / 2^23) -----
 165     * -----     = (-1)^S * 2^((E-63) -  64) * (1 + (M/2^13) / 2^10) -----
 166     * ----- Density float Format:  s[7].10                          -----
 167     * -----     New Exponential = E - 63                            -----
 168     * -----     New Mantissa    = M / 2^13                          -----
 169     * -----                                                         -----
 170     */
 171
 172    dwExp = (val & 0x7F800000) >> 23;
 173    dwExp -= 63;
 174
 175    if (dwExp < 0)
 176       return 0;
 177
 178    if (dwExp <= 0x7F)
 179       dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
 180    else {
 181       /* ----- To Return +Max(or -Max) ----- */
 182       dwExp = 0x7F;
 183       dwMantissa = 0x3FF;
 184    }
 185
 186    dwRet = (val & 0x80000000) >> (31 - 17);  /* Shift Sign Bit */
 187
 188    dwRet |= (dwExp << 10) | dwMantissa;
 189
 190    return dwRet;
 191 }