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
  28 /*
  29  * Authors:
  30  *   Sung-Ching Lin <sclin@sis.com.tw>
  31  *   Eric Anholt <anholt@FreeBSD.org>
  32  */
  33
  34 #include "sis_context.h"
  35 #include "sis_state.h"
  36 #include "swrast/swrast.h"
  37
  38 #include "main/macros.h"
  39
  40 static GLint convertFtToFogFt( GLfloat dwInValue );
  41 static GLint doFPtoFixedNoRound( GLfloat dwInValue, int nFraction );
  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_COORDINATE_SOURCE_EXT:
  56       current->hwFog &= ~MASK_FogMode;
  57       switch (ctx->Fog.FogCoordinateSource)
  58       {
  59       case GL_FOG_COORDINATE_EXT:
  60          current->hwFog &= ~MASK_FogZLookup;
  61          break;
  62       case GL_FRAGMENT_DEPTH_EXT:
  63          current->hwFog |= MASK_FogZLookup;
  64          break;
  65       }
  66       if (current->hwFog != prev->hwFog) {
  67          prev->hwFog = current->hwFog;
  68          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  69       }
  70       break;
  71    case GL_FOG_MODE:
  72       current->hwFog &= ~MASK_FogMode;
  73       switch (ctx->Fog.Mode)
  74       {
  75       case GL_LINEAR:
  76          current->hwFog |= FOGMODE_LINEAR;
  77          break;
  78       case GL_EXP:
  79          current->hwFog |= FOGMODE_EXP;
  80          break;
  81       case GL_EXP2:
  82          current->hwFog |= FOGMODE_EXP2;
  83          break;
  84       }
  85       if (current->hwFog != prev->hwFog) {
  86          prev->hwFog = current->hwFog;
  87          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  88       }
  89       break;
  90    case GL_FOG_DENSITY:
  91       current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
  92       if (current->hwFogDensity != prev->hwFogDensity) {
  93          prev->hwFogDensity = current->hwFogDensity;
  94          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  95       }
  96       break;
  97    case GL_FOG_START:
  98    case GL_FOG_END:
  99       fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
 100       current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
 101       if (pname == GL_FOG_END)
 102       {
 103          if (smesa->Chipset == PCI_CHIP_SIS300)
 104             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
 105          else
 106             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
 107       }
 108       if (current->hwFogFar != prev->hwFogFar ||
 109           current->hwFogInverse != prev->hwFogInverse)
 110       {
 111          prev->hwFogFar = current->hwFogFar;
 112          prev->hwFogInverse = current->hwFogInverse;
 113          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 114       }
 115       break;
 116    case GL_FOG_INDEX:
 117       /* TODO */
 118       break;
 119    case GL_FOG_COLOR:
 120       fogColor  = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
 121       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
 122       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
 123       current->hwFog &= 0xff000000;
 124       current->hwFog |= fogColor;
 125       if (current->hwFog != prev->hwFog) {
 126           prev->hwFog = current->hwFog;
 127          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 128       }
 129       break;
 130    }
 131 }
 132
 133 static GLint
 134 doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
 135 {
 136    GLint dwMantissa;
 137    int nTemp;
 138    union { int i; float f; } u;
 139    GLint val;
 140
 141    u.f = dwInValue;
 142    val = u.i;
 143
 144    if (val == 0)
 145       return 0;
 146    nTemp = (int) (val & 0x7F800000) >> 23;
 147    nTemp = nTemp - 127 + nFraction - 23;
 148    dwMantissa = (val & 0x007FFFFF) | 0x00800000;
 149
 150    if (nTemp < -25)
 151        return 0;
 152    if (nTemp > 0)
 153       dwMantissa <<= nTemp;
 154    else {
 155       nTemp = -nTemp;
 156       dwMantissa >>= nTemp;
 157    }
 158    if (val & 0x80000000)
 159       dwMantissa = ~dwMantissa + 1;
 160    return dwMantissa;
 161 }
 162
 163 /* s[8].23->s[7].10 */
 164 static GLint
 165 convertFtToFogFt( GLfloat dwInValue )
 166 {
 167    GLint dwMantissa, dwExp;
 168    GLint dwRet;
 169    union { int i; float f; } u;
 170    GLint val;
 171
 172    u.f = dwInValue;
 173    val = u.i;
 174
 175    if (val == 0)
 176       return 0;
 177
 178    /* ----- Standard float Format: s[8].23                          -----
 179     * -----     = (-1)^S * 2^(E      - 127) * (1 + M        / 2^23) -----
 180     * -----     = (-1)^S * 2^((E-63) -  64) * (1 + (M/2^13) / 2^10) -----
 181     * ----- Density float Format:  s[7].10                          -----
 182     * -----     New Exponential = E - 63                            -----
 183     * -----     New Mantissa    = M / 2^13                          -----
 184     * -----                                                         -----
 185     */
 186
 187    dwExp = (val & 0x7F800000) >> 23;
 188    dwExp -= 63;
 189
 190    if (dwExp < 0)
 191       return 0;
 192
 193    if (dwExp <= 0x7F)
 194       dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
 195    else {
 196       /* ----- To Return +Max(or -Max) ----- */
 197       dwExp = 0x7F;
 198       dwMantissa = 0x3FF;
 199    }
 200
 201    dwRet = (val & 0x80000000) >> (31 - 17);  /* Shift Sign Bit */
 202
 203    dwRet |= (dwExp << 10) | dwMantissa;
 204
 205    return dwRet;
 206 }