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
  37 #include "main/macros.h"
  38
  39 static GLint convertFtToFogFt( GLfloat dwInValue );
  40 static GLint doFPtoFixedNoRound( GLfloat dwInValue, int nFraction );
  41
  42 void
  43 sisDDFogfv( struct gl_context *ctx, GLenum pname, const GLfloat *params )
  44 {
  45    sisContextPtr smesa = SIS_CONTEXT(ctx);
  46    __GLSiSHardware *prev = &smesa->prev;
  47    __GLSiSHardware *current = &smesa->current;
  48
  49    float fArg;
  50    GLint fogColor;
  51
  52    switch (pname)
  53    {
  54    case GL_FOG_COORDINATE_SOURCE_EXT:
  55       current->hwFog &= ~MASK_FogMode;
  56       switch (ctx->Fog.FogCoordinateSource)
  57       {
  58       case GL_FOG_COORDINATE_EXT:
  59          current->hwFog &= ~MASK_FogZLookup;
  60          break;
  61       case GL_FRAGMENT_DEPTH_EXT:
  62          current->hwFog |= MASK_FogZLookup;
  63          break;
  64       }
  65       if (current->hwFog != prev->hwFog) {
  66          prev->hwFog = current->hwFog;
  67          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  68       }
  69       break;
  70    case GL_FOG_MODE:
  71       current->hwFog &= ~MASK_FogMode;
  72       switch (ctx->Fog.Mode)
  73       {
  74       case GL_LINEAR:
  75          current->hwFog |= FOGMODE_LINEAR;
  76          break;
  77       case GL_EXP:
  78          current->hwFog |= FOGMODE_EXP;
  79          break;
  80       case GL_EXP2:
  81          current->hwFog |= FOGMODE_EXP2;
  82          break;
  83       }
  84       if (current->hwFog != prev->hwFog) {
  85          prev->hwFog = current->hwFog;
  86          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  87       }
  88       break;
  89    case GL_FOG_DENSITY:
  90       current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
  91       if (current->hwFogDensity != prev->hwFogDensity) {
  92          prev->hwFogDensity = current->hwFogDensity;
  93          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  94       }
  95       break;
  96    case GL_FOG_START:
  97    case GL_FOG_END:
  98       fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
  99       current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
 100       if (pname == GL_FOG_END)
 101       {
 102          if (smesa->Chipset == PCI_CHIP_SIS300)
 103             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
 104          else
 105             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
 106       }
 107       if (current->hwFogFar != prev->hwFogFar ||
 108           current->hwFogInverse != prev->hwFogInverse)
 109       {
 110          prev->hwFogFar = current->hwFogFar;
 111          prev->hwFogInverse = current->hwFogInverse;
 112          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 113       }
 114       break;
 115    case GL_FOG_INDEX:
 116       /* TODO */
 117       break;
 118    case GL_FOG_COLOR:
 119       fogColor  = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
 120       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
 121       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
 122       current->hwFog &= 0xff000000;
 123       current->hwFog |= fogColor;
 124       if (current->hwFog != prev->hwFog) {
 125           prev->hwFog = current->hwFog;
 126          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 127       }
 128       break;
 129    }
 130 }
 131
 132 static GLint
 133 doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
 134 {
 135    GLint dwMantissa;
 136    int nTemp;
 137    union { int i; float f; } u;
 138    GLint val;
 139
 140    u.f = dwInValue;
 141    val = u.i;
 142
 143    if (val == 0)
 144       return 0;
 145    nTemp = (int) (val & 0x7F800000) >> 23;
 146    nTemp = nTemp - 127 + nFraction - 23;
 147    dwMantissa = (val & 0x007FFFFF) | 0x00800000;
 148
 149    if (nTemp < -25)
 150        return 0;
 151    if (nTemp > 0)
 152       dwMantissa <<= nTemp;
 153    else {
 154       nTemp = -nTemp;
 155       dwMantissa >>= nTemp;
 156    }
 157    if (val & 0x80000000)
 158       dwMantissa = ~dwMantissa + 1;
 159    return dwMantissa;
 160 }
 161
 162 /* s[8].23->s[7].10 */
 163 static GLint
 164 convertFtToFogFt( GLfloat dwInValue )
 165 {
 166    GLint dwMantissa, dwExp;
 167    GLint dwRet;
 168    union { int i; float f; } u;
 169    GLint val;
 170
 171    u.f = dwInValue;
 172    val = u.i;
 173
 174    if (val == 0)
 175       return 0;
 176
 177    /* ----- Standard float Format: s[8].23                          -----
 178     * -----     = (-1)^S * 2^(E      - 127) * (1 + M        / 2^23) -----
 179     * -----     = (-1)^S * 2^((E-63) -  64) * (1 + (M/2^13) / 2^10) -----
 180     * ----- Density float Format:  s[7].10                          -----
 181     * -----     New Exponential = E - 63                            -----
 182     * -----     New Mantissa    = M / 2^13                          -----
 183     * -----                                                         -----
 184     */
 185
 186    dwExp = (val & 0x7F800000) >> 23;
 187    dwExp -= 63;
 188
 189    if (dwExp < 0)
 190       return 0;
 191
 192    if (dwExp <= 0x7F)
 193       dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
 194    else {
 195       /* ----- To Return +Max(or -Max) ----- */
 196       dwExp = 0x7F;
 197       dwMantissa = 0x3FF;
 198    }
 199
 200    dwRet = (val & 0x80000000) >> (31 - 17);  /* Shift Sign Bit */
 201
 202    dwRet |= (dwExp << 10) | dwMantissa;
 203
 204    return dwRet;
 205 }