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_COORDINATE_SOURCE_EXT:
  57       current->hwFog &= ~MASK_FogMode;
  58       switch (ctx->Fog.FogCoordinateSource)
  59       {
  60       case GL_FOG_COORDINATE_EXT:
  61          current->hwFog &= ~MASK_FogZLookup;
  62          break;
  63       case GL_FRAGMENT_DEPTH_EXT:
  64          current->hwFog |= MASK_FogZLookup;
  65          break;
  66       }
  67       if (current->hwFog != prev->hwFog) {
  68          prev->hwFog = current->hwFog;
  69          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  70       }
  71       break;
  72    case GL_FOG_MODE:
  73       current->hwFog &= ~MASK_FogMode;
  74       switch (ctx->Fog.Mode)
  75       {
  76       case GL_LINEAR:
  77          current->hwFog |= FOGMODE_LINEAR;
  78          break;
  79       case GL_EXP:
  80          current->hwFog |= FOGMODE_EXP;
  81          break;
  82       case GL_EXP2:
  83          current->hwFog |= FOGMODE_EXP2;
  84          break;
  85       }
  86       if (current->hwFog != prev->hwFog) {
  87          prev->hwFog = current->hwFog;
  88          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  89       }
  90       break;
  91    case GL_FOG_DENSITY:
  92       current->hwFogDensity = convertFtToFogFt( ctx->Fog.Density );
  93       if (current->hwFogDensity != prev->hwFogDensity) {
  94          prev->hwFogDensity = current->hwFogDensity;
  95          smesa->GlobalFlag |= GFLAG_FOGSETTING;
  96       }
  97       break;
  98    case GL_FOG_START:
  99    case GL_FOG_END:
 100       fArg = 1.0 / (ctx->Fog.End - ctx->Fog.Start);
 101       current->hwFogInverse = doFPtoFixedNoRound( fArg, 10 );
 102       if (pname == GL_FOG_END)
 103       {
 104          if (smesa->Chipset == PCI_CHIP_SIS300)
 105             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 10 );
 106          else
 107             current->hwFogFar = doFPtoFixedNoRound( ctx->Fog.End, 6 );
 108       }
 109       if (current->hwFogFar != prev->hwFogFar ||
 110           current->hwFogInverse != prev->hwFogInverse)
 111       {
 112          prev->hwFogFar = current->hwFogFar;
 113          prev->hwFogInverse = current->hwFogInverse;
 114          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 115       }
 116       break;
 117    case GL_FOG_INDEX:
 118       /* TODO */
 119       break;
 120    case GL_FOG_COLOR:
 121       fogColor  = FLOAT_TO_UBYTE( ctx->Fog.Color[0] ) << 16;
 122       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[1] ) << 8;
 123       fogColor |= FLOAT_TO_UBYTE( ctx->Fog.Color[2] );
 124       current->hwFog &= 0xff000000;
 125       current->hwFog |= fogColor;
 126       if (current->hwFog != prev->hwFog) {
 127           prev->hwFog = current->hwFog;
 128          smesa->GlobalFlag |= GFLAG_FOGSETTING;
 129       }
 130       break;
 131    }
 132 }
 133
 134 static GLint
 135 doFPtoFixedNoRound( GLfloat dwInValue, int nFraction )
 136 {
 137    GLint dwMantissa;
 138    int nTemp;
 139    union { int i; float f; } u;
 140    GLint val;
 141
 142    u.f = dwInValue;
 143    val = u.i;
 144
 145    if (val == 0)
 146       return 0;
 147    nTemp = (int) (val & 0x7F800000) >> 23;
 148    nTemp = nTemp - 127 + nFraction - 23;
 149    dwMantissa = (val & 0x007FFFFF) | 0x00800000;
 150
 151    if (nTemp < -25)
 152        return 0;
 153    if (nTemp > 0)
 154       dwMantissa <<= nTemp;
 155    else {
 156       nTemp = -nTemp;
 157       dwMantissa >>= nTemp;
 158    }
 159    if (val & 0x80000000)
 160       dwMantissa = ~dwMantissa + 1;
 161    return dwMantissa;
 162 }
 163
 164 /* s[8].23->s[7].10 */
 165 static GLint
 166 convertFtToFogFt( GLfloat dwInValue )
 167 {
 168    GLint dwMantissa, dwExp;
 169    GLint dwRet;
 170    union { int i; float f; } u;
 171    GLint val;
 172
 173    u.f = dwInValue;
 174    val = u.i;
 175
 176    if (val == 0)
 177       return 0;
 178
 179    /* ----- Standard float Format: s[8].23                          -----
 180     * -----     = (-1)^S * 2^(E      - 127) * (1 + M        / 2^23) -----
 181     * -----     = (-1)^S * 2^((E-63) -  64) * (1 + (M/2^13) / 2^10) -----
 182     * ----- Density float Format:  s[7].10                          -----
 183     * -----     New Exponential = E - 63                            -----
 184     * -----     New Mantissa    = M / 2^13                          -----
 185     * -----                                                         -----
 186     */
 187
 188    dwExp = (val & 0x7F800000) >> 23;
 189    dwExp -= 63;
 190
 191    if (dwExp < 0)
 192       return 0;
 193
 194    if (dwExp <= 0x7F)
 195       dwMantissa = (val & 0x007FFFFF) >> (23 - 10);
 196    else {
 197       /* ----- To Return +Max(or -Max) ----- */
 198       dwExp = 0x7F;
 199       dwMantissa = 0x3FF;
 200    }
 201
 202    dwRet = (val & 0x80000000) >> (31 - 17);  /* Shift Sign Bit */
 203
 204    dwRet |= (dwExp << 10) | dwMantissa;
 205
 206    return dwRet;
 207 }