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