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      1 /*
      2  * Mesa 3-D graphics library
      3  *
      4  * Copyright (C) 1999-2003  Brian Paul   All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the "Software"),
      8  * to deal in the Software without restriction, including without limitation
      9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     10  * and/or sell copies of the Software, and to permit persons to whom the
     11  * Software is furnished to do so, subject to the following conditions:
     12  *
     13  * The above copyright notice and this permission notice shall be included
     14  * in all copies or substantial portions of the Software.
     15  *
     16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
     20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     22  * OTHER DEALINGS IN THE SOFTWARE.
     23  */
     24 
     25 
     26 #include "glheader.h"
     27 #include "context.h"
     28 #include "fog.h"
     29 #include "macros.h"
     30 #include "mtypes.h"
     31 
     32 
     33 
     34 void GLAPIENTRY
     35 _mesa_Fogf(GLenum pname, GLfloat param)
     36 {
     37    GLfloat fparam[4];
     38    fparam[0] = param;
     39    fparam[1] = fparam[2] = fparam[3] = 0.0F;
     40    _mesa_Fogfv(pname, fparam);
     41 }
     42 
     43 
     44 void GLAPIENTRY
     45 _mesa_Fogi(GLenum pname, GLint param )
     46 {
     47    GLfloat fparam[4];
     48    fparam[0] = (GLfloat) param;
     49    fparam[1] = fparam[2] = fparam[3] = 0.0F;
     50    _mesa_Fogfv(pname, fparam);
     51 }
     52 
     53 
     54 void GLAPIENTRY
     55 _mesa_Fogiv(GLenum pname, const GLint *params )
     56 {
     57    GLfloat p[4];
     58    switch (pname) {
     59       case GL_FOG_MODE:
     60       case GL_FOG_DENSITY:
     61       case GL_FOG_START:
     62       case GL_FOG_END:
     63       case GL_FOG_INDEX:
     64       case GL_FOG_COORDINATE_SOURCE_EXT:
     65 	 p[0] = (GLfloat) *params;
     66 	 break;
     67       case GL_FOG_COLOR:
     68 	 p[0] = INT_TO_FLOAT( params[0] );
     69 	 p[1] = INT_TO_FLOAT( params[1] );
     70 	 p[2] = INT_TO_FLOAT( params[2] );
     71 	 p[3] = INT_TO_FLOAT( params[3] );
     72 	 break;
     73       default:
     74          /* Error will be caught later in _mesa_Fogfv */
     75          ASSIGN_4V(p, 0.0F, 0.0F, 0.0F, 0.0F);
     76    }
     77    _mesa_Fogfv(pname, p);
     78 }
     79 
     80 
     81 /**
     82  * Update the gl_fog_attrib::_Scale field.
     83  */
     84 static void
     85 update_fog_scale(struct gl_context *ctx)
     86 {
     87    if (ctx->Fog.End == ctx->Fog.Start)
     88       ctx->Fog._Scale = 1.0f;
     89    else
     90       ctx->Fog._Scale = 1.0f / (ctx->Fog.End - ctx->Fog.Start);
     91 }
     92 
     93 
     94 void GLAPIENTRY
     95 _mesa_Fogfv( GLenum pname, const GLfloat *params )
     96 {
     97    GET_CURRENT_CONTEXT(ctx);
     98    GLenum m;
     99 
    100    switch (pname) {
    101       case GL_FOG_MODE:
    102          m = (GLenum) (GLint) *params;
    103 	 switch (m) {
    104 	 case GL_LINEAR:
    105 	 case GL_EXP:
    106 	 case GL_EXP2:
    107 	    break;
    108 	 default:
    109 	    _mesa_error( ctx, GL_INVALID_ENUM, "glFog" );
    110             return;
    111 	 }
    112 	 if (ctx->Fog.Mode == m)
    113 	    return;
    114 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    115 	 ctx->Fog.Mode = m;
    116 	 break;
    117       case GL_FOG_DENSITY:
    118 	 if (*params<0.0F) {
    119 	    _mesa_error( ctx, GL_INVALID_VALUE, "glFog" );
    120             return;
    121 	 }
    122 	 if (ctx->Fog.Density == *params)
    123 	    return;
    124 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    125 	 ctx->Fog.Density = *params;
    126 	 break;
    127       case GL_FOG_START:
    128          if (ctx->Fog.Start == *params)
    129             return;
    130          FLUSH_VERTICES(ctx, _NEW_FOG);
    131          ctx->Fog.Start = *params;
    132          update_fog_scale(ctx);
    133          break;
    134       case GL_FOG_END:
    135          if (ctx->Fog.End == *params)
    136             return;
    137          FLUSH_VERTICES(ctx, _NEW_FOG);
    138          ctx->Fog.End = *params;
    139          update_fog_scale(ctx);
    140          break;
    141       case GL_FOG_INDEX:
    142          if (ctx->API != API_OPENGL_COMPAT)
    143             goto invalid_pname;
    144  	 if (ctx->Fog.Index == *params)
    145 	    return;
    146 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    147  	 ctx->Fog.Index = *params;
    148 	 break;
    149       case GL_FOG_COLOR:
    150 	 if (TEST_EQ_4V(ctx->Fog.Color, params))
    151 	    return;
    152 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    153 	 ctx->Fog.ColorUnclamped[0] = params[0];
    154 	 ctx->Fog.ColorUnclamped[1] = params[1];
    155 	 ctx->Fog.ColorUnclamped[2] = params[2];
    156 	 ctx->Fog.ColorUnclamped[3] = params[3];
    157 	 ctx->Fog.Color[0] = CLAMP(params[0], 0.0F, 1.0F);
    158 	 ctx->Fog.Color[1] = CLAMP(params[1], 0.0F, 1.0F);
    159 	 ctx->Fog.Color[2] = CLAMP(params[2], 0.0F, 1.0F);
    160 	 ctx->Fog.Color[3] = CLAMP(params[3], 0.0F, 1.0F);
    161          break;
    162       case GL_FOG_COORDINATE_SOURCE_EXT: {
    163 	 GLenum p = (GLenum) (GLint) *params;
    164          if (ctx->API != API_OPENGL_COMPAT ||
    165              (p != GL_FOG_COORDINATE_EXT && p != GL_FRAGMENT_DEPTH_EXT)) {
    166 	    _mesa_error(ctx, GL_INVALID_ENUM, "glFog");
    167 	    return;
    168 	 }
    169 	 if (ctx->Fog.FogCoordinateSource == p)
    170 	    return;
    171 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    172 	 ctx->Fog.FogCoordinateSource = p;
    173 	 break;
    174       }
    175       case GL_FOG_DISTANCE_MODE_NV: {
    176 	 GLenum p = (GLenum) (GLint) *params;
    177          if (ctx->API != API_OPENGL_COMPAT || !ctx->Extensions.NV_fog_distance ||
    178              (p != GL_EYE_RADIAL_NV && p != GL_EYE_PLANE && p != GL_EYE_PLANE_ABSOLUTE_NV)) {
    179 	    _mesa_error(ctx, GL_INVALID_ENUM, "glFog");
    180 	    return;
    181 	 }
    182 	 if (ctx->Fog.FogDistanceMode == p)
    183 	    return;
    184 	 FLUSH_VERTICES(ctx, _NEW_FOG);
    185 	 ctx->Fog.FogDistanceMode = p;
    186 	 break;
    187       }
    188       default:
    189          goto invalid_pname;
    190    }
    191 
    192    if (ctx->Driver.Fogfv) {
    193       ctx->Driver.Fogfv( ctx, pname, params );
    194    }
    195 
    196    return;
    197 
    198 invalid_pname:
    199    _mesa_error( ctx, GL_INVALID_ENUM, "glFog" );
    200    return;
    201 }
    202 
    203 
    204 /**********************************************************************/
    205 /*****                      Initialization                        *****/
    206 /**********************************************************************/
    207 
    208 void _mesa_init_fog( struct gl_context * ctx )
    209 {
    210    /* Fog group */
    211    ctx->Fog.Enabled = GL_FALSE;
    212    ctx->Fog.Mode = GL_EXP;
    213    ASSIGN_4V( ctx->Fog.Color, 0.0, 0.0, 0.0, 0.0 );
    214    ASSIGN_4V( ctx->Fog.ColorUnclamped, 0.0, 0.0, 0.0, 0.0 );
    215    ctx->Fog.Index = 0.0;
    216    ctx->Fog.Density = 1.0;
    217    ctx->Fog.Start = 0.0;
    218    ctx->Fog.End = 1.0;
    219    ctx->Fog.ColorSumEnabled = GL_FALSE;
    220    ctx->Fog.FogCoordinateSource = GL_FRAGMENT_DEPTH_EXT;
    221    ctx->Fog._Scale = 1.0f;
    222    ctx->Fog.FogDistanceMode = GL_EYE_PLANE_ABSOLUTE_NV;
    223 }
    224