light.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

         break;
      default:
         /* Error will be caught later in gl_LightModelfv */
         ;
   }
   _mesa_LightModelfv( pname, fparam );
}


void GLAPIENTRY
_mesa_LightModeli( GLenum pname, GLint param )
{
   _mesa_LightModeliv( pname, &param );
}


void GLAPIENTRY
_mesa_LightModelf( GLenum pname, GLfloat param )
{
   _mesa_LightModelfv( pname, &param );
}



/********** MATERIAL **********/


/*
 * Given a face and pname value (ala glColorMaterial), compute a bitmask
 * of the targeted material values.
 */
GLuint
_mesa_material_bitmask( GLcontext *ctx, GLenum face, GLenum pname,
                        GLuint legal, const char *where )
{
   GLuint bitmask = 0;

   /* Make a bitmask indicating what material attribute(s) we're updating */
   switch (pname) {
      case GL_EMISSION:
         bitmask |= MAT_BIT_FRONT_EMISSION | MAT_BIT_BACK_EMISSION;
         break;
      case GL_AMBIENT:
         bitmask |= MAT_BIT_FRONT_AMBIENT | MAT_BIT_BACK_AMBIENT;
         break;
      case GL_DIFFUSE:
         bitmask |= MAT_BIT_FRONT_DIFFUSE | MAT_BIT_BACK_DIFFUSE;
         break;
      case GL_SPECULAR:
         bitmask |= MAT_BIT_FRONT_SPECULAR | MAT_BIT_BACK_SPECULAR;
         break;
      case GL_SHININESS:
         bitmask |= MAT_BIT_FRONT_SHININESS | MAT_BIT_BACK_SHININESS;
         break;
      case GL_AMBIENT_AND_DIFFUSE:
         bitmask |= MAT_BIT_FRONT_AMBIENT | MAT_BIT_BACK_AMBIENT;
         bitmask |= MAT_BIT_FRONT_DIFFUSE | MAT_BIT_BACK_DIFFUSE;
         break;
      case GL_COLOR_INDEXES:
         bitmask |= MAT_BIT_FRONT_INDEXES  | MAT_BIT_BACK_INDEXES;
         break;
      default:
         _mesa_error( ctx, GL_INVALID_ENUM, where );
         return 0;
   }

   if (face==GL_FRONT) {
      bitmask &= FRONT_MATERIAL_BITS;
   }
   else if (face==GL_BACK) {
      bitmask &= BACK_MATERIAL_BITS;
   }
   else if (face != GL_FRONT_AND_BACK) {
      _mesa_error( ctx, GL_INVALID_ENUM, where );
      return 0;
   }

   if (bitmask & ~legal) {
      _mesa_error( ctx, GL_INVALID_ENUM, where );
      return 0;
   }

   return bitmask;
}



/* Perform a straight copy between materials.
 */
void
_mesa_copy_materials( struct gl_material *dst,
                      const struct gl_material *src,
                      GLuint bitmask )
{
   int i;

   for (i = 0 ; i < MAT_ATTRIB_MAX ; i++) 
      if (bitmask & (1<<i))
	 COPY_4FV( dst->Attrib[i], src->Attrib[i] );
}



/* Update derived values following a change in ctx->Light.Material
 */
void
_mesa_update_material( GLcontext *ctx, GLuint bitmask )
{
   struct gl_light *light, *list = &ctx->Light.EnabledList;
   GLfloat (*mat)[4] = ctx->Light.Material.Attrib;

   if (MESA_VERBOSE&VERBOSE_IMMEDIATE) 
      _mesa_debug(ctx, "_mesa_update_material, mask 0x%x\n", bitmask);

   if (!bitmask)
      return;

   /* update material ambience */
   if (bitmask & MAT_BIT_FRONT_AMBIENT) {
      foreach (light, list) {
         SCALE_3V( light->_MatAmbient[0], light->Ambient, 
		   mat[MAT_ATTRIB_FRONT_AMBIENT]);
      }
   }

   if (bitmask & MAT_BIT_BACK_AMBIENT) {
      foreach (light, list) {
         SCALE_3V( light->_MatAmbient[1], light->Ambient, 
		   mat[MAT_ATTRIB_BACK_AMBIENT]);
      }
   }

   /* update BaseColor = emission + scene's ambience * material's ambience */
   if (bitmask & (MAT_BIT_FRONT_EMISSION | MAT_BIT_FRONT_AMBIENT)) {
      COPY_3V( ctx->Light._BaseColor[0], mat[MAT_ATTRIB_FRONT_EMISSION] );
      ACC_SCALE_3V( ctx->Light._BaseColor[0], mat[MAT_ATTRIB_FRONT_AMBIENT],
		    ctx->Light.Model.Ambient );
   }

   if (bitmask & (MAT_BIT_BACK_EMISSION | MAT_BIT_BACK_AMBIENT)) {
      COPY_3V( ctx->Light._BaseColor[1], mat[MAT_ATTRIB_BACK_EMISSION] );
      ACC_SCALE_3V( ctx->Light._BaseColor[1], mat[MAT_ATTRIB_BACK_AMBIENT],
		    ctx->Light.Model.Ambient );
   }

   /* update material diffuse values */
   if (bitmask & MAT_BIT_FRONT_DIFFUSE) {
      foreach (light, list) {
	 SCALE_3V( light->_MatDiffuse[0], light->Diffuse, 
		   mat[MAT_ATTRIB_FRONT_DIFFUSE] );
      }
   }

   if (bitmask & MAT_BIT_BACK_DIFFUSE) {
      foreach (light, list) {
	 SCALE_3V( light->_MatDiffuse[1], light->Diffuse, 
		   mat[MAT_ATTRIB_BACK_DIFFUSE] );
      }
   }

   /* update material specular values */
   if (bitmask & MAT_BIT_FRONT_SPECULAR) {
      foreach (light, list) {
	 SCALE_3V( light->_MatSpecular[0], light->Specular, 
		   mat[MAT_ATTRIB_FRONT_SPECULAR]);
      }
   }

   if (bitmask & MAT_BIT_BACK_SPECULAR) {
      foreach (light, list) {
	 SCALE_3V( light->_MatSpecular[1], light->Specular,
		   mat[MAT_ATTRIB_BACK_SPECULAR]);
      }
   }

   if (bitmask & MAT_BIT_FRONT_SHININESS) {
      _mesa_invalidate_shine_table( ctx, 0 );
   }

   if (bitmask & MAT_BIT_BACK_SHININESS) {
      _mesa_invalidate_shine_table( ctx, 1 );
   }
}


/*
 * Update the current materials from the given rgba color
 * according to the bitmask in ColorMaterialBitmask, which is
 * set by glColorMaterial().
 */
void
_mesa_update_color_material( GLcontext *ctx, const GLfloat color[4] )
{
   GLuint bitmask = ctx->Light.ColorMaterialBitmask;
   struct gl_material *mat = &ctx->Light.Material;
   int i;

   for (i = 0 ; i < MAT_ATTRIB_MAX ; i++) 
      if (bitmask & (1<<i))
	 COPY_4FV( mat->Attrib[i], color );

   _mesa_update_material( ctx, bitmask );
}


void GLAPIENTRY
_mesa_ColorMaterial( GLenum face, GLenum mode )
{
   GET_CURRENT_CONTEXT(ctx);
   GLuint bitmask;
   GLuint legal = (MAT_BIT_FRONT_EMISSION | MAT_BIT_BACK_EMISSION |
		   MAT_BIT_FRONT_SPECULAR | MAT_BIT_BACK_SPECULAR |
		   MAT_BIT_FRONT_DIFFUSE  | MAT_BIT_BACK_DIFFUSE  |
		   MAT_BIT_FRONT_AMBIENT  | MAT_BIT_BACK_AMBIENT);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (MESA_VERBOSE&VERBOSE_API)
      _mesa_debug(ctx, "glColorMaterial %s %s\n",
                  _mesa_lookup_enum_by_nr(face),
                  _mesa_lookup_enum_by_nr(mode));

   bitmask = _mesa_material_bitmask(ctx, face, mode, legal, "glColorMaterial");

   if (ctx->Light.ColorMaterialBitmask == bitmask &&
       ctx->Light.ColorMaterialFace == face &&
       ctx->Light.ColorMaterialMode == mode)
      return;

   FLUSH_VERTICES(ctx, _NEW_LIGHT);
   ctx->Light.ColorMaterialBitmask = bitmask;
   ctx->Light.ColorMaterialFace = face;
   ctx->Light.ColorMaterialMode = mode;

   if (ctx->Light.ColorMaterialEnabled) {
      FLUSH_CURRENT( ctx, 0 );
      _mesa_update_color_material(ctx,ctx->Current.Attrib[VERT_ATTRIB_COLOR0]);
   }

   if (ctx->Driver.ColorMaterial)
      (*ctx->Driver.ColorMaterial)( ctx, face, mode );
}


void GLAPIENTRY
_mesa_GetMaterialfv( GLenum face, GLenum pname, GLfloat *params )
{
   GET_CURRENT_CONTEXT(ctx);
   GLuint f;
   GLfloat (*mat)[4] = ctx->Light.Material.Attrib;
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* update materials */

   FLUSH_CURRENT(ctx, 0); /* update ctx->Light.Material from vertex buffer */

   if (face==GL_FRONT) {
      f = 0;
   }
   else if (face==GL_BACK) {
      f = 1;
   }
   else {
      _mesa_error( ctx, GL_INVALID_ENUM, "glGetMaterialfv(face)" );
      return;
   }

   switch (pname) {
      case GL_AMBIENT:
         COPY_4FV( params, mat[MAT_ATTRIB_AMBIENT(f)] );
         break;
      case GL_DIFFUSE:
         COPY_4FV( params, mat[MAT_ATTRIB_DIFFUSE(f)] );
	 break;
      case GL_SPECULAR:
         COPY_4FV( params, mat[MAT_ATTRIB_SPECULAR(f)] );
	 break;
      case GL_EMISSION:
	 COPY_4FV( params, mat[MAT_ATTRIB_EMISSION(f)] );
	 break;
      case GL_SHININESS:
	 *params = mat[MAT_ATTRIB_SHININESS(f)][0];
	 break;
      case GL_COLOR_INDEXES:
	 params[0] = mat[MAT_ATTRIB_INDEXES(f)][0];
	 params[1] = mat[MAT_ATTRIB_INDEXES(f)][1];
	 params[2] = mat[MAT_ATTRIB_INDEXES(f)][2];
	 break;
      default:
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetMaterialfv(pname)" );
   }
}


void GLAPIENTRY
_mesa_GetMaterialiv( GLenum face, GLenum pname, GLint *params )
{
   GET_CURRENT_CONTEXT(ctx);
   GLuint f;
   GLfloat (*mat)[4] = ctx->Light.Material.Attrib;
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* update materials */

   FLUSH_CURRENT(ctx, 0); /* update ctx->Light.Material from vertex buffer */

   if (face==GL_FRONT) {
      f = 0;
   }
   else if (face==GL_BACK) {
      f = 1;
   }
   else {
      _mesa_error( ctx, GL_INVALID_ENUM, "glGetMaterialiv(face)" );
      return;
   }
   switch (pname) {
      case GL_AMBIENT:
         params[0] = FLOAT_TO_INT( mat[MAT_ATTRIB_AMBIENT(f)][0] );
         params[1] = FLOAT_TO_INT( mat[MAT_ATTRIB_AMBIENT(f)][1] );
         params[2] = FLOAT_TO_INT( mat[MAT_ATTRIB_AMBIENT(f)][2] );
         params[3] = FLOAT_TO_INT( mat[MAT_ATTRIB_AMBIENT(f)][3] );
         break;
      case GL_DIFFUSE:
         params[0] = FLOAT_TO_INT( mat[MAT_ATTRIB_DIFFUSE(f)][0] );
         params[1] = FLOAT_TO_INT( mat[MAT_ATTRIB_DIFFUSE(f)][1] );
         params[2] = FLOAT_TO_INT( mat[MAT_ATTRIB_DIFFUSE(f)][2] );
         params[3] = FLOAT_TO_INT( mat[MAT_ATTRIB_DIFFUSE(f)][3] );
	 break;
      case GL_SPECULAR:
         params[0] = FLOAT_TO_INT( mat[MAT_ATTRIB_SPECULAR(f)][0] );
         params[1] = FLOAT_TO_INT( mat[MAT_ATTRIB_SPECULAR(f)][1] );
         params[2] = FLOAT_TO_INT( mat[MAT_ATTRIB_SPECULAR(f)][2] );
         params[3] = FLOAT_TO_INT( mat[MAT_ATTRIB_SPECULAR(f)][3] );
	 break;
      case GL_EMISSION:
         params[0] = FLOAT_TO_INT( mat[MAT_ATTRIB_EMISSION(f)][0] );
         params[1] = FLOAT_TO_INT( mat[MAT_ATTRIB_EMISSION(f)][1] );
         params[2] = FLOAT_TO_INT( mat[MAT_ATTRIB_EMISSION(f)][2] );
         params[3] = FLOAT_TO_INT( mat[MAT_ATTRIB_EMISSION(f)][3] );
	 break;
      case GL_SHININESS:
         *params = IROUND( mat[MAT_ATTRIB_SHININESS(f)][0] );
	 break;
      case GL_COLOR_INDEXES:
	 params[0] = IROUND( mat[MAT_ATTRIB_INDEXES(f)][0] );
	 params[1] = IROUND( mat[MAT_ATTRIB_INDEXES(f)][1] );
	 params[2] = IROUND( mat[MAT_ATTRIB_INDEXES(f)][2] );
	 break;
      default:
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetMaterialfv(pname)" );
   }
}



/**********************************************************************/
/*****                  Lighting computation                      *****/
/**********************************************************************/


/*
 * Notes:
 *   When two-sided lighting is enabled we compute the color (or index)
 *   for both the front and back side of the primitive.  Then, when the
 *   orientation of the facet is later learned, we can determine which
 *   color (or index) to use for rendering.
 *
 *   KW: We now know orientation in advance and only shade for
 *       the side or sides which are actually required.
 *
 * Variables:
 *   n = normal vector
 *   V = vertex position
 *   P = light source position
 *   Pe = (0,0,0,1)
 *
 * Precomputed:
 *   IF P[3]==0 THEN
 *       // light at infinity
 *       IF local_viewer THEN
 *           _VP_inf_norm = unit vector from V to P      // Precompute
 *       ELSE
 *           // eye at infinity
 *           _h_inf_norm = Normalize( VP + <0,0,1> )     // Precompute
 *       ENDIF
 *   ENDIF
 *
 * Functions:
 *   Normalize( v ) = normalized vector v
 *   Magnitude( v ) = length of vector v
 */



/*
 * Whenever the spotlight exponent for a light changes we must call
 * this function to recompute the exponent lookup table.
 */
void
_mesa_invalidate_spot_exp_table( struct gl_light *l )
{
   l->_SpotExpTable[0][0] = -1;
}


static void
validate_spot_exp_table( struct gl_light *l )
{
   GLint i;
   GLdouble exponent = l->SpotExponent;
   GLdouble tmp = 0;
   GLint clamp = 0;

   l->_SpotExpTable[0][0] = 0.0;

   for (i = EXP_TABLE_SIZE - 1; i > 0 ;i--) {
      if (clamp == 0) {
	 tmp = _mesa_pow(i / (GLdouble) (EXP_TABLE_SIZE - 1), exponent);
	 if (tmp < FLT_MIN * 100.0) {
	    tmp = 0.0;
	    clamp = 1;
	 }
      }
      l->_SpotExpTable[i][0] = (GLfloat) tmp;
   }
   for (i = 0; i < EXP_TABLE_SIZE - 1; i++) {
      l->_SpotExpTable[i][1] = (l->_SpotExpTable[i+1][0] -
				l->_SpotExpTable[i][0]);
   }
   l->_SpotExpTable[EXP_TABLE_SIZE-1][1] = 0.0;
}



/* Calculate a new shine table.  Doing this here saves a branch in
 * lighting, and the cost of doing it early may be partially offset
 * by keeping a MRU cache of shine tables for various shine values.
 */
void
_mesa_invalidate_shine_table( GLcontext *ctx, GLuint side )
{
   ASSERT(side < 2);