-/**********************************************************************/
-/***** 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);
- if (ctx->_ShineTable[side])
- ctx->_ShineTable[side]->refcount--;
- ctx->_ShineTable[side] = NULL;
-}
-
-
-static void
-validate_shine_table( GLcontext *ctx, GLuint side, GLfloat shininess )
-{
- struct gl_shine_tab *list = ctx->_ShineTabList;
- struct gl_shine_tab *s;
-
- ASSERT(side < 2);
-
- foreach(s, list)
- if ( s->shininess == shininess )
- break;
-
- if (s == list) {
- GLint j;
- GLfloat *m;
-
- foreach(s, list)
- if (s->refcount == 0)
- break;
-
- m = s->tab;
- m[0] = 0.0;
- if (shininess == 0.0) {
- for (j = 1 ; j <= SHINE_TABLE_SIZE ; j++)
- m[j] = 1.0;
- }
- else {
- for (j = 1 ; j < SHINE_TABLE_SIZE ; j++) {
- GLdouble t, x = j / (GLfloat) (SHINE_TABLE_SIZE - 1);
- if (x < 0.005) /* underflow check */
- x = 0.005;
- t = _mesa_pow(x, shininess);
- if (t > 1e-20)
- m[j] = (GLfloat) t;
- else
- m[j] = 0.0;
- }
- m[SHINE_TABLE_SIZE] = 1.0;
- }
-
- s->shininess = shininess;
- }
-
- if (ctx->_ShineTable[side])
- ctx->_ShineTable[side]->refcount--;
-
- ctx->_ShineTable[side] = s;
- move_to_tail( list, s );
- s->refcount++;
-}
-
-
-void
-_mesa_validate_all_lighting_tables( GLcontext *ctx )
-{
- GLuint i;
- GLfloat shininess;
-
- shininess = ctx->Light.Material.Attrib[MAT_ATTRIB_FRONT_SHININESS][0];
- if (!ctx->_ShineTable[0] || ctx->_ShineTable[0]->shininess != shininess)
- validate_shine_table( ctx, 0, shininess );
-
- shininess = ctx->Light.Material.Attrib[MAT_ATTRIB_BACK_SHININESS][0];
- if (!ctx->_ShineTable[1] || ctx->_ShineTable[1]->shininess != shininess)
- validate_shine_table( ctx, 1, shininess );
-
- for (i = 0; i < ctx->Const.MaxLights; i++)
- if (ctx->Light.Light[i]._SpotExpTable[0][0] == -1)
- validate_spot_exp_table( &ctx->Light.Light[i] );
-}
-
-