+
+#define LIGHT_STAGE_DATA(stage) ((struct light_stage_data *)(stage->privatePtr))
+
+
+
+/**********************************************************************/
+/***** 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
+ */
+
+
+
+static void
+validate_shine_table( struct gl_context *ctx, GLuint side, GLfloat shininess )
+{
+ TNLcontext *tnl = TNL_CONTEXT(ctx);
+ struct tnl_shine_tab *list = tnl->_ShineTabList;
+ struct tnl_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 = 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 (tnl->_ShineTable[side])
+ tnl->_ShineTable[side]->refcount--;
+
+ tnl->_ShineTable[side] = s;
+ move_to_tail( list, s );
+ s->refcount++;
+}
+
+
+void
+_tnl_validate_shine_tables( struct gl_context *ctx )
+{
+ TNLcontext *tnl = TNL_CONTEXT(ctx);
+ GLfloat shininess;
+
+ shininess = ctx->Light.Material.Attrib[MAT_ATTRIB_FRONT_SHININESS][0];
+ if (!tnl->_ShineTable[0] || tnl->_ShineTable[0]->shininess != shininess)
+ validate_shine_table( ctx, 0, shininess );
+
+ shininess = ctx->Light.Material.Attrib[MAT_ATTRIB_BACK_SHININESS][0];
+ if (!tnl->_ShineTable[1] || tnl->_ShineTable[1]->shininess != shininess)
+ validate_shine_table( ctx, 1, shininess );
+}
+
+
+/**
+ * In the case of colormaterial, the effected material attributes
+ * should already have been bound to point to the incoming color data,
+ * prior to running the pipeline.
+ * This function copies the vertex's color to the material attributes
+ * which are tracking glColor.
+ * It's called per-vertex in the lighting loop.
+ */
+static void
+update_materials(struct gl_context *ctx, struct light_stage_data *store)
+{
+ GLuint i;
+
+ for (i = 0 ; i < store->mat_count ; i++) {
+ /* update the material */
+ COPY_CLEAN_4V(store->mat[i].current, store->mat[i].size, store->mat[i].ptr);
+ /* increment src vertex color pointer */
+ STRIDE_F(store->mat[i].ptr, store->mat[i].stride);
+ }
+
+ /* recompute derived light/material values */
+ _mesa_update_material( ctx, store->mat_bitmask );
+ /* XXX we should only call this if we're tracking/changing the specular
+ * exponent.
+ */
+ _tnl_validate_shine_tables( ctx );
+}
+
+
+/**
+ * Prepare things prior to running the lighting stage.
+ * Return number of material attributes which will track vertex color.
+ */
+static GLuint
+prepare_materials(struct gl_context *ctx,
+ struct vertex_buffer *VB, struct light_stage_data *store)
+{
+ GLuint i;
+
+ store->mat_count = 0;
+ store->mat_bitmask = 0;
+
+ /* Examine the _ColorMaterialBitmask to determine which materials
+ * track vertex color. Override the material attribute's pointer
+ * with the color pointer for each one.
+ */
+ if (ctx->Light.ColorMaterialEnabled) {
+ const GLuint bitmask = ctx->Light._ColorMaterialBitmask;
+ for (i = 0 ; i < MAT_ATTRIB_MAX ; i++)
+ if (bitmask & (1<<i))
+ VB->AttribPtr[_TNL_ATTRIB_MAT_FRONT_AMBIENT + i] = VB->AttribPtr[_TNL_ATTRIB_COLOR0];
+ }
+
+ /* Now, for each material attribute that's tracking vertex color, save
+ * some values (ptr, stride, size, current) that we'll need in
+ * update_materials(), above, that'll actually copy the vertex color to
+ * the material attribute(s).
+ */
+ for (i = _TNL_FIRST_MAT; i <= _TNL_LAST_MAT; i++) {
+ if (VB->AttribPtr[i]->stride) {
+ const GLuint j = store->mat_count++;
+ const GLuint attr = i - _TNL_ATTRIB_MAT_FRONT_AMBIENT;
+ store->mat[j].ptr = VB->AttribPtr[i]->start;
+ store->mat[j].stride = VB->AttribPtr[i]->stride;
+ store->mat[j].size = VB->AttribPtr[i]->size;
+ store->mat[j].current = ctx->Light.Material.Attrib[attr];
+ store->mat_bitmask |= (1<<attr);
+ }
+ }
+
+ /* FIXME: Is this already done?
+ */
+ _mesa_update_material( ctx, ~0 );
+
+ _tnl_validate_shine_tables( ctx );
+
+ return store->mat_count;
+}
+
+/*
+ * Compute dp ^ SpecularExponent.
+ * Lerp between adjacent values in the f(x) lookup table, giving a
+ * continuous function, with adequate overall accuracy. (Though still
+ * pretty good compared to a straight lookup).
+ */
+static inline GLfloat
+lookup_shininess(const struct gl_context *ctx, GLuint face, GLfloat dp)
+{
+ TNLcontext *tnl = TNL_CONTEXT(ctx);
+ const struct tnl_shine_tab *tab = tnl->_ShineTable[face];
+ float f = dp * (SHINE_TABLE_SIZE - 1);
+ int k = (int) f;
+ if (k < 0 /* gcc may cast an overflow float value to negative int value */
+ || k > SHINE_TABLE_SIZE - 2)
+ return powf(dp, tab->shininess);
+ else
+ return tab->tab[k] + (f - k) * (tab->tab[k+1] - tab->tab[k]);
+}