CCEffectLighting - Directional light support

For point lights we compute the light vector from each vertex position to the light position
and interpolate this across the sprite. For directional lights we set the light vector to be the
inverse of the light's direction (because light direction comes "from" the light but we want
a vector "to" the light). This is the same for all vertices so the direction is constant across
the sprite (and therefore independent of light position).

Author: Thayer J Andrews

cocos2d/CCEffectLighting.m

@@ -167,7 +167,15 @@ -(void)buildRenderPasses
             GLKMatrix4 lightNodeToEffectNode = CCEffectUtilsTransformFromNodeToNode(light, pass.node, nil);
 
             // Compute the light's position in the effect node's coordinate system.
-            GLKVector4 lightPosition = GLKMatrix4MultiplyVector4(lightNodeToEffectNode, GLKVector4Make(light.anchorPointInPoints.x, light.anchorPointInPoints.y, 500.0f, 1.0f));
+            GLKVector4 lightVector = GLKVector4Make(0.0f, 0.0f, 0.0f, 0.0f);
+            if (light.type == CCLightNodeDirectional)
+            {
+                lightVector = GLKMatrix4MultiplyVector4(lightNodeToEffectNode, GLKVector4Make(0.0f, 1.0f, 1.0f, 0.0f));
+            }
+            else
+            {
+                lightVector = GLKMatrix4MultiplyVector4(lightNodeToEffectNode, GLKVector4Make(light.anchorPointInPoints.x, light.anchorPointInPoints.y, 50.0f, 1.0f));
+            }
 
             // Compute the real light color based on color and intensity.
             GLKVector4 lightColor = GLKVector4MultiplyScalar(light.color.glkVector4, light.intensity);
@@ -176,7 +184,7 @@ -(void)buildRenderPasses
             NSString *lightVectorLabel = [NSString stringWithFormat:@"u_lightVector%lu", (unsigned long)lightIndex];
 
             pass.shaderUniforms[weakSelf.uniformTranslationTable[lightColorLabel]] = [NSValue valueWithGLKVector4:lightColor];
-            pass.shaderUniforms[weakSelf.uniformTranslationTable[lightVectorLabel]] = [NSValue valueWithGLKVector4:lightPosition];
+            pass.shaderUniforms[weakSelf.uniformTranslationTable[lightVectorLabel]] = [NSValue valueWithGLKVector4:lightVector];
         }
 
         pass.shaderUniforms[weakSelf.uniformTranslationTable[@"u_globalAmbientColor"]] = [NSValue valueWithGLKVector4:globalAmbientColor];