CCEffectLighting + CCLightNode - Initial support for point light falloff

The user can now specify a radius which is the distance at which a light's intensity has fallen
off to 0%. Currently the falloff is linear and is disabled when the radius is set to values <= 0.0.

Author: Thayer J Andrews

cocos2d/CCEffectLighting.m

@@ -53,9 +53,16 @@ -(id)initWithLights:(NSArray *)lights
 
         for (NSUInteger lightIndex = 0; lightIndex < lights.count; lightIndex++)
         {
+            CCLightNode *light = lights[lightIndex];
+
             [vertUniforms addObject:[CCEffectUniform uniform:@"vec4" name:[NSString stringWithFormat:@"u_lightVector%lu", (unsigned long)lightIndex] value:[NSValue valueWithGLKVector4:GLKVector4Make(0.0f, 0.0f, 0.0f, 1.0f)]]];
             [fragUniforms addObject:[CCEffectUniform uniform:@"vec4" name:[NSString stringWithFormat:@"u_lightColor%lu", (unsigned long)lightIndex] value:[NSValue valueWithGLKVector4:GLKVector4Make(1.0f, 1.0f, 1.0f, 1.0f)]]];
 
+            if (light.type != CCLightDirectional)
+            {
+                [fragUniforms addObject:[CCEffectUniform uniform:@"float" name:[NSString stringWithFormat:@"u_lightFalloff%lu", (unsigned long)lightIndex] value:[NSNumber numberWithFloat:1.0f]]];
+            }
+            
             [varyings addObject:[CCEffectVarying varying:@"vec4" name:[NSString stringWithFormat:@"v_tangentSpaceLightDir%lu", (unsigned long)lightIndex]]];
         }
 
@@ -102,12 +109,28 @@ +(NSMutableArray *)buildFragmentFunctionsWithLights:(NSArray*)lights
                                      {
                                          return vec4(0,0,0,0);
                                      }
+                                     
+                                     vec4 lightColor;
+                                     vec4 tangentSpaceLightDir;
                                      vec4 resultColor = u_globalAmbientColor;
+                                     float lightDist;
                                      )];
 
     for (NSUInteger lightIndex = 0; lightIndex < lights.count; lightIndex++)
     {
-        [effectBody appendFormat:@"resultColor += u_lightColor%lu * dot(tangentSpaceNormal, v_tangentSpaceLightDir%lu);\n", (unsigned long)lightIndex, (unsigned long)lightIndex];
+        CCLightNode *light = lights[lightIndex];
+        if (light.type == CCLightDirectional)
+        {
+            [effectBody appendFormat:@"tangentSpaceLightDir = v_tangentSpaceLightDir%lu;\n", (unsigned long)lightIndex];
+            [effectBody appendFormat:@"lightColor = u_lightColor%lu;\n", (unsigned long)lightIndex];
+        }
+        else
+        {
+            [effectBody appendFormat:@"tangentSpaceLightDir = normalize(v_tangentSpaceLightDir%lu);\n", (unsigned long)lightIndex];
+            [effectBody appendFormat:@"lightDist = length(v_tangentSpaceLightDir%lu);\n", (unsigned long)lightIndex];
+            [effectBody appendFormat:@"lightColor = u_lightColor%lu * max(0.0, (1.0 - lightDist * u_lightFalloff%lu));\n", (unsigned long)lightIndex, (unsigned long)lightIndex];
+        }
+        [effectBody appendFormat:@"resultColor += lightColor * max(0.0, dot(tangentSpaceNormal, tangentSpaceLightDir));\n"];
     }
     [effectBody appendString:@"return resultColor * inputValue;\n"];
 
@@ -128,7 +151,7 @@ +(NSMutableArray *)buildVertexFunctionsWithLights:(NSArray*)lights
         }
         else
         {
-            [effectBody appendFormat:@"v_tangentSpaceLightDir%lu = normalize(u_lightVector%lu - u_ndcToTangentSpace * cc_Position);", (unsigned long)lightIndex, (unsigned long)lightIndex];
+            [effectBody appendFormat:@"v_tangentSpaceLightDir%lu = u_lightVector%lu - u_ndcToTangentSpace * cc_Position;", (unsigned long)lightIndex, (unsigned long)lightIndex];
         }
     }
     [effectBody appendString:@"return cc_Position;"];
@@ -175,15 +198,19 @@ -(void)buildRenderPasses
             else
             {
                 lightVector = GLKMatrix4MultiplyVector4(lightNodeToEffectNode, GLKVector4Make(light.anchorPointInPoints.x, light.anchorPointInPoints.y, 500.0f, 1.0f));
+
+                float falloff = (light.cutoffRadius > 0.0f) ? 1.0f / light.cutoffRadius : 0.0f;
+                NSString *lightFalloffLabel = [NSString stringWithFormat:@"u_lightFalloff%lu", (unsigned long)lightIndex];
+                pass.shaderUniforms[weakSelf.uniformTranslationTable[lightFalloffLabel]] = [NSNumber numberWithFloat:falloff];
             }
 
             // Compute the real light color based on color and intensity.
             GLKVector4 lightColor = GLKVector4MultiplyScalar(light.color.glkVector4, light.intensity);
 
             NSString *lightColorLabel = [NSString stringWithFormat:@"u_lightColor%lu", (unsigned long)lightIndex];
-            NSString *lightVectorLabel = [NSString stringWithFormat:@"u_lightVector%lu", (unsigned long)lightIndex];
-            
             pass.shaderUniforms[weakSelf.uniformTranslationTable[lightColorLabel]] = [NSValue valueWithGLKVector4:lightColor];
+
+            NSString *lightVectorLabel = [NSString stringWithFormat:@"u_lightVector%lu", (unsigned long)lightIndex];
             pass.shaderUniforms[weakSelf.uniformTranslationTable[lightVectorLabel]] = [NSValue valueWithGLKVector4:lightVector];
         }
 

cocos2d/CCLightNode.h

@@ -67,6 +67,13 @@ typedef NS_ENUM(NSUInteger, CCLightType)
  */
 @property (nonatomic, assign) float ambientIntensity;
 
+/** The radius of influence of a point light. When the distance from a sprite to this light
+ *  is less than or equal to the radius, the sprite will be lit by this light. If the
+ *  distance is greater, the sprite will not be lit by this light. This distance is
+ *  measured in points. This propery has no effect on directional lights.
+ */
+@property (nonatomic, assign) float cutoffRadius;
+
 
 
 /// -----------------------------------------------------------------------

cocos2d/CCLightNode.m

@@ -26,6 +26,7 @@ -(id)initWithType:(CCLightType)type color:(CCColor *)color intensity:(float)inte
         _intensity = intensity;
         _ambientColor = ambientColor;
         _ambientIntensity = ambientIntensity;
+        _cutoffRadius = 0.0f;
     }
 
     return self;