CCEffectBloom - Fix intensity math

The intensity value needs to multiply all instances of the source term in the screen
blending equation. Otherwise, even when intensity is zero, the source term is still
contributing to the final result which is not what we want.

Author: Thayer J Andrews

cocos2d/CCEffectBloom.m

@@ -105,7 +105,7 @@ -(void)setLuminanceThreshold:(float)luminanceThreshold
 -(void)setIntensity:(float)intensity
 {
     _intensity = clampf(intensity, 0.0f, 1.0f);
-    _transformedIntensity = 1.0f - _intensity;
+    _transformedIntensity = _intensity;
 }
 
 -(void)setBlurRadius:(NSUInteger)blurRadius
@@ -214,7 +214,7 @@ -(void)buildFragmentFunctions
     // Choose one?
     // TODO: try using min(src, dst) to create a gloomEffect
     // NSString* additiveBlending =  @"src + dst";
-    NSString* screenBlending = @"(src + dst) - ((src * dst) * u_intensity)";
+    NSString* screenBlending = @"(src * u_intensity + dst) - ((src * dst) * u_intensity)";
 
     [shaderString appendFormat:@"\
      return %@;\n", screenBlending];