//Gravitational lensing effect. Edited from https://unionassets.com/blog/the-effect-of-the-gravitational-lens-195 to be Clyde based (based on what)

uniform sampler2D SCREEN_TEXTURE;
uniform highp vec2 positionInput;
uniform highp vec2 renderScale;
uniform highp float falloff;
uniform highp float intensity;



void fragment() {
	highp float distanceToCenter = length((FRAGCOORD.xy - positionInput) / renderScale);

	highp vec2 finalCoords = FRAGCOORD.xy - positionInput;
	highp float deformation = (pow(intensity, 2.0)*500.0) / pow(distanceToCenter, pow(falloff, 0.5));
	if(deformation > 0.8) //Edit this for inward effect
		deformation = pow(deformation, 0.3);
	if(deformation > 0.001){
		finalCoords *= 1.0-deformation; //Change this to 1+deformation for inward effect
		finalCoords += positionInput;
		//float darkenCircleSize = 600; //Calculate optional darkening effect (darker the closer we are to the center of the singularity)
		//float alph = (distanceToCenter-30)/(darkenCircleSize-30);
		//float darkening = 0.9-(alph*0.9);

		//Darkening effect optional (Darker the closer you are to the center)
		//COLOR = mix(texture(SCREEN_TEXTURE, finalCoords*SCREEN_PIXEL_SIZE), vec4(0.0, 0.0, 0.0, 1.0), darkening);
		COLOR = zTextureSpec(SCREEN_TEXTURE, finalCoords*SCREEN_PIXEL_SIZE);
	}
	else{
		COLOR = zTextureSpec(SCREEN_TEXTURE, FRAGCOORD.xy*SCREEN_PIXEL_SIZE);
	}

}