ssao.lua

/*
This software is in the public domain. Where that dedication is not recognized,
you are granted a perpetual, irrevokable license to copy and modify this file
as you see fit.
*/

float GetDepth(sampler2D tex_heightmap, vec2 UV ) {
	return texture2D(tex_heightmap, UV).r;	
}

vec4 effect(vec4 colour, sampler2D tex_heightmap, vec2 UV, vec2 pixel_UVs) {
	float Depth = GetDepth(tex_heightmap, UV);
	
	float WidthOffset = 1.0 / (love_ScreenSize.x / love_ScreenSize.y * 640.0);
	float HeightOffset = 1.0 / 640.0;

	float OcclusionCapacity = 1.0;

	float Occlusion = 0.0;
	
	float Multiplier = 6.0;

	float DepthTolerance = 0.1;
	
	float Steps = 4.0 * 8.0;
	
	float CurrentDepth;
	for(int I = 0; I < Steps / 4.0; I++)
	{
		CurrentDepth = GetDepth(tex_heightmap, vec2(UV.x + WidthOffset,UV.y + HeightOffset));
		Occlusion += min(OcclusionCapacity, max(0.0,Depth - CurrentDepth - DepthTolerance) * Multiplier);

		CurrentDepth = GetDepth(tex_heightmap, vec2(UV.x - WidthOffset,UV.y + HeightOffset));
		Occlusion += min(OcclusionCapacity, max(0.0,Depth - CurrentDepth - DepthTolerance) * Multiplier);

		CurrentDepth = GetDepth(tex_heightmap, vec2(UV.x + WidthOffset,UV.y - HeightOffset));
		Occlusion += min(OcclusionCapacity, max(0.0,Depth - CurrentDepth - DepthTolerance) * Multiplier);

		CurrentDepth = GetDepth(tex_heightmap, vec2(UV.x - WidthOffset,UV.y - HeightOffset));
		Occlusion += min(OcclusionCapacity, max(0.0,Depth - CurrentDepth - DepthTolerance) * Multiplier);
		
		WidthOffset *= 1.5;
		HeightOffset *= 1.5;
		Multiplier = Multiplier / 1.5;
	}
	
	Occlusion /= Steps;
	Occlusion = 1.0 - Occlusion;
	
	//return Albedo - Occlusion;
	return vec4(Occlusion, Occlusion, Occlusion, 1.0);
}