#version 330 core
out vec4 fragColor;
in vec2 uv;
uniform sampler2D normal;
uniform sampler2D light;
uniform sampler2D depthStencil;
uniform sampler2D ssaoNoise;
uniform int ssaoSamples;
layout (std140) uniform Globals {
mat4 projView;
mat4 proj;
mat4 invProj;
mat4 view;
uvec2 viewportSize;
vec4 ssaoKernels[64];
float globalTime;
float dayTime;
float gamma;
};
const vec2 noiseScale = vec2(4.0f, 4.0f);
const int kernelSize = 64;
const float radius = 0.5f;
const float bias = 0.025f;
vec3 RecoverViewWorldPos(vec2 screenPos, float depth) {
vec4 viewPos = invProj * vec4(screenPos * 2.0 - 1.0, depth * 2.0 - 1.0, 1.0);
return viewPos.xyz / viewPos.w;
}
void main() {
vec3 normal = texture(normal, uv).xyz;
vec3 fragPos = RecoverViewWorldPos(uv, texture(depthStencil, uv).r);
vec2 noiseUv = uv * viewportSize / noiseScale;
vec3 randomVec = texture(ssaoNoise, noiseUv).xyz;
vec3 tangent = normalize(randomVec - normal * dot(randomVec, normal));
vec3 bitangent = cross(normal, tangent);
mat3 TBN = mat3(tangent, bitangent, normal);
float occlusion = 0.0;
int samples = min(kernelSize, ssaoSamples);
for(int i = 0; i < samples; i++)
{
vec3 samplePos = TBN * ssaoKernels[i].xyz;
samplePos = fragPos + samplePos * radius;
vec4 offset = vec4(samplePos, 1.0);
offset = proj * offset;
offset.xyz /= offset.w;
offset.xyz = offset.xyz * 0.5 + 0.5;
float sampleDepth = RecoverViewWorldPos(offset.xy, texture(depthStencil, offset.xy).r).z;
float rangeCheck = smoothstep(0.0, 1.0, radius / abs(fragPos.z - sampleDepth));
float aoMask = texture(light, offset.xy).b;
occlusion += (sampleDepth >= samplePos.z + bias ? 1.0 : 0.0) * rangeCheck * aoMask;
}
occlusion = 1.0f - (occlusion / samples);
fragColor = vec4(vec3(occlusion), 1.0f);
}
