106 lines
2.6 KiB
Forth
106 lines
2.6 KiB
Forth
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#version 460 core
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out vec4 FragColor;
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in vec2 TexCoords;
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in vec3 WorldPos;
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in vec3 Normal;
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uniform vec3 camPos;
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uniform vec3 albedo;
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uniform float metallic;
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uniform float roughness;
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uniform float ao;
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uniform vec3 lightPositions[4];
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uniform vec3 lightColors[4];
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const float PI = 3.14159265359;
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// ratio Refraction vs Reflection (F function)
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vec3 fresnelSchlick (float cosTheta, vec3 F0)
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{
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return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
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}
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// Calculate Normal distribution (D function)
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float DistributionGGX(vec3 N , vec3 H, float roughness){
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float a = roughness*roughness;
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float a2 = a*a;
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float NdotH = max(dot(N, H), 0.0);
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float NdotH2 = NdotH * NdotH;
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float num = a2;
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float denom = (NdotH2 * ( a2 - 1.0) + 1.0);
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denom = PI * denom * denom;
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return num / denom;
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}
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// G function
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float GeometrySchlickGGX(float NdotV, float roughness){
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float r = (roughness + 1.0);
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float k = (r*r) / 8.0;
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float num = NdotV;
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float denom = NdotV * (1.0 - k) + k;
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return num / denom;
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}
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float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
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{
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float NdotV = max(dot(N, V), 0.0);
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float NdotL = max(dot(N,L), 0.0);
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float ggx2 = GeometrySchlickGGX(NdotV, roughness);
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float ggx1 = GeometrySchlickGGX(NdotL, roughness);
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return ggx1 * ggx2;
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}
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void main(){
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vec3 N = normalize(Normal);
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vec3 V = normalize(camPos - WorldPos);
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vec3 F0 = vec3(0.04);
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F0 = mix(F0, albedo, metallic);
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// Calculate the light contributions of each light source
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vec3 Lo = vec3(0.0);
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for( int i = 0; i < 4; ++i)
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{
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vec3 L = normalize(lightPositions[i] - WorldPos);
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vec3 H = normalize(V + L);
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float distance = length(lightPositions[i] - WorldPos);
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float attenuation = 1.0/ (distance*distance);
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vec3 radiance = lightColors[i] * attenuation;
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float NDF = DistributionGGX(N,H, roughness);
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float G = GeometrySmith(N,V,L, roughness);
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vec3 F = fresnelSchlick(max(dot(H,V), 0.0), F0);
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vec3 kS = F;
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vec3 kD = vec3(1.0) - kS;
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kD *= 1.0 - metallic;
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vec3 numerator = NDF * G * F;
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float denominator = 4.0 * max(dot(N,V), 0.0) * max(dot(N, L), 0.0) + 0.0001;
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vec3 specular = numerator /denominator;
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float NdotL = max(dot(N,L), 0.0);
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Lo += (kD * albedo / PI + specular) * radiance * NdotL;
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}
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// Calculate the ambient term and add it
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vec3 ambient = vec3(0.03) * albedo * ao;
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vec3 color = ambient + Lo;
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// Gamma correct the result
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color = color / (color + vec3(1.0));
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color = pow(color, vec3(1.0/2.2));
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FragColor = vec4(color, 1.0);
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}
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