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#version 410
out vec4 FragColor;
in vec3 WorldPos;
in vec3 Normal;
in vec2 TexCoords;
struct PointLight {
vec3 position;
vec3 color;
};
// --- Uniforms
uniform vec3 viewPos;
// Lights data
#define NUM_POINT_LIGHTS 4
uniform PointLight pointLights[NUM_POINT_LIGHTS];
// Material properties
uniform vec3 albedo;
uniform float metallic;
uniform float roughness;
uniform float ao;
// Forward declarations
vec3 fresnelSchlick(float cosTheta, vec3 F0);
float DistributionGGX(vec3 N, vec3 H, float roughness);
float GeometrySchlickGGX(float NdotV, float roughness);
float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness);
void main() {
vec3 norm = normalize(Normal);
vec3 viewDir = normalize(viewPos - WorldPos);
vec3 radiance = vec3(0.0); // denoted L in the radiance equation
for (int i = 0; i < 4; i++) {
vec3 lightVec = normalize(pointLights[i].position - WorldPos);
vec3 halfway = normalize(Normal + lightVec);
float distance = length(pointLights[i].position - WorldPos);
float attenuation = 1.0 / (distance * distance);
vec3 radiance = pointLights[i].color * attenuation;
vec3 F0 = vec3(0.04);
F0 = mix(F0, albedo, metallic);
vec3 F = fresnelSchlick(max(dot(halfway, lightVec), 0.0), F0);
}
}
/* The below are from https://learnopengl.com/PBR/Lighting */
vec3 fresnelSchlick(float cosTheta, vec3 F0) {
return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
}
float DistributionGGX(vec3 N, vec3 H, float roughness) {
float a = roughness*roughness;
float a2 = a*a;
float NdotH = max(dot(N, H), 0.0);
float NdotH2 = NdotH*NdotH;
float num = a2;
float denom = (NdotH2 * (a2 - 1.0) + 1.0);
denom = PI * denom * denom;
return num / denom;
}
float GeometrySchlickGGX(float NdotV, float roughness)
{
float r = (roughness + 1.0);
float k = (r*r) / 8.0;
float num = NdotV;
float denom = NdotV * (1.0 - k) + k;
return num / denom;
}
float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
{
float NdotV = max(dot(N, V), 0.0);
float NdotL = max(dot(N, L), 0.0);
float ggx2 = GeometrySchlickGGX(NdotV, roughness);
float ggx1 = GeometrySchlickGGX(NdotL, roughness);
return ggx1 * ggx2;
}
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