127 lines
3.3 KiB
GLSL
127 lines
3.3 KiB
GLSL
#version 410 core
|
|
|
|
// Output color
|
|
out vec4 FragColor;
|
|
|
|
in vec3 vertexPos;
|
|
in vec3 vertexNormal;
|
|
in vec2 TexCoords;
|
|
|
|
uniform vec3 lightPos;
|
|
uniform vec3 viewPos;
|
|
|
|
// From Object Renderer
|
|
uniform vec3 ambientColor;
|
|
uniform vec3 diffuseColor;
|
|
uniform vec3 specularColor; // used as F0 (base reflectance)
|
|
|
|
uniform float ambientStrength;
|
|
uniform float specularStrength;
|
|
uniform float shininess; // mapped to roughness
|
|
uniform bool useSpecular;
|
|
|
|
uniform float opacity;
|
|
|
|
uniform sampler2D diffuseTex;
|
|
uniform bool useTexture;
|
|
|
|
#define LIGHT_COLOR vec3(1.0, 1.0, 1.0)
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Helper functions for Cook-Torrance BRDF
|
|
// ----------------------------------------------------------------------------
|
|
|
|
// Normal Distribution Function (GGX/Trowbridge-Reitz)
|
|
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 = 3.14159265 * denom * denom;
|
|
|
|
return num / denom;
|
|
}
|
|
|
|
// Geometry function (Schlick-GGX)
|
|
float GeometrySchlickGGX(float NdotV, float roughness)
|
|
{
|
|
float r = (roughness + 1.0);
|
|
float k = (r * r) / 8.0; // remapped for direct lighting
|
|
|
|
float num = NdotV;
|
|
float denom = NdotV * (1.0 - k) + k;
|
|
|
|
return num / denom;
|
|
}
|
|
|
|
// Smith's geometry function
|
|
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 ggx1 = GeometrySchlickGGX(NdotV, roughness);
|
|
float ggx2 = GeometrySchlickGGX(NdotL, roughness);
|
|
return ggx1 * ggx2;
|
|
}
|
|
|
|
// Fresnel term (Schlick's approximation)
|
|
vec3 FresnelSchlick(float cosTheta, vec3 F0)
|
|
{
|
|
return F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
|
|
}
|
|
|
|
// ----------------------------------------------------------------------------
|
|
void main()
|
|
{
|
|
vec3 N = normalize(vertexNormal);
|
|
vec3 V = normalize(viewPos - vertexPos);
|
|
vec3 L = normalize(lightPos - vertexPos);
|
|
vec3 H = normalize(V + L);
|
|
|
|
// Texture or uniform color
|
|
vec3 albedo = (useTexture)
|
|
? texture(diffuseTex, TexCoords).rgb
|
|
: diffuseColor;
|
|
|
|
// Map shininess to roughness (inverse relationship)
|
|
float roughness = clamp(1.0 - (shininess / 256.0), 0.05, 1.0);
|
|
|
|
// Base reflectivity (F0)
|
|
vec3 F0 = mix(vec3(0.04), specularColor, specularStrength);
|
|
|
|
// Cook-Torrance BRDF
|
|
float NDF = DistributionGGX(N, H, roughness);
|
|
float G = GeometrySmith(N, V, L, roughness);
|
|
vec3 F = FresnelSchlick(max(dot(H, V), 0.0), F0);
|
|
|
|
vec3 numerator = NDF * G * F;
|
|
float denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0) + 0.001;
|
|
vec3 specular = numerator / denominator;
|
|
|
|
// Energy conservation
|
|
vec3 kS = F;
|
|
vec3 kD = vec3(1.0) - kS;
|
|
kD *= (useSpecular ? 1.0 : 1.0); // keep diffuse always unless specular is off
|
|
|
|
float NdotL = max(dot(N, L), 0.0);
|
|
|
|
vec3 diffuse = kD * albedo / 3.14159265;
|
|
vec3 radiance = LIGHT_COLOR;
|
|
|
|
vec3 Lo = (diffuse + specular) * radiance * NdotL;
|
|
|
|
// Ambient (simple, not IBL)
|
|
vec3 ambient = ambientStrength * ambientColor * albedo;
|
|
|
|
vec3 result = ambient + Lo;
|
|
|
|
// Gamma correction
|
|
result = pow(result, vec3(1.0/2.2));
|
|
|
|
FragColor = vec4(result, opacity);
|
|
}
|