138 lines
4.0 KiB
GLSL
138 lines
4.0 KiB
GLSL
#ifndef LIGHTING_COMMON_GLSL
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#define LIGHTING_COMMON_GLSL
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const float PI = 3.14159265359;
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float pow5(float x)
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{
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float x2 = x * x;
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return x2 * x2 * x;
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}
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vec3 fresnelSchlick(float cosTheta, vec3 F0)
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{
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float m = clamp(1.0 - cosTheta, 0.0, 1.0);
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return F0 + (1.0 - F0) * pow5(m);
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}
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float DistributionGGX(vec3 N, vec3 H, float roughness)
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{
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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 / max(denom, 0.001);
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}
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float GeometrySchlickGGX(float NdotV, float roughness)
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{
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float r = (roughness + 1.0);
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float k = (r * r) / 8.0;
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float denom = NdotV * (1.0 - k) + k;
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return NdotV / max(denom, 0.001);
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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 ggx2 = GeometrySchlickGGX(max(dot(N, V), 0.0), roughness);
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float ggx1 = GeometrySchlickGGX(max(dot(N, L), 0.0), roughness);
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return ggx1 * ggx2;
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}
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vec3 evaluate_brdf(vec3 N, vec3 V, vec3 L, vec3 albedo, float roughness, float metallic)
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{
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vec3 H = normalize(V + L);
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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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vec3 F0 = mix(vec3(0.04), albedo, metallic);
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vec3 F = fresnelSchlick(max(dot(H, V), 0.0), F0);
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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 numerator = NDF * G * F;
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float denom = 4.0 * NdotV * NdotL;
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vec3 specular = numerator / max(denom, 0.001);
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vec3 kS = F;
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vec3 kD = (1.0 - kS) * (1.0 - metallic);
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return (kD * albedo / PI + specular) * NdotL;
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}
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vec3 eval_point_light(GPUPunctualLight light, vec3 pos, vec3 N, vec3 V, vec3 albedo, float roughness, float metallic)
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{
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vec3 lightPos = light.position_radius.xyz;
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float radius = max(light.position_radius.w, 0.0001);
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vec3 toLight = lightPos - pos;
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float dist2 = dot(toLight, toLight);
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if (dist2 <= 1.0e-8)
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{
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return vec3(0.0);
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}
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float invDist = inversesqrt(dist2);
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float dist = dist2 * invDist;
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vec3 L = toLight * invDist;
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// Smooth falloff: inverse-square with soft clamp at radius
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float att = 1.0 / max(dist2, 1.0e-8);
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float x = clamp(dist / radius, 0.0, 1.0);
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float smth = (1.0 - x * x);
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smth *= smth;
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float falloff = att * smth;
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vec3 brdf = evaluate_brdf(N, V, L, albedo, roughness, metallic);
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vec3 lightColor = light.color_intensity.rgb * light.color_intensity.a;
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return brdf * lightColor * falloff;
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}
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vec3 eval_spot_light(GPUSpotLight light, vec3 pos, vec3 N, vec3 V, vec3 albedo, float roughness, float metallic)
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{
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vec3 lightPos = light.position_radius.xyz;
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float radius = max(light.position_radius.w, 0.0001);
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vec3 toLight = lightPos - pos;
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float dist2 = dot(toLight, toLight);
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if (dist2 <= 1.0e-8)
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{
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return vec3(0.0);
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}
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float invDist = inversesqrt(dist2);
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float dist = dist2 * invDist;
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vec3 L = toLight * invDist; // surface -> light
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// direction_cos_outer.xyz is expected to be unit length (normalized on the CPU).
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vec3 dir = light.direction_cos_outer.xyz; // light -> forward
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float cosOuter = light.direction_cos_outer.w;
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float cosInner = light.cone.x;
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float cosTheta = dot(-L, dir); // light -> surface vs light forward
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if (cosTheta <= cosOuter)
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{
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return vec3(0.0);
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}
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float denom = max(cosInner - cosOuter, 0.0001);
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float spot = clamp((cosTheta - cosOuter) / denom, 0.0, 1.0);
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spot *= spot;
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// Smooth falloff: inverse-square with soft clamp at radius
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float att = 1.0 / max(dist2, 1.0e-8);
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float x = clamp(dist / radius, 0.0, 1.0);
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float smth = (1.0 - x * x);
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smth *= smth;
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float falloff = att * smth;
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vec3 brdf = evaluate_brdf(N, V, L, albedo, roughness, metallic);
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vec3 lightColor = light.color_intensity.rgb * light.color_intensity.a;
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return brdf * lightColor * falloff * spot;
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}
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#endif // LIGHTING_COMMON_GLSL
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