PBR

konabot/plugins/marchtoy/shaders/frag.glsl

@@ -2,6 +2,7 @@
 const float EPS = 0.001;
 const int MAX_ITER = 128;
 const float INF = 1e10;
+const float PI = 3.14159;
 
 uniform vec2 u_resolution;
 out vec4 fragColor;
@@ -68,17 +69,76 @@ vec3 nrm(vec3 p) {
     ));
 }
 
+float saturate(float x) {
+    return clamp(x, 0.0, 1.0);
+}
+
+float ggx_distribution(vec3 n, vec3 h, float roughness) {
+    float alpha = roughness * roughness;
+    float alpha2 = alpha * alpha;
+    float NdotH = saturate(dot(n, h));
+    float denom = NdotH * NdotH * (alpha2 - 1.0) + 1.0;
+    return alpha2 / max(PI * denom * denom, EPS);
+}
+
+float geometry_schlick_ggx(float NdotX, float roughness) {
+    float r = roughness + 1.0;
+    float k = r * r / 8.0;
+    return NdotX / max(NdotX * (1.0 - k) + k, EPS);
+}
+
+float geometry_smith(vec3 n, vec3 v, vec3 l, float roughness) {
+    float NdotV = saturate(dot(n, v));
+    float NdotL = saturate(dot(n, l));
+    return geometry_schlick_ggx(NdotV, roughness) * geometry_schlick_ggx(NdotL, roughness);
+}
+
+vec3 fresnel_schlick(vec3 f0, float cos_theta) {
+    return f0 + (1.0 - f0) * pow(1.0 - saturate(cos_theta), 5.0);
+}
+
+vec3 tonemap_aces(vec3 c) {
+    const float a = 2.51;
+    const float b = 0.03;
+    const float c1 = 2.43;
+    const float d = 0.59;
+    const float e = 0.14;
+    return clamp((c * (a * c + b)) / (c * (c1 * c + d) + e), 0.0, 1.0);
+}
+
 vec4 materialColor(int obj_id) {
     <COLOR_BLOCK>
     return vec4(1.0);
 }
 
-vec4 color(vec3 p, int obj_id) {
-    vec3 normal = nrm(p);
-    vec3 light_dir = normalize(vec3(0.5, 0.8, -0.6));
-    float light = 0.2 + 0.8 * max(dot(normal, light_dir), 0.0);
-    vec4 base = materialColor(obj_id);
-    return vec4(base.rgb * light, base.a);
+vec4 color(vec3 p, vec3 r, int obj_id) {
+    vec3 light_col = vec3(1.0);
+    vec4 albedo = materialColor(obj_id);
+    vec3 N = nrm(p);
+    vec3 V = normalize(-r);
+    vec3 L = normalize(vec3(0.5, 0.8, -0.6));
+    vec3 H = normalize(V + L);
+    float roughness = 0.45;
+    float metallic = 0.02;
+    float NdotL = saturate(dot(N, L));
+    float NdotV = saturate(dot(N, V));
+    float D = ggx_distribution(N, H, roughness);
+    float G = geometry_smith(N, V, L, roughness);
+    vec3 F0 = mix(vec3(0.04), albedo.rgb, metallic);
+    vec3 F = fresnel_schlick(F0, dot(V, H));
+    vec3 kD = (1.0 - F) * (1.0 - metallic);
+    vec3 diffuse = kD * albedo.rgb / PI;
+    vec3 specular = D * G * F / max(4.0 * NdotL * NdotV, EPS);
+
+    float hemi = N.y * 0.5 + 0.5;
+    vec3 sky_ambient = vec3(0.60, 0.72, 0.92);
+    vec3 ground_ambient = vec3(0.18, 0.16, 0.14);
+    vec3 ambient = mix(ground_ambient, sky_ambient, hemi) * (diffuse + 0.25 * F0) * 0.35;
+
+    vec3 col = ambient + (diffuse + specular) * light_col * NdotL;
+    col = tonemap_aces(col);
+    col = pow(col, vec3(1.0 / 2.2));
+    return vec4(col, 1.0);
 }
 
 vec4 march(vec3 p, vec3 r) {
@@ -87,7 +147,7 @@ vec4 march(vec3 p, vec3 r) {
     for(int i = 0; i < MAX_ITER; ++i) {
         qry = sd(p);
         if(qry.value < EPS){
-            col = color(p, qry.obj_id);
+            col = color(p, r, qry.obj_id);
             break;
         }
         p += qry.value * r;