From d2c4c385df2594a5d4369f2af2f6a7b5d66bdd8c Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Sun, 5 Jan 2025 17:57:08 +1100
Subject: basic pbr

---
 intermediate/surface.glsl | 66 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 52 insertions(+), 14 deletions(-)

(limited to 'intermediate/surface.glsl')

diff --git a/intermediate/surface.glsl b/intermediate/surface.glsl
index 0f55016..2d5d470 100644
--- a/intermediate/surface.glsl
+++ b/intermediate/surface.glsl
@@ -27,9 +27,6 @@ type: vec2
 name: position
 type: vec4
 [interpolator]
-name: normal
-type: vec3
-[interpolator]
 name: tbn
 type: mat3
 
@@ -56,6 +53,9 @@ type: float
 [variable]
 name: ao
 type: float
+[variable]
+name: camera_pos
+type: vec3
 
 [cbuffer]
 name: c_mvp
@@ -101,7 +101,6 @@ void main() {
 	vec3 t = normalize((c_mvp.model * vec4(tangent, 0.0)).xyz);
 	vec3 n = normalize((c_mvp.model * vec4(normal, 0.0)).xyz);
 	vec3 b = cross(t, n);
-	interpolator.normal = n;
 	interpolator.tbn = mat3(t, b, n);
 	interpolator.uv = uv;
 	interpolator.position = pos;
@@ -113,23 +112,62 @@ void main() {
 
 #ifdef FRAGMENT_SHADER
 
+#define pi 3.14159265358979323846
+
+vec3 diffuse_brdf(vec2 uv) {
+	vec3 a = material.albedo * texture(albedo, uv).rgb;
+	return a / pi;
+}
+
+float specular_G1(float a, vec3 v, vec3 n) {
+	float ndv = max(dot(n, v), 0.0);
+	float a1 = a + 1.0;
+	float k = (a1 * a1) / 8.0;
+	return ndv / (ndv * (1.0 - k) + k);
+}
+
+float specular_brdf(vec2 uv, vec3 l, vec3 v, vec3 n) {
+	float ndl = max(dot(n, l), 0.0);
+	float ndv = max(dot(n, v), 0.0);
+	vec3 ref = reflect(-l, n);  
+	float a = texture(rough, uv).r * material.roughness;
+	float a2 = a * a;
+	float ndr = max(dot(n, ref), 0.0);
+	float b = ((ndr * ndr) * (a2 - 1) + 1);
+	float D =
+		a2 / (pi * b * b);
+	float G = specular_G1(a, l, n) * specular_G1(a, v, n);
+	float F0 = G;
+	float F = F0 + (1.0 - F0) *
+		pow(2, ((-5.55473 * ndr - 6.98316), ndr));
+	return (D * F * G) / (4.0 * ndl * ndv);
+}
+
 void main() {
 	vec2 uv = interpolator.uv;
+	vec3 p = interpolator.position.xyz;
 
 	vec3 nrmsample = texture(normal, uv).rgb;
-
 	vec2 nrmxy = nrmsample.xy * 2.0 - 1.0;
 	vec3 nrm = normalize(vec3(nrmxy, 1.0));
 	if (nrmsample.b == 1.0) /* default texture */
-		nrm = vec3(0, 0, 1);
-	nrm = normalize(interpolator.tbn * nrm);
-
-	float light = max(dot(nrm, vec3(0, 0, 1)), 0.0);
-
-	vec3 ambient = 0.05.xxx * texture(ao, uv).r;
-	vec3 col = ambient + light * material.albedo;
-	col *= texture(albedo, uv).rgb;
-	colour = vec4(col, 1.0);
+		nrm = normalize(interpolator.tbn[2]);
+	else
+		nrm = normalize(interpolator.tbn * nrm);
+
+	vec3 light_dir = vec3(0, 0, 1);
+	vec3 col = texture(albedo, uv).rgb * material.albedo;
+	float cos_theta_i = max(dot(nrm, light_dir), 0.0);
+	vec3 view_dir = normalize(material.camera_pos - p);
+
+	vec3 diffuse =
+		diffuse_brdf(uv) *
+		cos_theta_i;
+	float spec =
+		specular_brdf(uv, light_dir, view_dir, nrm) *
+		cos_theta_i;
+
+	colour = vec4(diffuse + vec3(spec), 1.0);
 }
 
 #endif
-- 
cgit v1.2.3-54-g00ecf