some prb examples

1 files changed, 105 insertions, 0 deletions

diff --git a/pbr/2.1.1.ibl_irradiance_conversion/pbr.frag b/pbr/2.1.1.ibl_irradiance_conversion/pbr.frag
new file mode 100644
index 0000000..db9edea
--- /dev/null
+++ b/pbr/2.1.1.ibl_irradiance_conversion/pbr.frag
@@ -0,0 +1,105 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+	vec3 normal;
+} vert;
+
+out vec4 frag_color;
+
+uniform vec3 camera;
+
+uniform vec3 color;
+uniform float metallic;
+uniform float roughness;
+uniform float ao;
+
+struct light_t {
+	vec3 position;
+	vec3 color;
+};
+
+const int light_count = 4;
+uniform light_t lights[light_count];
+
+const float PI = 3.14159265358; 
+
+vec3 fresnel_shlick(float costheta, vec3 f0)
+{
+	return f0 + (1.0 - f0) * pow(1.0 - costheta, 5.0);
+}
+
+float distribution_ggx(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 geometry_shlick_ggx(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 geometry_smith(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 = geometry_shlick_ggx(ndotv, roughness);
+	float ggx1 = geometry_shlick_ggx(ndotl, roughness);
+
+	return ggx1 * ggx2;
+}
+
+void main(void)
+{
+	vec3 n = vert.normal;
+	vec3 v = normalize(camera - vert.position);
+
+	vec3 lo = vec3(0.0);
+	for (int i = 0; i < light_count; i++) {
+		vec3 l = normalize(lights[i].position - vert.position);
+		vec3 h = normalize(v + l);
+		float ndotv = max(dot(n, v), 0.0);
+		float ndotl = max(dot(n, l), 0.0);
+
+		float distance = length(lights[i].position - vert.position);
+		float attenuation = 1.0 / (distance * distance);
+
+		vec3 radiance = lights[i].color * attenuation;
+
+		vec3 f0 = vec3(0.04);
+		f0 = mix(f0, color, metallic);
+		vec3 f = fresnel_shlick(max(dot(h, v), 0.0), f0);
+
+		float ndf = distribution_ggx(n, h, roughness);
+		float g = geometry_smith(n, v, l, roughness);
+
+		vec3 numerator = ndf * g * f;
+		float denominator = 4.0 * ndotv * ndotl;
+		vec3 specular = numerator / max(denominator, 0.001);
+
+		vec3 ks = f;
+		vec3 kd = vec3(1.0) - ks;
+
+		kd *= 1.0 - metallic;
+
+		lo += (kd * color / PI + specular) * radiance * ndotl;
+	}
+	
+	vec3 ambient = vec3(0.03) * color * ao;
+	frag_color = vec4(ambient + lo, 1.0);
+}