X-Git-Url: http://git.lukelau.me/?p=opengl.git;a=blobdiff_plain;f=pbrfrag.glsl;fp=pbrfrag.glsl;h=4421b99b6021a9e6a7da4953122bebf30bbf2499;hp=0000000000000000000000000000000000000000;hb=a03f2bc751bbd7f91cbc2f52d2f0f6e753d6f776;hpb=210d1b08cec40845d849e89baea8a9cc96917f60

diff --git a/pbrfrag.glsl b/pbrfrag.glsl
new file mode 100644
index 0000000..4421b99
--- /dev/null
+++ b/pbrfrag.glsl
@@ -0,0 +1,107 @@
+#version 330
+
+#define mdot(x, y) (max(dot(x, y), 0.f))
+
+in vec3 worldPos, normal;
+in vec2 texCoords;
+
+uniform vec3 camPos;
+
+uniform sampler2D albedoMap;
+uniform sampler2D normalMap;
+uniform sampler2D metallicMap;
+uniform sampler2D roughnessMap;
+uniform sampler2D aoMap;
+
+out vec4 fragColor;
+
+uniform vec3 lightPositions[4];
+uniform vec3 lightColors[4];
+
+const float PI = 3.14159265359;
+
+vec3 fresnelSchlick(float cosTheta, vec3 F0) {
+	return F0 + (1.f - F0) * pow(1.f - cosTheta, 5.f);
+}
+
+float distributionGGX(vec3 N, vec3 H, float roughness) {
+	float a = roughness * roughness;
+	float NdotH = mdot(N, H);
+	float denom = (NdotH * NdotH) * ((a * a) - 1.f) + 1.f;
+	denom = PI * denom * denom;
+	return (a * a) / denom;
+}
+
+float geometrySchlickGGX(float NdotV, float roughness) {
+	float r = roughness + 1.f;
+	float k = (r * r) / 8.f;
+	return NdotV / (NdotV * (1.f - k) + k);
+}
+
+float geometrySmith(vec3 N, vec3 V, vec3 L, float roughness) {
+	float ggx1 = geometrySchlickGGX(mdot(N, L), roughness);
+	float ggx2 = geometrySchlickGGX(mdot(N, V), roughness);
+	return ggx1 * ggx2;
+}
+
+vec3 getNormalFromMap() {
+	vec3 tangentNormal = texture(normalMap, texCoords).xyz * 2.f - 1.f;
+	vec3 Q1 = dFdx(worldPos);
+    vec3 Q2 = dFdy(worldPos);
+    vec2 st1 = dFdx(texCoords);
+    vec2 st2 = dFdy(texCoords);
+
+    vec3 N = normalize(normal);
+    vec3 T = normalize(Q1 * st2.t - Q2 * st1.t);
+    vec3 B = -normalize(cross(N, T));
+    mat3 TBN = mat3(T, B, N);
+
+    return normalize(TBN * tangentNormal);
+}
+
+void main() {
+	vec3 albedo = pow(texture(albedoMap, texCoords).rgb, vec3(2.2));
+	vec3 normal = getNormalFromMap();
+	float metallic = texture(metallicMap, texCoords).r;
+	float roughness = texture(roughnessMap, texCoords).r;
+	float ao = texture(aoMap, texCoords).r;
+
+	vec3 N = normalize(normal);
+	vec3 V = normalize(camPos - worldPos);
+
+	vec3 F0 = mix(vec3(0.04), albedo, metallic);
+
+	// reflectance
+	vec3 Lo = vec3(0.f);
+	for (int i = 0; i < lightPositions.length(); i++) {
+		vec3 L = normalize(lightPositions[i] - worldPos);
+		vec3 H = normalize(V + L);
+
+		// calculate radiance
+		float dist = length(lightPositions[i] - worldPos);
+		float attenuation = 5.f / (dist * dist);
+		vec3 radiance = lightColors[i] * attenuation;
+
+		// cook-torrance brdf
+		vec3 F = fresnelSchlick(mdot(H, V), F0);
+		float NDF = distributionGGX(N, H, roughness);
+		float G = geometrySmith(N, V, L, roughness);
+
+		float denom = 4.f * mdot(N, V) * mdot(N, L);
+		vec3 specular = (NDF * G * F) / max(denom, 0.0000001);
+
+		vec3 kS = F; // fresnel = reflection ratio
+		vec3 kD = vec3(1.f) - kS;
+		kD *= 1.f - metallic;
+
+		Lo += (kD * albedo / PI + specular) * radiance * mdot(N, L);
+	}
+
+	vec3 ambient = vec3(0.03) * albedo * ao;
+	vec3 color = ambient + Lo;
+
+	color = color / (color + vec3(1.f)); // map to HDR
+	color = pow(color, vec3(1.f / 2.2)); // gamma correction
+
+	fragColor = vec4(color, 1.f);
+}