Exported phong into its own file

src/illumination/shading.h

@@ -0,0 +1,20 @@
+#ifndef SHADING_H
+#define SHADING_H
+
+#include "linalg/linalg.h"
+#include "consts.h"
+
+// TODO: Consider wrapping this in a class (?)
+__device__ Vec3 phongShading(const Vec3& normal, const Vec3& lightDir, const Vec3& viewDir, const Vec3& baseColor) {
+    Vec3 ambient = baseColor * ambientStrength;
+    double diff = fmax(normal.dot(lightDir), 0.0);
+    Vec3 diffuse = baseColor * (diffuseStrength * diff);
+
+    Vec3 reflectDir = (normal * (2.0 * normal.dot(lightDir)) - lightDir).normalize();
+    double spec = pow(fmax(viewDir.dot(reflectDir), 0.0), shininess);
+    Vec3 specular = Vec3(1.0, 1.0, 1.0) * (specularStrength * spec);
+
+    return ambient + diffuse + specular;
+}
+
+#endif // SHADING_H