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assets/shaders/fragment_temp.glsl

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+#version 330 core
+
+struct Light {
+    vec3 direction;
+    vec3 ambient;
+    vec3 diffuse;
+    vec3 specular;
+};
+
+out vec4 FragColor;
+
+in vec3 frag_normal;
+in vec3 fragPos;
+in vec4 frag_pos_light_space;
+
+uniform sampler2D shadow_map;
+uniform vec3 viewPos;
+
+uniform float perceptualRoughness; //  [0, 1]
+uniform float metallic; // [0, 1]
+uniform float reflectance; // [0, 1]
+uniform vec3  baseColor;
+
+uniform Light light;
+
+float shadow_factor(vec4 frag_pos_light_space)
+{
+    vec3 proj_coords = frag_pos_light_space.xyz / frag_pos_light_space.w;
+    proj_coords = proj_coords * 0.5 + 0.5;
+
+    float closest_depth = texture(shadow_map, proj_coords.xy).r;
+    float current_depth = proj_coords.z;
+
+    float bias = 0.005;
+    float shadow = 0;
+    vec2 delta = 1.0 / textureSize(shadow_map, 0);
+    for (int i = -1; i < 2; i++)
+        for (int j = -1; j < 2; j++) {
+            float closest_depth = texture(shadow_map, proj_coords.xy + vec2(i, j) * delta).r;
+            shadow += (current_depth - bias > closest_depth) ? 1.0 : 0.0;
+        }
+    shadow /= 9;
+    return shadow;
+}
+
+float D_GGX(float NoH, float a) {
+    float a2 = a * a;
+    float f = (NoH * a2 - NoH) * NoH + 1.0;
+    return a2 / (PI * f * f);
+}
+
+vec3 F_Schlick(float u, vec3 f0) {
+    return f0 + (vec3(1.0) - f0) * pow(1.0 - u, 5.0);
+}
+
+float V_SmithGGXCorrelated(float NoV, float NoL, float a) {
+    float a2 = a * a;
+    float GGXL = NoV * sqrt((-NoL * a2 + NoL) * NoL + a2);
+    float GGXV = NoL * sqrt((-NoV * a2 + NoV) * NoV + a2);
+    return 0.5 / (GGXV + GGXL);
+}
+
+float Fd_Lambert() {
+    return 1.0 / PI;
+}
+
+void main()
+{
+    // NOTE: frag_normal is normalized by the vertex shader
+/*
+    vec3 l = normalize(light.direction);
+    vec3 v = viewDir;
+    vec3 n = frag_normal;
+    vec3 h = normalize(v + l);
+    vec3 diffuseColor = (1.0 - metallic) * baseColor.rgb;
+    vec3 f0 = 0.16 * reflectance * reflectance * (1.0 - metallic) + baseColor * metallic;
+
+    float NoV = abs(dot(n, v)) + 1e-5;
+    float NoL = clamp(dot(n, l), 0.0, 1.0);
+    float NoH = clamp(dot(n, h), 0.0, 1.0);
+    float LoH = clamp(dot(l, h), 0.0, 1.0);
+
+    float roughness = perceptualRoughness * perceptualRoughness;
+
+    float D = D_GGX(NoH, roughness);
+    vec3  F = F_Schlick(LoH, f0);
+    float V = V_SmithGGXCorrelated(NoV, NoL, roughness);
+
+    // specular BRDF
+    vec3 Fr = (D * V) * F;
+
+    //vec3 energyCompensation = 1.0 + f0 * (1.0 / dfg.y - 1.0);
+    //// Scale the specular lobe to account for multiscattering
+    //Fr *= pixel.energyCompensation;
+
+    // diffuse BRDF
+    vec3 Fd = diffuseColor * Fd_Lambert();
+
+    // apply lighting...
+
+    float shadow = shadow_factor(frag_pos_light_space);
+*/
+    vec3 result = vec3(1, 0, 0); // Fd + Fr * (1 - shadow);
+    FragColor = vec4(result, 1.0);
+}