1 files changed, 105 insertions, 0 deletions
diff --git a/advanced_lighting/4.normal_mapping/shaders/shadow.fs b/advanced_lighting/4.normal_mapping/shaders/shadow.fs
new file mode 100644
index 0000000..6a3a8b0
--- /dev/null
+++ b/advanced_lighting/4.normal_mapping/shaders/shadow.fs
@@ -0,0 +1,105 @@
+#version 330 core
+
+in VS_OUT {
+    vec3 frag_pos;
+    vec3 normal;
+    vec2 tex_coords;
+} fs_in;
+
+out vec4 frag_color;
+
+uniform vec3 light_pos;
+uniform vec3 view_pos;
+uniform float far;
+
+uniform sampler2D diffuse_texture;
+uniform samplerCube depth_cubemap;
+
+vec3 grid_sampling_disk[20] = vec3[]
+(
+   vec3(1, 1,  1), vec3( 1, -1,  1), vec3(-1, -1,  1), vec3(-1, 1,  1), 
+   vec3(1, 1, -1), vec3( 1, -1, -1), vec3(-1, -1, -1), vec3(-1, 1, -1),
+   vec3(1, 1,  0), vec3( 1, -1,  0), vec3(-1, -1,  0), vec3(-1, 1,  0),
+   vec3(1, 0,  1), vec3(-1,  0,  1), vec3( 1,  0, -1), vec3(-1, 0, -1),
+   vec3(0, 1,  1), vec3( 0, -1,  1), vec3( 0, -1, -1), vec3( 0, 1, -1)
+);
+
+float
+calculate_shadow(vec3 frag_pos)
+{
+    vec3 frag_to_light = frag_pos-light_pos;
+    /* float closest_depth = texture(depth_cubemap, frag_to_light).r; */
+    /* closest_depth *= far; */
+    float current_depth = length(frag_to_light);
+    /* float bias = 0.05; */
+    /* float shadow = current_depth-bias > closest_depth ? 1.0 : 0.0; */
+    /* NOTE(pryazha): Display depth value for debugging */
+    /* frag_color = vec4(vec3(closest_depth/far), 1.0); */
+    /*
+    float shadow = 0.0;
+    float offset = 0.1;
+    float samples = 4.0;
+    for (float x = -offset;
+         x < offset;
+         x += offset/(samples*0.5))
+    {
+        for (float y = -offset;
+             y < offset;
+             y += offset/(samples*0.5))
+        {
+            for (float z = -offset;
+                 z < offset;
+                 z += offset/(samples*0.5))
+            {
+                float closest_depth = texture(depth_cubemap, frag_to_light+vec3(x, y, z)).r;
+                closest_depth *= far;
+                if (current_depth-bias > closest_depth)
+                    shadow += 1.0;
+            }
+        }
+    }
+    shadow /= (samples*samples*samples);
+    */
+
+    float shadow = 0.0;
+    float bias = 0.15;
+    int samples = 20;
+    float view_distance = length(view_pos-frag_pos);
+    float disk_radius = (1.0+(view_distance/far))/25.0;
+    for (int sample = 0;
+         sample < samples;
+         ++sample)
+    {
+        float closest_depth = texture(depth_cubemap, frag_to_light+
+                                      grid_sampling_disk[sample]*disk_radius).r;
+        closest_depth *= far;
+        if (current_depth-bias > closest_depth)
+            shadow += 1.0;
+    }
+    shadow /= float(samples);
+    return(shadow);
+}
+
+void
+main(void)
+{
+    vec3 color = texture(diffuse_texture, fs_in.tex_coords).rgb;
+    vec3 normal = normalize(fs_in.normal);
+    vec3 light_color = vec3(0.5);
+
+    vec3 ambient = 0.5*light_color;
+    
+    vec3 light_dir = normalize(light_pos-fs_in.frag_pos);
+    float diff = max(dot(light_dir, normal), 0.0);
+    vec3 diffuse = diff*light_color;
+
+    vec3 view_dir = normalize(view_pos-fs_in.frag_pos);
+    vec3 halfway_dir = normalize(light_dir+view_dir); 
+    float spec = pow(max(dot(halfway_dir, normal), 0.0), 64.0);
+    vec3 specular = spec*light_color;
+
+    float shadow = calculate_shadow(fs_in.frag_pos);
+    vec3 lighting = (ambient+(1.0-shadow)*(diffuse+specular))*color;
+
+    frag_color = vec4(lighting, 1.0);
+}