feat: basic shadow map + renderdoc labels

destrum/assets_src/shaders/lighting.glsl

@@ -44,7 +44,7 @@ float calculateSpotAttenuation(Light light, vec3 l)
 }
 
 vec3 calculateLight(Light light, vec3 fragPos, vec3 n, vec3 v,
-                    vec3 diffuseColor, float roughness, float metallic, vec3 f0)
+                    vec3 diffuseColor, float roughness, float metallic, vec3 f0, float occlusion)
 {
     vec3 l;
     float attenuation = 1.0;
@@ -80,7 +80,7 @@ vec3 calculateLight(Light light, vec3 fragPos, vec3 n, vec3 v,
     vec3 kd = (vec3(1.0) - F) * (1.0 - metallic);
     vec3 diffuse = kd * diffuseColor / PI;
 
-    return (diffuse + specular) * light.color * light.intensity * attenuation * NoL;
+    return (diffuse + specular) * light.color * light.intensity * attenuation * NoL * occlusion;
 }
 
 // blue -> green -> red, used to visualise how many lights a tile has