Cleanup in VSM code

Shader/bump.fs

@@ -53,7 +53,7 @@ vec2 get_parallax_offset_uv(vec2 uv, vec3 view_direction) {
         current_layer_depth += refinement_layer_depth;  
     }
 
-    // Referse the UV operation again and return the result
+    // Reverse the UV operation again and return the result
     current_uv += uv_refine_shift_per_layer;
 
     return current_uv;
@@ -78,17 +78,19 @@ float get_shadow(vec4 fragPosLightSpace, vec3 normal) {
 
     // get closest depth value from light's perspective (using [0,1] range fragPosLight as coords)
     mediump float closestDepth = moments.r; 
+    mediump float depth_squared = moments.g;
     // get depth of current fragment from light's perspective
     mediump float currentDepth = projCoords.z;
     // check whether current frag pos is in shadow
-    float p = step(projCoords.z, moments.x);
+    float p = step(currentDepth, closestDepth);
 
     // We divide by this later, so make sure it's not exactly 0
     // It seems like it should always be 0.0, but due to interpolation it's not -- it increases with the deviation!
     // A larger second parameter to max() means more blur (but also more light bleeding)
-    float variance = max(moments.y - moments.x * moments.x, (-0.01 + (currentDepth - closestDepth) * 0.7) * 0.1);
+    float variance = max(depth_squared - closestDepth * closestDepth, (-0.01 + (currentDepth - closestDepth) * 0.7) * 0.1);
+
+    float d = currentDepth - closestDepth;
     
-    float d = projCoords.z - moments.x * 1.0;
     // Use linear_step to prevent light bleeding
     float p_max = linear_step(0.2, 1.0, variance / (variance + d * d));