diff --git a/engine/art/shaderlib/shadowmap.glsl b/engine/art/shaderlib/shadowmap.glsl
index 5d53f74..bf536b4 100644
--- a/engine/art/shaderlib/shadowmap.glsl
+++ b/engine/art/shaderlib/shadowmap.glsl
@@ -23,7 +23,6 @@ vec2 shadow_vsm_variance(vec3 dir, int light_index, float distance, float min_va
     return vec2(linstep(variance_transition, 1.0, variance / (variance + d * d)), moments.x);
 }
 
-//// From http://fabiensanglard.net/shadowmappingVSM/index.php
 float shadow_vsm(float distance, vec3 dir, int light_index, float min_variance, float variance_transition, float shadow_softness_raw) {
     distance = distance / 200;
     float shadow_softness = shadow_softness_raw * 10.0;
@@ -37,16 +36,23 @@ float shadow_vsm(float distance, vec3 dir, int light_index, float min_variance,
     vec4 sc = vec4(dir, 1.0);
     sc.z = dir.z;
 
-    vec2 texelSize = 1.0 / textureSize(shadowMap[light_index], 0);
+    vec2 tex_size = textureSize(shadowMap[light_index], 0);
+    vec3 texelSize = 1.0 / vec3(tex_size.xyy);
+    vec3 light_plane_normal = normalize(dir);
+    vec3 tangent = normalize(cross(light_plane_normal, vec3(0.0, 1.0, 0.0)));
+    vec3 bitangent = cross(light_plane_normal, tangent);
 
     for (int i = 0; i < 4; i++) {
         ofs_coord.x = i;
         vec4 offsets = texelFetch(shadow_offsets, ofs_coord, 0) * shadow_softness;
-        sc.xy = dir.xy + offsets.rg * texelSize;
+
+        vec3 offset_dir = tangent * offsets.r + bitangent * offsets.g;
+        sc.xyz = dir.xyz + offset_dir * texelSize;
         vec2 variance = shadow_vsm_variance(sc.xyz, light_index, distance, min_variance, variance_transition);
         ofs_sum += min(max(step(distance, variance.y), variance.x), 1.0);
 
-        sc.xy = dir.xy + offsets.ba * texelSize;
+        offset_dir = tangent * offsets.b + bitangent * offsets.a;
+        sc.xyz = dir.xyz + offset_dir * texelSize;
         variance = shadow_vsm_variance(sc.xyz, light_index, distance, min_variance, variance_transition);
         ofs_sum += min(max(step(distance, variance.y), variance.x), 1.0);
     }
@@ -57,11 +63,14 @@ float shadow_vsm(float distance, vec3 dir, int light_index, float min_variance,
         for (int i = 4; i < samples_div2; i++) {
             ofs_coord.x = i;
             vec4 offsets = texelFetch(shadow_offsets, ofs_coord, 0) * shadow_softness;
-            sc.xy = dir.xy + offsets.rg * texelSize;
+
+            vec3 offset_dir = tangent * offsets.r + bitangent * offsets.g;
+            sc.xyz = dir.xyz + offset_dir * texelSize;
             vec2 variance = shadow_vsm_variance(sc.xyz, light_index, distance, min_variance, variance_transition);
             ofs_sum += min(max(step(distance, variance.y), variance.x), 1.0);
 
-            sc.xy = dir.xy + offsets.ba * texelSize;
+            offset_dir = tangent * offsets.b + bitangent * offsets.a;
+            sc.xyz = dir.xyz + offset_dir * texelSize;
             variance = shadow_vsm_variance(sc.xyz, light_index, distance, min_variance, variance_transition);
             ofs_sum += min(max(step(distance, variance.y), variance.x), 1.0);
         }