diff --git a/KeepersCompound.Lightmapper/MathUtils.cs b/KeepersCompound.Lightmapper/MathUtils.cs
index 769fc72..64dbb85 100644
--- a/KeepersCompound.Lightmapper/MathUtils.cs
+++ b/KeepersCompound.Lightmapper/MathUtils.cs
@@ -51,4 +51,65 @@ public static class MathUtils
     {
         return Math.Abs(Vector3.Dot(plane.Normal, point) + plane.D) / plane.Normal.Length();
     }
+
+    /// <summary>
+    /// Expects poly to be convex. Given a point
+    /// </summary>
+    public static Vector3 ClipPointToPoly3d(Vector3 point, Vector3[] vertices, Plane projectionPlane)
+    {
+        // Shouldn't need to pass 3d. We can just pass the luxel coord, and then we only need the 
+
+        var (p2d, v2ds) = LocalPlaneCoords(point, vertices, projectionPlane);
+
+        // !HACK: Replace this shit
+        var origin = vertices[0];
+        var locX = vertices[1] - origin;
+        var locY = Vector3.Cross(projectionPlane.Normal, locX);
+        locX = Vector3.Normalize(locX);
+        locY = Vector3.Normalize(locY);
+
+        var inside = true;
+        for (var i = 0; i < v2ds.Length; i++)
+        {
+            var a = v2ds[i];
+            var b = v2ds[(i + 1) % v2ds.Length];
+            var segment = b - a;
+            var offset = p2d - a;
+            var norm = Vector2.Normalize(new Vector2(-segment.Y, segment.X));
+            var side = Vector2.Dot(norm, offset);
+            if (side >= -0.001)
+            {
+                p2d -= norm * (side + 0.0015f);
+                inside = false;
+            }
+        }
+
+        // return p2d;
+
+        return origin + p2d.X * locX + p2d.Y * locY;
+
+        // return Vector3.One;
+    }
+
+    // TODO: Only do this once per poly
+    public static (Vector2, Vector2[]) LocalPlaneCoords(Vector3 point, Vector3[] ps, Plane plane)
+    {
+        var origin = ps[0];
+        var locX = ps[1] - origin;
+        var locY = Vector3.Cross(plane.Normal, locX);
+
+        locX = Vector3.Normalize(locX);
+        locY = Vector3.Normalize(locY);
+
+        var offset = point - origin;
+        var p2d = new Vector2(Vector3.Dot(offset, locX), Vector3.Dot(offset, locY));
+        var p2ds = new Vector2[ps.Length];
+        for (var i = 0; i < ps.Length; i++)
+        {
+            var p = ps[i] - origin;
+            p2ds[i] = new Vector2(Vector3.Dot(p, locX), Vector3.Dot(p, locY));
+        }
+
+        return (p2d, p2ds);
+    }
 }
\ No newline at end of file
diff --git a/KeepersCompound.Lightmapper/Program.cs b/KeepersCompound.Lightmapper/Program.cs
index 4e81016..02090e8 100644
--- a/KeepersCompound.Lightmapper/Program.cs
+++ b/KeepersCompound.Lightmapper/Program.cs
@@ -259,6 +259,13 @@ class Program
                     topLeft + xDir + yDir,
                 ]);
 
+                // Used for clipping points to poly
+                var vs = new Vector3[poly.VertexCount];
+                for (var i = 0; i < poly.VertexCount; i++)
+                {
+                    vs[i] = cell.Vertices[cell.Indices[cellIdxOffset + i]];
+                }
+
                 foreach (var light in lights)
                 {
                     // Check if plane normal is facing towards the light
@@ -294,6 +301,8 @@ class Program
                             pos += x * 0.25f * renderPoly.TextureVectors.Item1;
                             pos += y * 0.25f * renderPoly.TextureVectors.Item2;
 
+                            pos = MathUtils.ClipPointToPoly3d(pos, vs, plane);
+
                             // If we're out of range there's no point casting a ray
                             // There's probably a better way to discard the entire lightmap
                             // if we're massively out of range