diff --git a/src/drawables/shapes/droplet-factory.ts b/src/drawables/shapes/droplet-factory.ts
index 76289a3..1c8c7ad 100644
--- a/src/drawables/shapes/droplet-factory.ts
+++ b/src/drawables/shapes/droplet-factory.ts
@@ -41,7 +41,7 @@ export const DropletFactory = (color: vec3 | vec4 | number): typeof DropletBase
             
             float h = clamp(
                 dot(targetFromDelta, toFromDeltas[i])
-              / dot(toFromDeltas[i], toFromDeltas[i]),
+              / max(dot(toFromDeltas[i], toFromDeltas[i]), 0.00000001),
               0.0, 1.0
             );
 
diff --git a/src/drawables/shapes/inverted-tunnel-factory.ts b/src/drawables/shapes/inverted-tunnel-factory.ts
index e219576..e0d3c4e 100644
--- a/src/drawables/shapes/inverted-tunnel-factory.ts
+++ b/src/drawables/shapes/inverted-tunnel-factory.ts
@@ -63,7 +63,7 @@ export const InvertedTunnelFactory = (
             vec2 targetFromDelta = target - froms[i];
 
             float h = dot(targetFromDelta, toFromDeltas[i])
-              / dot(toFromDeltas[i], toFromDeltas[i]);
+              / max(dot(toFromDeltas[i], toFromDeltas[i]), 0.00000001);
 
             float clampedH = clamp(h, 0.0, 1.0);
 
diff --git a/src/drawables/shapes/noisy-polygon-factory.ts b/src/drawables/shapes/noisy-polygon-factory.ts
index 3ca55fa..aba0d93 100644
--- a/src/drawables/shapes/noisy-polygon-factory.ts
+++ b/src/drawables/shapes/noisy-polygon-factory.ts
@@ -40,7 +40,8 @@ export const NoisyPolygonFactory = (
             vec2 targetFromDelta = target - from;
             vec2 toFromDelta = to - from;
             float h = clamp(
-              dot(targetFromDelta, toFromDelta) / dot(toFromDelta, toFromDelta),
+              dot(targetFromDelta, toFromDelta)
+                / max(dot(toFromDelta, toFromDelta), 0.00000001),
               0.0, 1.0
             );
 
@@ -135,9 +136,13 @@ export const NoisyPolygonFactory = (
       vec2.scale(center, center, 1 / transformedVertices.length);
 
       let length = 0;
-      for (let i = 1; i < this.vertices.length; i++) {
+      for (let i = 1; i < transformedVertices.length; i++) {
         length += vec2.distance(transformedVertices[i - 1], transformedVertices[i]);
       }
+      length += vec2.distance(
+        transformedVertices[transformedVertices.length - 1],
+        transformedVertices[0]
+      );
 
       return {
         vertices: transformedVertices,
diff --git a/src/drawables/shapes/polygon-factory.ts b/src/drawables/shapes/polygon-factory.ts
index c093ea9..04f35a1 100644
--- a/src/drawables/shapes/polygon-factory.ts
+++ b/src/drawables/shapes/polygon-factory.ts
@@ -31,7 +31,8 @@ export const PolygonFactory = (
             vec2 targetFromDelta = target - from;
             vec2 toFromDelta = to - from;
             float h = clamp(
-              dot(targetFromDelta, toFromDelta) / dot(toFromDelta, toFromDelta),
+              dot(targetFromDelta, toFromDelta)
+                / max(dot(toFromDelta, toFromDelta), 0.00000001),
               0.0, 1.0
             );
 
@@ -93,6 +94,10 @@ export const PolygonFactory = (
     constructor(vertices: Array<vec2>) {
       super(vertices);
 
+      if (vertices.length === 0) {
+        throw new Error('Polygons must have at least one vertex');
+      }
+
       if (vertices.length > vertexCount) {
         throw new Error(
           `Too many vertices, expected ${vertexCount}, got ${vertices.length}`
@@ -104,7 +109,7 @@ export const PolygonFactory = (
       const startEnd = this.vertices[0];
       let vb = startEnd;
 
-      let d = vec2.squaredDistance(target, vb);
+      let d = vec2.distance(target, vb);
       let sign = 1;
 
       for (let i = 1; i <= this.vertices.length; i++) {
@@ -141,9 +146,9 @@ export const PolygonFactory = (
     private get actualVertices(): Array<vec2> {
       return this.vertices.length < vertexCount
         ? ([
-            ...this.vertices,
-            ...new Array(vertexCount - this.vertices.length).fill(this.vertices[0]),
-          ] as Array<vec2>)
+          ...this.vertices,
+          ...new Array(vertexCount - this.vertices.length).fill(this.vertices[0]),
+        ] as Array<vec2>)
         : this.vertices;
     }
 
diff --git a/src/drawables/shapes/rotated-rectangle-factory.ts b/src/drawables/shapes/rotated-rectangle-factory.ts
index 1672669..83e0506 100644
--- a/src/drawables/shapes/rotated-rectangle-factory.ts
+++ b/src/drawables/shapes/rotated-rectangle-factory.ts
@@ -39,7 +39,7 @@ export const RotatedRectangleFactory = (
               vec2 top = rotatedRectangleTopCenters[i];
               vec2 bottom = rotatedRectangleBottomCenters[i];
               float height = length(bottom - top);
-              vec2 d = (bottom - top) / height;
+              vec2 d = height > 0.00000001 ? (bottom - top) / height : vec2(0.0, 1.0);
 
               vec2 q = (target - (top + bottom) * 0.5);
               q = mat2(d.x, -d.y, d.y, d.x) * q;