diff --git a/src/main.rs b/src/main.rs
index 492c69b..48885b5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -87,12 +87,11 @@ async fn main() {
 		);
 
 		for (w1, w2) in dd.get_walls() {
-			shadows::draw_wall(
-				w1.as_f32(),
-				w2.as_f32(),
-				mouse_position,
-				LIGHT_RADIUS,
-			);
+			let w1 = w1.as_f32();
+			let w2 = w2.as_f32();
+			if shadows::wall_needs_to_be_drawn(w1, w2, mouse_position, LIGHT_RADIUS) {
+				shadows::draw_wall(w1, w2, mouse_position, LIGHT_RADIUS);
+			}
 		}
 
 		dd.update();
diff --git a/src/shadows.rs b/src/shadows.rs
index 0ff009a..c53a98f 100644
--- a/src/shadows.rs
+++ b/src/shadows.rs
@@ -1,3 +1,4 @@
+use macroquad::prelude::Mat2;
 use macroquad::prelude::draw_triangle;
 use macroquad::prelude::DVec2;
 use macroquad::prelude::draw_mesh;
@@ -52,7 +53,22 @@ pub fn draw_wall(a: Vec2, b: Vec2, light_source: Vec2, radius: f32) {
 	draw_triangle(b_prime, a_prime, opposite_src, BLACK);
 }
 
-pub fn draw_polygon(points: &[Vec2], color: Color) {
+pub fn wall_needs_to_be_drawn(a: Vec2, b: Vec2, light_source: Vec2, radius: f32) -> bool {
+	let a = a - light_source;
+	let b = b - light_source;
+	let delta = a - b;
+	let unit = delta / delta.length();
+
+	let a_dot = unit.dot(a);
+	let b_dot = unit.dot(b);
+
+	let d = Mat2::from_cols(unit, a).determinant();
+
+	(d < radius && d > -radius) && (
+		a.length() < radius ||
+		b.length() < radius ||
+		(a_dot < 0. && b_dot > 0.) || (a_dot > 0. && b_dot <  0.)
+	)
 }
 
 /*/// Code adapted from https://github.com/not-fl3/macroquad/issues/174