From 9ed493d19b7c7234be712336ebd2c2a5784747c0 Mon Sep 17 00:00:00 2001
From: Theis Pieter Hollebeek <tphollebeek@gmail.com>
Date: Thu, 26 Mar 2026 17:13:24 +0100
Subject: [PATCH] backface culling attempt

---
 game/src/engine/math.rs | 5 +++++
 game/src/engine/r3d.rs  | 8 +++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/game/src/engine/math.rs b/game/src/engine/math.rs
index d667d72..d598ada 100644
--- a/game/src/engine/math.rs
+++ b/game/src/engine/math.rs
@@ -20,6 +20,11 @@ impl V3 {
         let V3(bx, by, bz) = rhs;
         Self(ay * bz - az * by, az * bx - ax * bz, ax * by - ay * bx)
     }
+    pub fn dot(&self, rhs: Self) -> f64 {
+        let V3(ax, ay, az) = self;
+        let V3(bx, by, bz) = rhs;
+        ax * bx + ay * by + az * bz
+    }
 }
 
 impl Add for V3 {
diff --git a/game/src/engine/r3d.rs b/game/src/engine/r3d.rs
index da34530..5c8cda5 100644
--- a/game/src/engine/r3d.rs
+++ b/game/src/engine/r3d.rs
@@ -36,8 +36,7 @@ impl<'r, R: Renderer> R3d<'r, R> {
     }
 
     pub fn draw_line(&mut self, from: V3, to: V3, color: Color) {
-        self.r
-            .draw_line((from).project_2d(), (to).project_2d(), color);
+        self.r.draw_line(from.project_2d(), to.project_2d(), color);
     }
 
     pub fn draw_triangle(&mut self, triangle: Triangle3, color: Color) {
@@ -55,7 +54,10 @@ impl<'r, R: Renderer> R3d<'r, R> {
             let normal_vector = face.normal_vector();
             let pxyz = face.0 + normal_vector;
             self.draw_line(face.0 + pos, pxyz + pos, Color::WED);
-            if normal_vector.2 < 0.0 {
+
+            let bingbongvector = face.0 - CAMERA_POS + pos;
+            self.draw_line(face.0 + pos, V3(0.0, 0.0, -0.99), Color::WED);
+            if normal_vector.dot(bingbongvector) < 0.0 {
                 self.draw_triangle(face.translate(pos - CAMERA_POS), outline_color);
             }
         }