From 9e9254b04c5149efb21d43d58ffc71c5dd96b1bf Mon Sep 17 00:00:00 2001
From: hodasemi <michaelh.95@t-online.de>
Date: Mon, 15 May 2023 09:04:57 +0200
Subject: [PATCH] Fix points ordering

---
 src/global_state.rs |  2 +-
 src/polygon.rs      | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/global_state.rs b/src/global_state.rs
index f504f3c..c385c09 100644
--- a/src/global_state.rs
+++ b/src/global_state.rs
@@ -29,7 +29,7 @@ impl GlobalState {
             window_extent: Vec2::default(),
             polygon_started: false,
             view_2d: true,
-            extrusion_height: 20.0,
+            extrusion_height: 50.0,
 
             offscreen_image,
             offscreen_image_size,
diff --git a/src/polygon.rs b/src/polygon.rs
index 74b6900..3edde6a 100644
--- a/src/polygon.rs
+++ b/src/polygon.rs
@@ -145,6 +145,8 @@ impl Polygon {
                 }
             }
 
+            self.order_points();
+
             // create triangle mesh
             let triangle_mesh = self.create_triangulated_mesh();
 
@@ -272,6 +274,23 @@ impl Polygon {
         }
     }
 
+    fn order_points(&mut self) {
+        let n = Vec3::Z;
+
+        let v1 = (self.points[0] - self.points[1]).normalize().extend(0.0);
+        let v2 = (self.points[1] - self.points[2]).normalize().extend(0.0);
+
+        let c1 = v1.cross(n);
+
+        let d = c1.dot(v2);
+
+        // dot product is bigger than 0 if normal and connection line are facing in the same direction
+        // reverse the order of points, thus the face of the 3d object is directed to the outside
+        if d >= 0.0 {
+            self.points = self.points.iter().cloned().rev().collect();
+        }
+    }
+
     fn check_all_for_proximity(&self, point: Vec2) -> bool {
         self.points
             .iter()