Fix axis layout and implement click raytracing

src/tests/mod.rs

@@ -0,0 +1,39 @@
+#[cfg(test)]
+mod tests {
+    use cgmath::{vec3};
+
+    use crate::game::player::{intersect_triangle};
+
+    fn epsilon_eq(f1: f32, f2: f32) {
+        assert!(f32::abs(f1 - f2) < f32::EPSILON, "{} == {}", f1, f2);
+    }
+
+    fn epsilon_eq_option(o1: Option<f32>, o2: Option<f32>) {
+        if let Some(f1) = o1 {
+            if let Some(f2) = o2 {
+                epsilon_eq(f1, f2);
+            } else {
+                panic!("Some({}) == None", f1);
+            }
+        } else if let Some(f2) = o2 {
+            panic!("None == Some({})", f2);
+        }
+    }
+
+    #[test]
+    fn triangle_intersection() {
+        let zero = vec3(0.0, 0.0, 0.0);
+        let a = [2.0, 0.5, 0.5];
+        let b = [2.0, -0.5, 0.5];
+        let c = [2.0, 0.0, -0.5];
+
+        let dist1 = intersect_triangle(zero, vec3(1.0, 0.0, 0.0), a, b, c);
+        epsilon_eq_option(dist1, Some(2.0));
+
+        let dist2 = intersect_triangle(zero, vec3(0.0, 0.0, 1.0), a, b, c);
+        epsilon_eq_option(dist2, None);
+
+        let dist3 = intersect_triangle(zero, vec3(0.9950371902, 0.09950371902, 0.0), a, b, c);
+        epsilon_eq_option(dist3, Some(2.0099751242));
+    }
+}