Adds Triangle3d primitive to dim3.rs

crates/bevy_math/src/primitives/dim3.rs

@@ -629,6 +629,57 @@ impl Torus {
  }
 }
 
+/// A 3D triangle primitive.
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+pub struct Triangle3d {
+ /// The vertices of the triangle
+ pub vertices: [Vec3; 3],
+}
+
+impl Primitive3d for Triangle3d {}
+
+impl Default for Triangle3d {
+ /// Returns the default [`Triangle3d`] with vertices at the `[-0.5, 0.0, 0.0]`, `[0.5, 0.0, 0.0]`, and `[0.0, 0.5, 0.0]`
+ fn default() -> Self {
+ Self {
+ vertices: [Vec3::ZERO, Vec3::X, Vec3::Y],
+ }
+ }
+}
+
+impl Triangle3d {
+ /// Create a new [`Triangle3d`] from points `a`, `b`, and `c`
+ #[inline(always)]
+ pub fn new(a: Vec3, b: Vec3, c: Vec3) -> Self {
+ Self {
+ vertices: [a, b, c],
+ }
+ }
+
+ /// Get the area of the triangle
+ #[inline(always)]
+ pub fn area(&self) -> f32 {
+ let [a, b, c] = self.vertices;
+ let ab = a.distance(b);
+ let bc = b.distance(c);
+ let ca = c.distance(a);
+
+ let s = (ab + bc + ca) / 2.0;
+ (s * (s - ab) * (s - bc) * (s - ca)).sqrt()
+ }
+
+ /// Get the perimeter of the triangle
+ #[inline(always)]
+ pub fn perimeter(&self) -> f32 {
+ let [a, b, c] = self.vertices;
+ let ab = a.distance(b);
+ let bc = b.distance(c);
+ let ca = c.distance(a);
+ ab + bc + ca
+ }
+}
+
 #[cfg(test)]
 mod tests {
  // Reference values were computed by hand and/or with external tools