feat: Quaternion#fromEulerXYZ

src/quaternion.ts

@@ -8,9 +8,9 @@ export class Quaternion {
     public y: number,
     public z: number,
     public w: number,
-  ) { }
+  ) {}
 
-  static fromXYZ({
+  public static fromXYZ({
     x,
     y,
     z,
@@ -24,6 +24,27 @@ export class Quaternion {
     return new Quaternion(x, y, z, w);
   }
 
+  public static fromEulerXYZ(
+    roll: number,
+    pitch: number,
+    yaw: number,
+  ): Quaternion {
+    const cx = math.cos(roll * 0.5);
+    const sx = math.sin(roll * 0.5);
+    const cy = math.cos(pitch * 0.5);
+    const sy = math.sin(pitch * 0.5);
+    const cz = math.cos(yaw * 0.5);
+    const sz = math.sin(yaw * 0.5);
+
+    // Quaternion multiplication order: q = qx * qy * qz (X → Y → Z)
+    const w = cx * cy * cz + sx * sy * sz;
+    const x = sx * cy * cz - cx * sy * sz;
+    const y = cx * sy * cz + sx * cy * sz;
+    const z = cx * cy * sz - sx * sy * cz;
+
+    return new Quaternion(x, y, z, w);
+  }
+
   public toEuler(): Vec3 {
     const { x, y, z, w } = this;