feature: add eulerFromMat4, eulerFromQuaternion

src/math/euler/eulerFromMat4.ts

@@ -0,0 +1,16 @@
+import { eulerFromMat3 } from './eulerFromMat3';
+import { mat3FromMat4 } from '../mat3/mat3FromMat4';
+import type { EulerOrder } from './EulerOrder';
+import type { RawMatrix4 } from '../mat4/RawMatrix4';
+import type { RawVector3 } from '../vec3/RawVector3';
+
+/**
+ * Return a euler angles out of a matrix4.
+ * Make sure the input matrix is normalized.
+ *
+ * @param m An input rotation matrix
+ * @param order An order of output euler angles. Assume as `XYZ` if not specified
+ */
+export function eulerFromMat4( m: RawMatrix4, order?: EulerOrder ): RawVector3 {
+  return eulerFromMat3( mat3FromMat4( m ), order );
+}

src/math/euler/eulerFromQuaternion.ts

@@ -0,0 +1,15 @@
+import { eulerFromMat3 } from './eulerFromMat3';
+import { mat3FromQuaternion } from '../mat3/mat3FromQuaternion';
+import type { EulerOrder } from './EulerOrder';
+import type { RawQuaternion } from '../quat/RawQuaternion';
+import type { RawVector3 } from '../vec3/RawVector3';
+
+/**
+ * Return a euler angles out of a quaternion.
+ *
+ * @param m An input quaternion
+ * @param order An order of output euler angles. Assume as `XYZ` if not specified
+ */
+export function eulerFromQuaternion( m: RawQuaternion, order?: EulerOrder ): RawVector3 {
+  return eulerFromMat3( mat3FromQuaternion( m ), order );
+}

src/math/euler/index.ts

@@ -1,2 +1,4 @@
 export * from './eulerFromMat3';
+export * from './eulerFromMat4';
+export * from './eulerFromQuaternion';
 export * from './EulerOrder';

src/math/euler/tests/eulerFromMat4.test.ts

@@ -0,0 +1,19 @@
+import '../../../tests/matchers/toBeCloseToArray';
+import { eulerFromMat4 } from '../eulerFromMat4';
+import type { RawMatrix4 } from '../../mat4/RawMatrix4';
+
+const mat4X45Y45Z45: RawMatrix4 = [
+  0.500,  0.500, -0.707, 0.0,
+  -0.146,  0.854,  0.500, 0.0,
+  0.854, -0.146,  0.500, 0.0,
+  0.0, 0.0, 0.0, 1.0,
+];
+
+describe( 'eulerFromMat4', () => {
+  it( 'returns an euler angles out of a matrix4', () => {
+    const subject = eulerFromMat4( mat4X45Y45Z45, 'XYZ' );
+    expect( subject ).toBeCloseToArray( [ 0.785, 0.785, 0.785 ] );
+  } );
+
+  // See eulerFromMat3.test.ts for more in-depth test cases
+} );

src/math/euler/tests/eulerFromQuaternion.test.ts

@@ -0,0 +1,14 @@
+import '../../../tests/matchers/toBeCloseToArray';
+import { eulerFromQuaternion } from '../eulerFromQuaternion';
+import type { RawQuaternion } from '../../quat/RawQuaternion';
+
+const quatX45Y45Z45: RawQuaternion = [ 0.191, 0.461, 0.191, 0.844 ];
+
+describe( 'eulerFromQuaternion', () => {
+  it( 'returns an euler angles out of a quaternion', () => {
+    const subject = eulerFromQuaternion( quatX45Y45Z45, 'XYZ' );
+    expect( subject ).toBeCloseToArray( [ 0.785, 0.785, 0.785 ] );
+  } );
+
+  // See eulerFromMat3.test.ts for more in-depth test cases
+} );