public static Matrix4 ComposeInverse( Vector3 translation, Vector3 scale, Quaternion orientation )
{
// Invert the parameters
Vector3 invTranslate = -translation;
Vector3 invScale = new Vector3( 1f / scale.x, 1f / scale.y, 1f / scale.z );
Quaternion invRot = orientation.Inverse();
// Because we're inverting, order is translation, rotation, scale
// So make translation relative to scale & rotation
invTranslate *= invScale; // scale
invTranslate = invRot * invTranslate; // rotate
// Next, make a 3x3 rotation matrix and apply inverse scale
Matrix3 rot3x3, scale3x3;
rot3x3 = invRot.ToRotationMatrix();
scale3x3 = Matrix3.Zero;
scale3x3.m00 = invScale.x;
scale3x3.m11 = invScale.y;
scale3x3.m22 = invScale.z;
// Set up final matrix with scale, rotation and translation
Matrix4 result = scale3x3 * rot3x3;
result.Translation = invTranslate;
return result;
}
