Transforms

Understand what a transform is

Understand how to combine transforms

转移子物体到父物体的空间中

Convert between transforms and matrices

Understand how to apply transforms to points and vectors

获得一个点在一个transform空间的位置。
http://gabormakesgames.com/transforms.html

Transform combine(const Transform& a, const Transform& b) {
	Transform out;

	out.scale = a.scale * b.scale;
	out.rotation = b.rotation * a.rotation;

	out.position = a.rotation * (a.scale * b.position);
	out.position = a.position + out.position;

	return out;
}

Matrix combine(Transform transform) {
    Matrix localMatrix = ToMatrix(transform);
    Matrix parentMatrix  = ToMatrix(transform.parent);
    return localMatrix * parentMatrix;

Matrix GetInParentMatrix(Transform transform) {
    Matrix localMatrix = ToMatrix(transform);
    Matrix localParentMatrix = ToMatrix(transform.parent);
 
    return localParentMatrix * localMatrix;
}