update method
Implementation
@override
void update(int dirt) {
ActorShape shape = parent as ActorShape;
Mat2D world = shape.worldTransform;
if (shape.transformAffectsStroke) {
Vec2D.copy(_renderStart, _start);
Vec2D.copy(_renderEnd, _end);
} else {
Vec2D.transformMat2D(_renderStart, _start, world);
Vec2D.transformMat2D(_renderEnd, _end, world);
}
}