To the point: I have spaceship sprite (which moves and when not moving usies Sine Beh) which has couple of moving sub-sprites (panels, turrets, launchers etc) at i want them to "stick" to the image points of their destiny and mostly it works. But this is my problem - i want the sub-sprite to "float" with the parent sprite but also move having in mind the sine changing position. think about a hatch doors on side of spaceship that opens by sliding in a direction(being behind the ships) and i dont know how to set it. i want the "hatch" doors to slowly open and close when i order so but with sine beh in mind.
Ofcourse i can do the same by adding frames to the spirte but this seems more VRAM eating and less elegant (and mostly - needless)
That would be the x of your door sprite, with a leeway of 5 pixels either way. You may need to adjust to how ever wide you want it to move. Then just set its y to ship.imagepointy("point"). I'm not too sure how well that will work with sine, so you may need to make a switch using pv's.