Sprite rotation on touch point.

venkcauk

I am trying to rotate a sprite to the point on screen where user is touching. Sprite position is at center of the screen.

I have tried with some sample code from online by calculating distance and finding rotation angle(AS3 Code). Here rotation speed is very high and Im missing some unit system that to be used in iOS.

I like to know about unit system which is followed in iOS if any. Also please share me if there is any code sample for rotating a Sprite at user touch point.

Thanks

Regards,
Venkatesh S

Daniel

I'm not sure what exactly you want to do; you want to move an object to the touch point? Or rotate it while the user is dragging it around?

If it's dragging, look at the "TouchSheet" class that comes with the demo. You can use both fingers to rotate the object.

If I misunderstood you, please try to explain it again, and I'll see what I can do!

venkcauk

Hi Daniel, Thanks for the reply.

Actually Im trying to create a navigational controller for my game object boat(top view). Here boat has to move and face towards the user touchPoint. Boat movement towards touchPoint is done. And rotation has some problem in uint conversion. Below is the code which I written for boat rotation.

float radian;
SPPoint* difference = [[SPPoint alloc] init];
difference.x = _touchPoint.x - _currentPoint.x;
difference.y = _touchPoint.y - _currentPoint.y;

radian = atan2f(difference.y, difference.x);
_paperBoat.rotation = SP_R2D(radian);

Result: Boat is rotating at its center point continuously and also moving towards touchPoint.

I have done this same logic for many times in Flash AS3 but here some thing Im missing.

Hope you understand now.

Any and all ideas and suggestions are welcome.

Thanks & Regards,
Venkatesh S

Daniel

I think the solution is rather simple: Sparrow uses "radian" for all angles, including the "rotation" property of display objects! So if you change that last line to the following:

_paperBoat.rotation = radian;

That should be it!

venkcauk

Bingo!!! Thank you very much Daniel. It working now.

-Thanks

Daniel

You're welcome! That is easy to overlook. 😉

[I was always annoyed that Flash uses sometimes degrees (display objects), sometimes radians (Point, Matrix), so I took the freedom of unifying this in Sparrow.]

venkcauk

This framework is very easy to understand. I have to write more code in sparrow framework to know about things like this 😛 Great work by sparrow team 🙂

Daniel

Thanks, venkcauk! 🙂