Wednesday, July 17, 2013

CocosBuilder and CGPaths for non-rect Tap Detection

This is just a short post to frame a video how-to on detecting taps for selection on touchscreen devices, using CGPaths - and how to create those CGPaths using CocosBuilder.

What this essentially does is makes CocosBuilder into a tool that you can use to create non-rectangular bounding paths for tap detection.  As a bonus, I show how you can use the CGPath information to create a blue selection sprite image to signify the active selection in the UI.

I reference Bob Ueland's excellent CGPath tutorial, and that does include some code that you can use for the actual hit test.

For the extraction of the CGPath data from the CocosBuilder file I am not posting my code for cutting-and-pasting but if you've followed my earlier tutorials and are building your own game in Cocos2D you should have enough knowledge to follow what I have done.  It is just simply a case of traversing the nodes and using the standard method to build up a path from the CGPoint information stored in the CCNodes.

My technique for creating a selection sprite from the CGPath data is also not tricky - just check the documentation.  Give it a try and if you get really stuck feel free to ask a question here or on G+.

Hope it helps, and enjoy selecting stuff!