cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   shadhex
   Member

   Anyone tried using the stencil buffer with cocos2d? I don't think it's part of opengl es 2.0, but it is only available on the 3gs from what I can tell. I was hoping I could detect the 3gs or greater device and make use of it in cocos2d

   The effect I'd like to do is to have 2 backgrounds, and display one of them only when a stencil is applied on the screen. The only way I can think of doing it is using a stencil buffer, texture combiner (yeurk) or shaders. Since it doesn't seem to be very straight forward to add support for ogles 2.0 in cocos2d (anyone done it yet?) I'm stuck with option a or b. Unless someone else has a better suggestion.

   Cheers!

   Posted 1 year ago #
2. 

   randomtruth
   Member

   You could add an image that has transparent and opaque pixels on top of the first image. so that the first image is only visible through the transparent pixels of the second image.

   Posted 1 year ago #
3. 

   Lam
   Member

   @shadhex
   Right now cocos2d doesn't have support for opengl es 2.0 I had to resort to running a texture combiner to do my masking.

   I'm not quite sure why you are so apprehensive about using texture combiners (yeurk?) but it wasn't too hard to implement and get working.

   But I would love to see opengles2.0 supported. There are a lot of considerations since we'd have to switch from our fixed function pipeline implementations to a vertex/fragment shader pipeline and probably the easiest way for devs to use cocos2d is to still allow support for both somehow.

   If I really wanted to have opengles2.0 support, I should really help out by adding that support into cocos2d's project. (That's the open source mentality :D )

   I heard of gles2-bc on googlecode by jsvuorin. It supports backwards compatibility with opengles 1.1 but I haven't read enough through it to understand if that would aid in implementing opengles2.0 for cocos2d.

   Anyway I'm rambling again... if you would like me to show some examples of using texture combiners (it's really simple example though ) for masking images like a stencil buffer would have done then just ask.

   Posted 1 year ago #
4. 

   shadhex
   Member

   @randomthruth I don't know where those transparent or opaque pixels should be, that's where the mask comes in handy.

   @Lam I use to love the "freedom" of texture combiner, but that's before I could use just a few simple line of shader code to do the same effect. We've all been spoiled I guess. Time to go back to the red book.

   I'm not sure how big an effort it would be to change cocos2d to opengles2.0, I don't believe it would be that great...getting it to support both would be much harder. I agree with you, right now, it would be costly for anyone to drop opengles1.1 support. IPad only application might have that luxury, but not the other idevices.

   gles2-bc looks very interesting, I'm curious how exactly it's going to work, I guess I should start with his thesis.

   Thanks for the feedback guys! Guess I'll give the combiner a shot.

   Cheers

   Posted 1 year ago #

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