cocos2d for iPhone

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

1. 

   lmauri
   Member

   I want to draw a brush starting when I touch the screen and ending when I lift.

   The brush that I want to draw could be a specific texture image.

   How could I do ? I'm just watching to use RenderTexture class but I'm not sure...

   Posted 2 years ago #
2. 

   slipster216
   Moderator

   Yep, render texture is the right way to go. I have a pretty comprehensive paint program working using rendertexture as the back end. One day I'll finish it and release it..

   Posted 2 years ago #
3. 

   Codemattic
   Moderator

   Splat... was practically a painting app... with shooting!

   Posted 2 years ago #
4. 

   lmauri
   Member

   Could you please post sample code to use RenderTexture to simulate painting brush ? need help...

   Posted 2 years ago #
5. 

   xStoryTeller
   Member

   *Bump* I would be intrested in this code aswell

   Posted 2 years ago #
6. 

   slipster216
   Moderator

   You already have it; check the examples..

   Posted 2 years ago #
7. 

   xStoryTeller
   Member

   Oh sorry ! I didn't check the newest examples so I didn't see the new example. I have a question though, currently I'm using chipmunk segment shapes too draw, from the segment shapes I can get the begin and end points to draw the render texture part I think, I'm just wondering how erasing would work ? I would want the texture2d part to go away when I remove the segment shape, is this possible ? Thanks in advance,

   xStoryTeller

   Posted 2 years ago #
8. 

   slipster216
   Moderator

   Yeah, just render into the alpha channel instead of the color channels..

   Posted 2 years ago #
9. 

   xStoryTeller
   Member

   Yeah, just render into the alpha channel instead of the color channels..

   It seems like I'm annoying you somewhat, sorry ! Its my first time working with OpenGL, and Objective C aswell, I'm just trying to learn all I can. I'll try to figure out what you mean with render into the alpha channel and how to apply it, thanks a lot.

   Posted 2 years ago #
10. 

    slipster216
    Moderator

    glColorMask(FALSE, FALSE, FALSE, TRUE); // only draw into the alpha channel

    // draw some stuff

    glColorMask(TRUE, TRUE, TRUE, FALSE); // back to normal

    Posted 2 years ago #
11. 

    Steve Oldmeadow
    Administrator

    @xStoryTeller - we don't expect you to know OpenGL, we do expect you to search before you post. If it was me, I would have searched for RenderTexture and read EVERY post before I asked a question. If you had of done that you would have discovered slipster216 had added a demo to the code repository. You would have also discovered this thread where I posted code to do what you are trying to do now (i.e. erase based on alpha).

    http://www.cocos2d-iphone.org/forum/topic/2473#post-15464

    Posted 2 years ago #

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