cocos2d for iPhone

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

1. 

   generalrelativity
   Member

   I'm trying to render a large number of separated pixels like the screen on a GameBoy. I'm new to OpenGL and so I'd like to get some advice on what sorts of ways I can approach this problem.

   I'm currently rendering like so:
   

   glColorPointer( 4, GL_FLOAT, 0, &colors );
   glVertexPointer( 2, GL_FLOAT, 0, &triangles );	
   
   glDrawArrays( GL_TRIANGLES, 0, sizeof( triangles ) / sizeof( CGPoint ) );

   so i build an array of 6 (vertices per pixel) * numPixels. Is this an appropriate approach? I have no idea if this will scale up etc--any thoughts/advice is appreciated.

   Thanks!

   Posted 1 year ago #
2. 

   araker
   Moderator

   How many pixels do you want to create this way ? The pixels don't overlap, so you won't be fillrate limited. The most likely bottleneck you'll first encounter is being vertex limited, the vertex information has to be copied to the gl memory every frame, which of course takes more time if you have a lot of them.

   Some general optimizations,

   Use glDrawElements, it uses a index array so you can reuse vertices. There are numerous tutorials online which draw a cube with glDrawElements. That will get you started.

   To reduce the number of vertices you could use GL_TRIANGLE_STRIP with degenerate triangles, although I wouldn't try this until your implementation is working. Too much early optimization is often a waste of time.

   EDIT read the OpenGL ES programming guide, it has best practices in it (link). How to structure and align your data will also be very useful for you.

   Posted 1 year ago #
3. 

   vanillasky65
   Member

   Would it be easier to create an image that looks like a pixel and render it on a Sprite Sheet?

   Posted 1 year ago #
4. 

   JKyy
   Member

   Why don't you draw your picture normally, maybe with little upscaling with no-antialiasing and overlay a grid over that? You could use OpenGL primitives or have a texture as your grid. I am not sure, but I would guess that still is more efficient way to do it.

   Posted 1 year ago #
5. 

   generalrelativity
   Member

   Thanks for the suggestions. Seems to be rendering fine how I posted originally, and I do strongly agree with not worrying about optimization too much so I think I'll stick with that and revisit and try some of araker's suggestions.

   @vanillasky65: i want to be able to set any color, ideally, so i think that's not the best approach for me

   @JKyy: i don't have faith that that will look perfect. my engine turns the whole of my game scene into a vector of colors, so being able to apply this directly to opengl seems attractive.

   Thanks again!

   Posted 1 year ago #

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