cocos2d for iPhone

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

1. 

   daniel.mfreitas
   Member

   Hello guys. I'm implementing a path algorithm like the one used in Flight Control. So far the end result looks very good (visually speaking). The problem is that I am using CCSprite to draw the actual lines instead of applying a texture to a polygon (as advised in several places around the net).

   I just wanted something quick so I could see the results on screen and using Sprites allowed me to avoid the OpenGL intricacies.

   But I have this feeling that using Sprites for that is not the right approach. It feels like overkill. But in case I don't have the time to learn OpenGL and decide to stick with Sprites is there anything I should be aware of? There could be a lot of sprites at one point on screen, depending how complex is the path the user has traced.

   On the same note, isn't CCTexture2D supposed to work "out of the box"? The documentation for the drawRect method says "draws a texture inside a rect". I tried the following code and it gave me a BAD_ACCESS.

   CCTexture2D *texture = [[CCTextureCache sharedTextureCache] addImage: @"path_texture.png"];
   [texture drawInRect:CGRectMake(100, 100, 50, 50)];

   I got the same error while trying to use OpenGL directly, following some tutorials over the net.

   Any help appreciated.

   Posted 1 year ago #
2. 

   Steve Oldmeadow
   Administrator

   If you draw your sprites using a CCSpriteSheet so that the drawing is batched then you will get good performance. You can look at the performance reports in the Wiki to see what sort of performance you will get for a given number of sprites.

   I'm not sure why you are trying to use CCTexture2D - there would be no performance benefit. However, if you get a bad access error then type "bt" in the debugger console and post the back trace so we can determine where the problem occurred.

   Posted 1 year ago #
3. 

   daniel.mfreitas
   Member

   Thank you very much for the info. I will look into the CCSpriteSheet and the performance charts. The texture for the line is a small 8x16 png image that gets repeated on the sprite to give the path a "dotty" aspect so memory would not be an issue i think (as the same image is used for all sprites).

   I asked about CCTexture2D just because initially I wanted to do the rendering of the polygons myself. First because that's all that I needed (not rotation, no animation and no effects - that's why I though sprites could be overkill). Secondly, I like to know what's going on behind the scenes :P.

   But now that I'm thinking about it, the path coordinates are relative to the game's world and not to the screen. The position on the screen would change as the world moves around. In that case, if the sprites already have this logic built in, they will save a lot of time as I won't have to write the logic to do the conversion myself.

   Posted 1 year ago #
4. 

   daniel.mfreitas
   Member

   Here's the trace. The texture allocation and drawing was done in the draw method directly.

   #0  0x072b2693 in gleRunVertexSubmitImmediate ()
   #1  0x072b177c in gleLLVMArrayFunc ()
   #2  0x072b1734 in gleSetVertexArrayFunc ()
   #3  0x072a0d7c in gleDrawArraysOrElements_ExecCore ()
   #4  0x072a12ef in gleDrawArraysOrElements_IMM_Exec ()
   #5  0x005fb0a0 in glDrawArrays ()
   #6  0x00061a29 in -[CCTexture2D(Drawing) drawInRect:] (self=0x3a0de60, _cmd=0x90e41070, rect={origin = {x = 100, y = 100}, size = {width = 8, height = 16}}) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/libs/cocos2d/CCTexture2D.m:461
   #7  0x000039e2 in -[HelloWorld draw] (self=0x3a0c860, _cmd=0x90e4266c) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/Classes/HelloWorldScene.m:157
   #8  0x0003e839 in -[CCNode visit] (self=0x3a0c860, _cmd=0x8bcf6) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/libs/cocos2d/CCNode.m:476
   #9  0x0003e921 in -[CCNode visit] (self=0x3a0c790, _cmd=0x8bcf6) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/libs/cocos2d/CCNode.m:480
   #10 0x00023a75 in -[CCDirector mainLoop] (self=0x3e07950, _cmd=0x83906) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/libs/cocos2d/CCDirector.m:251
   #11 0x0002539a in -[CCDirector runWithScene:] (self=0x3e07950, _cmd=0x837ce, scene=0x3a0c790) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/libs/cocos2d/CCDirector.m:653
   #12 0x00003195 in -[FollowRouteDemoAppDelegate applicationDidFinishLaunching:] (self=0x3e02260, _cmd=0x98b9f622, application=0x3e00840) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/Classes/FollowRouteDemoAppDelegate.m:54
   #13 0x007075cb in -[UIApplication _performInitializationWithURL:sourceBundleID:] ()
   #14 0x007109b6 in -[UIApplication _runWithURL:sourceBundleID:] ()
   #15 0x0070db34 in -[UIApplication handleEvent:withNewEvent:] ()
   #16 0x0070967f in -[UIApplication sendEvent:] ()
   #17 0x00710061 in _UIApplicationHandleEvent ()
   #18 0x02869d59 in PurpleEventCallback ()
   #19 0x01f81b80 in CFRunLoopRunSpecific ()
   #20 0x01f80c48 in CFRunLoopRunInMode ()
   #21 0x00707e15 in -[UIApplication _run] ()
   #22 0x00710faf in UIApplicationMain ()
   #23 0x00002e64 in main (argc=1, argv=0xbfffef44) at /Users/dfreitas/dev/projects/iphone/FollowRouteDemo/main.m:13

   Posted 1 year ago #
5. 

   Steve Oldmeadow
   Administrator

   From the documentation of drawInRect
   

   These functions require GL_TEXTURE_2D and both GL_VERTEX_ARRAY and GL_TEXTURE_COORD_ARRAY client states to be enabled.

   my guess is you didn't do that?

   Anyway, there is probably no point trying to get it to work. It may seem weird using CCSpriteSheet for an 8x16 png but the main benefit of CCSpriteSheet is that you can draw all your sprites in one hit so if you had 200 sprites that is one draw call versus 200 draw calls if you use plain old sprites.

   Posted 1 year ago #

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