cocos2d for iPhone

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

1. 

   Decept
   Member

   It's my first time using PVRTC textures and I can't get my sprite to show anything. I have converted a 32bit 512x512 PNG file with the exact parameters as others have used on this forum. I load the texture and create a sprite like this:

   sprite = [Sprite spriteWithTexture:[[TextureMgr sharedTextureMgr] addPVRTCImage:@"test.pvr"]];

   and I position and add it to the layer. But I only get a black screen. If I instead load the original file "test.png" everything is fine.

   I've been at it for some time now and searched the forum again and again, but I still can't get it to work.

   Posted 2 years ago #
2. 

   abitofcode
   Moderator

   I'm using cocos2D v0.8 and the following works for me (see Texture2dText.m);
   

   Sprite *sausage = [Sprite spriteWithFile:@"sausage.pvr"];
   sausage.position = ccp(150,150);
   [self addChild:sausage z:500];

   I use the following to compress the sausage;
   

   texturetool -e PVRTC --channel-weighting-linear --bits-per-pixel-4 -f PVR -o sausage.pvr -p sausage256.tif sausage256.png

   If you find you have lots of blurry artifacts around the edge of your texture have a look at the following article over at veiled studios, particularly affects line art.

   http://www.veiledgames.com/blog/?p=355

   Posted 2 years ago #
3. 

   Steve Oldmeadow
   Administrator

   Imagination Technologies (makers of the GPU) have recently released versions of their OpenGL ES SDKs for Mac OS. The SDK includes GUI tools for working with PVRTC files. You just need to sign up to their developer program.

   http://www.imgtec.com/powervr/insider/powervr-sdk.asp

   Posted 2 years ago #
4. 

   Decept
   Member

   Thanks you!

   I thought I've tested all possible combinations of loading a pvrtc file, but I managed to miss the one you used, which of course worked. I tried to following lines in combination with different texturetool parameters and source image files.

   // These do NOT work
   sprite = [Sprite spriteWithTexture:[[TextureMgr sharedTextureMgr] addPVRTCImage:@"test.pvr"]];
   sprite = [Sprite spriteWithTexture:[[TextureMgr sharedTextureMgr] addPVRTCImage:@"test.pvrtc"]];
   sprite = [Sprite spriteWithFile:@"test.pvrtc"];

   // This one does work
   sprite = [Sprite spriteWithFile:@"test.pvr"];

   I think it's strange that the addPVRTCImage do not work, why is that?

   Also a follow-up question, how big will a pvr texture be in memory? As I understand it, it doesn't get decoded to a 32bit texture.

   Posted 2 years ago #
5. 

   abitofcode
   Moderator

   Searched for addPVRTCImage in the cocos2d demos (Shift+Command+F), the fourth result is;

   AccelViewportTest.m which contains the following example;
   

   Texture2D *tex = [[TextureMgr sharedTextureMgr] addPVRTCImage:@"clouds.pvrtc" bpp:4 hasAlpha:NO width:1024];
   clouds = [Sprite spriteWithTexture:tex];

   Pvr textures use linear compression so you can predict how much memory they will consume (not something i've had to worry about so far), Png's can very quickly fill up he available memory when uncompressed if not careful, don't confuse the files footprint size with its uncompressed size in memory.

   Remember to stick to within powers of 2, as I understand it an image 129 x 129 will result in the texture memory having to expand to the next power of 2 to accommodate it i.e 256 x 256.

   I've been having 'fun' recently with limiting the artifacts on the line art for a game I'm writing, I found the suggestion from veiled studios about increasing the size of the image used for the pvr and then using a scaled down version in the game seems to work.

   Posted 2 years ago #

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