OpenGL Texture Loading & Sprites

Posts: 2
Joined: 2007.12
Post: #1
I've been trying to get started with OpenGL programming for a while now. I've been using it in Xcode with Cocoa. I can setup the view, create and move colored boxes and do collision detection. The one thing that repeatedly stumps me, though is textures. What I would like to eventually be able to do is to create a 2D side-scrolling game and use OpenGL to draw my sprites and etc. I have a hard time with loading textures, and I don't know how to approach sprites with OpenGL, though. If someone has an example that would show how to load textures (containing alpha channels that should be applied) and use them as sprites that would be very helpful.

I'd appreciate any help and direction.

- Corporate Newt
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⌘-R in Chief
Posts: 1,277
Joined: 2002.05
Post: #2
See this thread, particularly OneSadCookie's post:

For sprites, all you have to do is simply stick a texture on a simple quad. Bam.

Is there a more specific question you had?
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Posts: 16
Joined: 2008.01
Post: #3
Well its more than just slapping a texture onto a Quad...

Sprites are usually animated so you will need several frames of animation. This is easy to achieve - you just load the texture with all the frames, bind it to the Quad, then change the texture coordinates at a particular time period (about every tenth of a second - it will vary depending on the effect you want to achieve).

Then there is the dreaded alpha bending to allow the alpha channel to actually work - this should be covered in tutorials - so that the sprite is not just displayed as a quad.

If you are working in 3D in any way (even for 2D games) you may want to sort your sprites for depth so that the sprites overlap properly, the so-called painter's algorithm, which just means drawing the furthest items first!

And then finally, sprites generally do different things: go left, go right, fire, blow up etc - so the list of textures for any particular character needs to be tied together by some loose data structure such as an array.

Incidently, I use FutureBASIC (which I find a lot easier to use than C ).
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