CODEWITHSUNDEEP
opengltile
Semicolon
Semicolon

Reputation: 163

Techniques for drawing tiles with OpenGL

I've been using XNA for essentialy all of my programming so far and would like to move on to OpenGL (along with SFML for IO, creating the window etc.) with C++ . For starters I'd like to create a tile-based game and I've mostly looked at LazyFoo's tutorials.

I just have a two questions:

How should I draw the tiles? Should I use immediate drawing, arrays, VBOs or what? VBOs feel like overkill for this but I'm not sure. It's very tempting to use immediate drawing but apparently it's deprecated. Maybe it's fine for this purpose since it's 2D and only for a bunch of quads.

I'd like a lot of different tiles and thus all of my tiles will not fit into a single texture without making it massive. I've read that using bindTexture isn't very cheap and thus I should avoid as many calls as I can. I thought that maybe I can create a manager for my textures and stitch them all together into one big texture and bind that but then the dimensions of that is an issue.

Upvotes: 2

Views: 1258

Answers (2)

datenwolf
datenwolf

Reputation: 162164

Don't use immediate mode! It's cumbersome to work with and has been removed from recent OpenGL versions. Use Vertex Arrays, ideally through VBOs. In the end they're much easier to use, believe me.

Regarding that switching of textures. We're talking about optimizing the texture switch patterns in very complex scenes. In your case it will hardly matter at all.

Update

Right now you worry abount things without having even used them. That's worse than premature optimization. I suggest you first get a good grip on OpenGL, then start worrying about state switch management.

Upvotes: 2

Ron Warholic
Ron Warholic

Reputation: 10074

With regards to the texture atlas; this is usually done by stitching textures into groups of power-of-two sized textures. For example in a tile-based game you might have a particular tile set (say, tiles for an ice world) grouped together on 2 or 3 textures. When you want to render them you would determine what tiles are visible, then you bind each texture once and render the tiles from that texture for any tiles that are visible on screen.

This requires quite a lot of set-up time to get right; you need keep information on each sub-texture of the atlas so you can find the right texture and render the appropriate region of that texture whenever a tile is referenced. You also need a good way of grouping rendering operations so that they occur when the appropriate texture is bound.

Like datenwolf said, I wouldn't focus too much on complicated texture systems early on; eager binding of textures will be plenty fast enough until you get further down the road.

Upvotes: 0

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