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blitting in 2D efficiency

Started by unreason Nov 3, 2004 at 5:52 AM 0 replies 600+ views

Original Post

Nov 3, 2004 at 5:52 AM

I'm writing some directX8 code to draw 2D sprites to the screen. Basically, I've got a vertex buffer with a quad in it, and by using translation, I draw it in various places, with different textures. Because it's the same quad, I can keep the vertex buffer locked, and gain some efficiency. I have a problem, though, when it comes to the texture. Obviously, the texture uv coordinates need to change so that I can draw different sprites. However, as far as I can tell, the only way I can change the uv coordinates is to lock, change, and unlock the buffer, which means a performance hit. Is there any better way of quickly changing the uv parameters used to draw the quad?

doublepoison

Nov 3, 2004 at 6:05 AM

Quote:
Original post by unreason
I'm writing some directX8 code to draw 2D sprites to the screen. Basically, I've got a vertex buffer with a quad in it, and by using translation, I draw it in various places, with different textures. Because it's the same quad, I can keep the vertex buffer locked, and gain some efficiency. I have a problem, though, when it comes to the texture. Obviously, the texture uv coordinates need to change so that I can draw different sprites. However, as far as I can tell, the only way I can change the uv coordinates is to lock, change, and unlock the buffer, which means a performance hit. Is there any better way of quickly changing the uv parameters used to draw the quad?

Just use separte quads, you won't see a great performance loss as its only two verts per quad, and it'll be faster than having a dynamic vert buffer for a single quad (the only alternative).

Also an indexed vert buffer would be faster.

double.

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