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Texture/UV Transforms

Started by matthughson Oct 15, 2005 at 4:20 PM 1 reply 750+ views

Original Post

Oct 15, 2005 at 4:20 PM

Hey Guys, I'm working on a tile engine in Managed DX and C#. I would like to use a sprite sheet for the tile map, but I would also like to avoid locking and unlock the vertex buffer every time I switch UVs (in order to access a different tile image). I came across something called texture transforms, and it seems to be what I need; a transformation applied to the UVs in the fixed pipeline. I can't seem to get it to work though, or find much documentation on the topic. Here is what I am doing:


ManD3D.m_device.Transform.Texture0 = Matrix.Translation(new Vector3(UOffSet, VOffSet, 0.0f));

// ...render mesh

This call doesn't seem to be affecting the texture coordinates at all. Am I on the right track, or completely off here? Is there a renderstate or something I need to set? Any example code would be fantastic! Thanks! Matt Hughson [Edited by - matthughson on October 15, 2005 4:47:27 PM]

Namethatnobodyelsetook

118

Namethatnobodyelsetook

Oct 15, 2005 at 6:52 PM

Matrices for 2D vectors are slightly different. See here where I describe how to make it work.

Having said that, draw calls have a huge overhead, so setting a texture transform and world transform for each tile is going to be slow. For things like tile engines and particle systems you're better off making a dynamic vertex buffer, which is optimized for sending new vertices to the card without stalling. I briefly describe how to use a dynamic VB here. Using this technique and sprite sheets is the optimal way to do a tile engine. Mix in alphatesting to get shaped sprites with accurate Z buffering, and you're all set.

MasterWorks

Oct 16, 2005 at 1:46 AM

Dynamic VBs are definitely the way to go, as Namethatnobodyelsetook said. I don't think the texture transform matrices are going to help you here. With a dynamic VB, you'll be recreating all the vertices for all the sprites every frame so you can use whatever TU/TVs you would like. This makes animation with a sprite sheet very easy also.

Eventually you could use a dynamic index buffer in combination so that you can render 2 triangles with 4 vertices instead of 6.

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