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VertexBuffer with multiple textures

Started by ProgrammerDX Sep 21, 2010 at 5:47 AM 2 replies 1.9k views

Original Post

Sep 21, 2010 at 5:47 AM

Hey

When you have a vertex buffer you use DrawPrimitive. And if you have a texture you use SetTexture first.

But if you have a vertex buffer that uses alot of textures, what to do?

Evil Steve

Sep 21, 2010 at 5:50 AM

Assuming you mean you want the textures displayed seperately and not combined in some way, you make multiple calls to SetTexture and DrawPrimitive to draw only the primitives textured with one particular material.

For instance, if you have a cube, where each face has a different texture applied, you'd make 8 calls to SetTexture and 8 calls to DrawPrimitive, one for each face.

ProgrammerDX

Sep 21, 2010 at 5:56 AM

Thanks for your answer.

But the Vertex Buffer defines the whole Cube object? Wouldnt DirectX (underlying Graphic Card) try to draw the full cube every call to DrawPrimitive, which would create more load?

Evil Steve

Sep 21, 2010 at 6:18 AM

Quote:
Original post by ProgrammerDX
Thanks for your answer.

But the Vertex Buffer defines the whole Cube object? Wouldnt DirectX (underlying Graphic Card) try to draw the full cube every call to DrawPrimitive, which would create more load?

The vertex buffer contains vertices, not objects. You define the object based on the parameters you pass to DrawPrimitive().

So, your loop would be something like:

for(int i=0; i<8; ++i){   pDevice->SetTexture(0, textures);   pDevice->DrawPrimitive(D3DPT_TRIANGLESTRIP, i*4, 2);}

I.e. draw two triangles, starting from vertex 0, 4, 8, 12, 16, 20, 24, or 28.

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