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littletray26

Locking a D3DXMesh's vertex buffer

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Hey GameDev

 

I'm trying to lock an LPD3DXMESH's vertex buffer so as I can fiddle with the vertices.

My problem is that as follows:

 

When you manually create a mesh in code, you have your own CUSTOMVERTEX kind of struct, and then when you lock the vertex buffer, you can hand it a void pointer to your CUSTOMVERTEX type. EG

	CUSTOMVERTEX* vert;
	vb->Lock(0, 0, (void**)&vert, NULL);

But when I need to lock the meshs vertex buffer, I don't have a vertex class to lock it with.

 

So my question is, how do I lock the mesh vertex buffer when I don't have a vertex struct? Is there a kind of default vertex stuct I can use?

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Hey GameDev
 
I'm trying to lock an LPD3DXMESH's vertex buffer so as I can fiddle with the vertices.
My problem is that as follows:
 
When you manually create a mesh in code, you have your own CUSTOMVERTEX kind of struct, and then when you lock the vertex buffer, you can hand it a void pointer to your CUSTOMVERTEX type. EG

	CUSTOMVERTEX* vert;
	vb->Lock(0, 0, (void**)&vert, NULL);
But when I need to lock the meshs vertex buffer, I don't have a vertex class to lock it with.
 
So my question is, how do I lock the mesh vertex buffer when I don't have a vertex struct? Is there a kind of default vertex stuct I can use?

 


The ID3DXMesh interface is derived form the ID3DXBaseMesh interface, which includes several lock functions, as described here

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You don't need a struct to lock a buffer, that's just for convenience (like you said: to manually/programmatically create a mesh).

If you're looking for such a convenience, well you probably want to provide structs for all the vertex formats you want to work with.

You can, however, retrieve enough information programmatically to work without a struct. ID3DXBaseMesh::GetDeclaration will get you the vertex declaration, D3DXGetDeclVertexSize thereof gives you the stride. Lock the buffer and offset the (BYTE!) pointer with index*stride to get to a particular vertex' start, offset again by D3DVERTEXELEMENT9.Offset to get to an individual element. D3DVERTEXELEMENT9.Type will tell you what type it is. There is only a handful so you could switch/case on that (and cast e.g. to D3DVECTOR or D3DCOLOR). Edited by unbird

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