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Beginner QuadTree & Index/Vertex Buffer question

Started by Tutukun Mar 21, 2007 at 4:19 PM 3 replies 1.6k views

Original Post

Mar 21, 2007 at 4:19 PM

Hi, I've been playing around with Geomipmap and Quadtree(for LOD). And I've noticed that Geomipmap only works if the heightfield size is 2^n + 1. So my 1st question is: -Does Quadtree has this same limitation? My 2nd question: -When does Vertex/Index Buffer is placed in the memory? After the CreateIndex/VertexBuffer() call or after the first Lock()&Unlock() calls? If it's the first case(after the CreateIndex/VertexBuffer() call) then: - How does the system insert data into buffers if they were created with the Read-only flag?. Thanks for looking :) Cheers :D

VerMan

Mar 21, 2007 at 4:36 PM

You fill the vertex buffer with a call to Lock(), it's the same... the READONLY flag promises the driver that your application will not attempt to add data to it. It's mainly used for performance issues.

JohnBolton

Mar 21, 2007 at 4:48 PM

Quote:
Original post by Tutukun
Hi,
I've been playing around with Geomipmap and Quadtree(for LOD). And I've noticed that Geomipmap only works if the heightfield size is 2^n + 1. So my 1st question is:

-Does Quadtree has this same limitation?

It is not required to have this limitation. In fact, the meshes don't even have to be grids. On the other hand, making the size 2ⁿ+1 helps when it comes to issues such as joining adjacent patches and LOD transitions (geomorphing, for example.)

Tutukun

Mar 21, 2007 at 5:03 PM

Quote:
Original post by VerMan
You fill the vertex buffer with a call to Lock(), it's the same... the READONLY flag promises the driver that your application will not attempt to add data to it. It's mainly used for performance issues.

what about index buffer? is it the same as vertex buffer?

Cheers

Quote:
It is not required to have this limitation. In fact, the meshes don't even have to be grids. On the other hand, making the size 2n+1 helps when it comes to issues such as joining adjacent patches and LOD transitions (geomorphing, for example.)

So you mean for size that is not 2^n+1 Quadtree is harder to do than the one for 2^n+1 size?

Thanks :)

[Edited by - Tutukun on March 23, 2007 7:03:50 AM]

Tutukun

Mar 23, 2007 at 7:05 AM

Bump
Could anyone answer my questions? :D

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