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How to Update a vertex buffer?


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#1 LetsMakeSomeNoise   Members   -  Reputation: 234

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Posted 05 February 2014 - 11:54 AM

HI,I'm a beginner to D3D11

the msdn says there are 16 input slots (0-15) and each buffer must be assigned to different slot.

Is that means i can only create 16 vertex buffers?

or i can create many buffers and several buffers can be bound to single input slot?

 

Oh,what I'm actually want to do is to manage the vertice of  several meshes  ,and I'm forming the class
 MESH with C++ on VS2010,in a DLL  ,so the vertex data will be unpredictable (and the data will not be obtained until the EXE pass in)

So i should update the global vertex buffer using some kind of method.(I create the Vertex Buffer with Default usage,noCpuAcess,NULL to the init SubresourceData), And there's an global array of vertex in system memory like g_VertexInSysMem[1000],every time adding new vertices will fill part of the array.

 

Is that UpdateResource enough for updating???

i want to know if following code is enough:

 

D3D11_SUBRESOURCE_DATA updateVertexData;

updateVertexData.pSysMem = g_VertexInSysMem;

 g_pImmediateContext->UpdateSubresource(g_pVertexBuffer,0,NULL,&updateVertexData,0,0);

 

HELP!!! I CAN'T DRAW EVEN A TRIANGLE!!



#2 kauna   Crossbones+   -  Reputation: 2918

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Posted 05 February 2014 - 12:57 PM

- No, you may create as many buffers as you require (however, typically it is advisable to keep the number of buffers small), 16 inputs slots mean that you can have 16 unique buffers binded as shader resources during one draw call. 

 

- You can use UpdateSubresource or Map / Unmap to update a vertex buffer content. You may have static vertex buffers (update very rarely) or dynamic vertex buffers (update more often). Their usage patterns differ. 

 

- Start simple and look in to D3D examples that come with the SDK. You'll find simple examples to draw even a single triangle. 

 

Cheers!


Edited by kauna, 05 February 2014 - 03:56 PM.


#3 LetsMakeSomeNoise   Members   -  Reputation: 234

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Posted 05 February 2014 - 10:37 PM

- No, you may create as many buffers as you require (however, typically it is advisable to keep the number of buffers small), 16 inputs slots mean that you can have 16 unique buffers binded as shader resources during one draw call. 

 

- You can use UpdateSubresource or Map / Unmap to update a vertex buffer content. You may have static vertex buffers (update very rarely) or dynamic vertex buffers (update more often). Their usage patterns differ. 

 

- Start simple and look in to D3D examples that come with the SDK. You'll find simple examples to draw even a single triangle. 

 

Cheers!

thanks!! btw,if i want to use multiple vertex buffers, can i IAsetVertexBuffers with different buffers to Input slot 0 ?(before a draw call)



#4 InfinityMachine   Members   -  Reputation: 238

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Posted 06 February 2014 - 01:13 PM

 

- No, you may create as many buffers as you require (however, typically it is advisable to keep the number of buffers small), 16 inputs slots mean that you can have 16 unique buffers binded as shader resources during one draw call. 

 

- You can use UpdateSubresource or Map / Unmap to update a vertex buffer content. You may have static vertex buffers (update very rarely) or dynamic vertex buffers (update more often). Their usage patterns differ. 

 

- Start simple and look in to D3D examples that come with the SDK. You'll find simple examples to draw even a single triangle. 

 

Cheers!

thanks!! btw,if i want to use multiple vertex buffers, can i IAsetVertexBuffers with different buffers to Input slot 0 ?(before a draw call)

 

 

Hey I ran into a similar issue and found a small excerpt which may help.

http://books.google.com/books?id=AyACb-t8E-MC&pg=PA124&lpg=PA124&dq=IASetIndexBuffer&source=bl&ots=I7c5w6sdBZ&sig=d7ymxuLpfqkfUTFzvz4zHlAiOZo&hl=en&sa=X&ei=8bfzUpDkDKPMsQSW4YDoAg&ved=0CHQQ6AEwCA#v=onepage&q=IASetIndexBuffer&f=false


Find yourself. If you can't, keep looking.


#5 kauna   Crossbones+   -  Reputation: 2918

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Posted 06 February 2014 - 03:08 PM


thanks!! btw,if i want to use multiple vertex buffers, can i IAsetVertexBuffers with different buffers to Input slot 0 ?(before a draw call)

 

Your question could almost be understood in 2 ways:

 

- Multiple vertex buffers at same time (during one draw call), you'll bind each buffer to a separate input slot. The vertex buffer slots must be in accord to the Input Slot defined in the input layouts (check D3D11_INPUT_ELEMENT_DESC).

 

- Otherwise, you would bind the vertex buffer which contains the data needed for drawing to the Slot 0 (if it is the slot you have defined in the Input Layout). Typically before each draw call you'll need to bind a vertex buffer. Consider it as an optimization to check if the vertex buffer is already bound.

 

Cheers!






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