Avoiding .toArray() with DX vertex buffers in C#

Uh... any reason why your VB isn't just an Array to begin with?

Uh... any reason why your VB isn't just an Array to begin with?

Well the VertexBuffer and corresponding index buffer are what im using to create a DirectX mesh which i thought was right?

As for the actual vertexdata, i am using a list instead of an array as the length is continuously changing and i am constantly manipulating the data.

Thanks

Use an array as the above poster suggests. Using a list, then converting that to an array is verryyyy bad. The fact that the size changes doesn't mean you should use a list, nor does the fact that you modify the contents. Just make sure the array is big enough to hold the data, modify the array, then set your vertex buffers.

Use an array as the above poster suggests. Using a list, then converting that to an array is verryyyy bad. The fact that the size changes doesn't mean you should use a list, nor does the fact that you modify the contents. Just make sure the array is big enough to hold the data, modify the array, then set your vertex buffers.

Ok i see so its just best to stick with an array then? That sucks as i was enjoying the functions of lists and didn't want to have to keep iteratively clearing the arrays and repopulating them...

The VB itself does accept the lists and compiles but throws an error - "Operation is not valid due to the current state of the object". But i guess there isn't a way around this.

Cheers

don't clear the array. Just make sure there is enough space available for what ever operation you are going to do, and then work on the array.

You really don't need to shrink it either if the size does not vary much, i.e. by 10k is nothing on modern computers, so it is better to simply leave the extra space at the end unused because you might use it on the next iteration.

working on arrays is MUCH faster than on lists.

don't clear the array. Just make sure there is enough space available for what ever operation you are going to do, and then work on the array.

You really don't need to shrink it either if the size does not vary much, i.e. by 10k is nothing on modern computers, so it is better to simply leave the extra space at the end unused because you might use it on the next iteration.

working on arrays is MUCH faster than on lists.

Ok thanks for this. I have been using the profiler quite a lot am realising all my programming flaws one by one. The problems i am having are not necessarily speed just memory at this stage.

Cheers

lists consume more memory as well compared to arrays

this is for the C++ list ( Edited due to the post below correcting me)
If you have a list with 500 elements, each element being a 3 component position, the total size used to store in a list on a 32 bit machine is
4 * 2* 500 * 12 = 48,000 bytes
64 bit machine 8 * 2* 500 * 12 = 96,000 bytes

The 32 version of an array's size is 4 + 200 * 12 = 2,404 bytes
The 64 version of an array's size is 8 + 200 * 12 = 2,408 bytes

So, linked lists are not only slower, but also consume alot more memory because of the two pointers held per node.
Lists are generally used if there are alot of insertions and removals from random locations.

The C# Base Class Library List is a dynamically resizable array (a vector).

You are right.... Ok OK So the above post is good for c++ then. I learn something new every day.

Wow I never realised it was that much memory usage. No wonder i am running out of memory ... I use a lot of lists as I thought I was being clever...!

Those numbers were for c++, not c#. it was an error on my part.

ok so i have one more cheeky question. While you were very right in terms of the efficiency of Arrays over lists, i tried switching the following code:

_catmullShellMesh = [color="blue"]new [color="#2b91af"]Mesh(_meshIBCounter, _meshVBCounter, [color="#2b91af"]MeshFlags.Managed, [color="#2b91af"]CustomVertex.[color="#2b91af"]PositionColored.Format, _DXDevice);
_catmullShellMesh.VertexBuffer.SetData(_colouredCatmulltVertices.ToArray(), 0, [color="#2b91af"]LockFlags.Discard);
_catmullShellMesh.IndexBuffer.SetData(_catmullIndexArray.ToArray(), 0, [color="#2b91af"]LockFlags.Discard);
to this
_catmullShellMesh = [color="blue"]new [color="#2b91af"]Mesh(_meshIBCounter, _meshVBCounter, [color="#2b91af"]MeshFlags.Managed, [color="#2b91af"]CustomVertex.[color="#2b91af"]PositionColored.Format, _DXDevice);
_catmullShellMesh.VertexBuffer.SetData(_catmullVertexData, 0, [color="#2b91af"]LockFlags.Discard);
_catmullShellMesh.IndexBuffer.SetData(_catmullIndexData, 0, [color="#2b91af"]LockFlags.Discard);


But the code only works when i specify the exact right size for the vertexdata array and the index buffer array. So obviously when i oversize the arrays it doesnt work.
Now obviously if i oversize the first two terms in creating the mesh, it will work but old data that is not overwritten is displayed. Or am i just being stupid and making a big mistake?