VAO support for instanced drawing. about opengl4csharp

[giawa]

I don't have an immediate solution, but do have some questions that might help arrive at a solution that we're both happy with.

1. What do you think of having a class specifically for VBOs that will support instanced rendering (could inherit VBO to continue to be supported by existing VAO code)? Something like public class InstancedVBO<T>? Or, if it makes more sense to put this in the VAO, something similar?
2. What do you think of initializing VBO with a Divisor property that defaults to 0 and must be set non-zero to be able to render as instanced? The VAO draw function could check for the Divisor being non-zero and throw an error in the appropriate situation.
3. What do you think of making the divisor a more specific constructor of the VBO. So you could simply add the new constructor public VBO(T[] Data, int Position, int Length, uint Divisor, BufferTarget Target = BufferTarget.ArrayBuffer, BufferUsageHint Hint = BufferUsageHint.StaticDraw) and require the developer include position and length values.

[TheAIBot]

To support instanced drawing, each VBO needs a divisor. It's only a single uint so i think making a whole new class for it is a bit overkill. There isn't any reason why a VBO used for instanced drawing couldn't also be used for non-instanced drawing. The difference between those two is primarily which draw call is used.

I quite like 2 and 3 but i am not sure which one is the best.
You are right that there is more ways to make the divisor more distint in the constructor.
Maybe adding it to the constructor but with a default argument like this.
public VBO(T[] Data, int Length, BufferTarget Target = BufferTarget.ArrayBuffer, BufferUsageHint Hint = BufferUsageHint.StaticDraw, uint Divisor = 0)
Would be easy enough to do and there would be no need to duplicate constructors just to add the divisor. The user can always get access to the divisor if needed and default values are provided for the preceding arguments if the user doesn't care for them.

I will make a pr with this way. If it doesn't work out like we would like then it's easy to change.

[giawa]

I think that method is fine. I'll accept the pull request once the code review is complete. Thanks!