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hannesh's picture

AccessViolationException

Posted Friday, 4 February, 2011 - 17:30 by hannesh in

I have been really careful to store everything server side, but I still get these very rare AccessViolationExceptions when I call DrawArrays (it can take minutes before it happens).

I'm using vertex array objects;

            GL.GenVertexArrays(1, out VAOid);
            GL.GenBuffers(1, out VBOid);
            GL.BindVertexArray(VAOid);
            GL.BindBuffer(BufferTarget.ArrayBuffer, VBOid);
            SetVertexPointers();
 
            GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(n * myVertex.SizeInBytes), vertices, BufferUsageHint.DynamicDraw);
            GL.BindVertexArray(0);
            vertices = null;

And to draw:

            GL.BindVertexArray(VAOid);
             GL.DrawArrays(BeginMode.Quads, 0, VertexTypeOffsets[VertexTypeOffsets.Length - 2]);
            GL.BindVertexArray(0);

Is it alright to set my client side vertex array to null and let the garbage collecter clean it up straight after GL.BufferData?
What else can cause AccessViolationExceptions?

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the Fiddler's picture

Re: AccessViolationException

Posted Friday, 4 February, 2011 - 18:07 by the Fiddler

The client-side vertex array isn't touched again once GL.BufferData returns.

AccessViolationExceptions typically indicate out-of-bounds accesses. Make sure your 'count' parameters are within bounds (e.g. in GL.DrawArrays) and that you disable any vertex attributes (vertex pointers) you are not using whenever you bind a different vertex array. If you use GL.DrawElements, make sure that all offsets are within bounds.

OpenTK can catch a number of bugs if you run it in debug mode (open OpenTK.sln, compile in "Debug" configuration and copy the resulting OpenTK.dll to your project).