Trouble getting VBOs to work

After a good few hours of reading and trying, I still can’t get VBOs to work. Below are relevant parts of the code, but the code was made in C# using Tao Framework(OpenGl library). keyword “out” means the same as & in C++, and (IntPtr)x is the equivalent of (char *)NULL + x.


Gl.glClearColor(0, 0, 0, 0.5f);

Gl.glViewport(0, 0, width, height);


Gl.glFrustum(-1, 1, -1, 1, 1, 1000);

float[] a = new float[16] {-1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0}; //first 3 floats - coors, last 4 - color
float[] b = new float[16] {0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0}; // 16 floats in a single vertex = 64 Bytes
float[] c = new float[16] {1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0};

int [] VerticeIndice = new int[3] {0,1,2} //3 ints = 12 bytes

//VBOs creating

Gl.glGenBuffers(1, out VBOadress);
Gl.glBindBuffer(Gl.GL_ARRAY_BUFFER, VBOadress);
Gl.glBufferData(Gl.GL_ARRAY_BUFFER, (IntPtr)192, null, Gl.GL_STATIC_DRAW);

Gl.glBufferSubData(Gl.GL_ARRAY_BUFFER, (IntPtr)0, (IntPtr)64, a);
Gl.glBufferSubData(Gl.GL_ARRAY_BUFFER, (IntPtr)64, (IntPtr)64, b);
Gl.glBufferSubData(Gl.GL_ARRAY_BUFFER, (IntPtr)128, (IntPtr)64, c);

Gl.glGenBuffers(1, out IVBOadress);
Gl.glBindBuffer(Gl.GL_ELEMENT_ARRAY_BUFFER, IVBOadress);
Gl.glBufferData(Gl.GL_ELEMENT_ARRAY_BUFFER, (IntPtr)12, null, Gl.GL_STATIC_DRAW);

Gl.glBufferSubData(Gl.GL_ELEMENT_ARRAY_BUFFER, (IntPtr)0, (IntPtr)12, VerticeIndice);



Gl.glTranslatef(0, 0, -10);


Gl.glBindBuffer(Gl.GL_ARRAY_BUFFER, VBOadress);

Gl.glVertexPointer(3, Gl.GL_FLOAT, 64, (IntPtr)0);
Gl.glColorPointer(4, Gl.GL_FLOAT, 64, (IntPtr)12);

Gl.glBindBuffer(Gl.GL_ELEMENT_ARRAY_BUFFER, IVBOadress);

Gl.glDrawElements(Gl.GL_TRIANGLES, 3, Gl.GL_UNSIGNED_INT, (IntPtr)0);



The code produces a black screen - nothing get’s drawn.
Thanks in advance;)

You have to be careful about the order you enable client states in, and AFAIK should minimize calls to glVertexPointer as that’s the one that actually does a lot of configuration prior to drawing.

Also GL_INDEX_ARRAY is not what you think it is! :wink:

Below is an iPhone tutorial, but it’s basically the same for your purposes, just don’t use the OES extensions, use the ones you are using already: I simply found it a nice clear and concise tutorial which I stumbled on by accident when I was looking for details on the glMapBuffer extension for the iPhone.

Here’s another tutorial for you…

Looking at your code above, specifically the data at the top, it doesn’t look like there is much there to draw though… Perhaps I am missing something but your geometry doesn’t look right, and the colour data is strange…

Thank you very much,
without “Gl.glEnableClientState(Gl.GL_INDEX_ARRAY);”(which I didn’t even write in the above text, but it was there alright) it works like charm. It probably somehow set the color to (0,0,0).

The data is alrght;) A tri color triangle.

This leads me to another question - I’ve read that “glvertexpointer”(and similar) and “glenablestate” are deprecated. How do I make it work without them?

Look no further but here to see how it’s done, you may also check out the tutorial on VAO in the same site.

Thanks! Great tutorials - very helpfull, and just what I’ve been looking for. It’s damn hard to find up to date material. When are you planning to release part 3?:wink:

in a week or so i hope