Element buffers

This article describes how to use an element buffer for drawing.

Creating the buffer

Creating the buffer containing the array with indices is exactly the same as creating a normal vertex buffer.

unsigned short indices[] = {
	0, 1, 2,
	2, 3, 0
};
GL::VertexBuffer ebo( indices, sizeof( indices ), GL::BufferUsage::StaticDraw );

Binding an element buffer

The new vertex buffer contains the 4 corners of a quad on the Z plane now. To activate a buffer as element buffer, it has to be bound to a VertexArray object.

vao.BindElements( ebo );

As long as an element buffer is bound to a VAO, it will be used for all drawing operations involving elements with the VAO bound.

Drawing

When an element buffer has been bound to a VertexArray instance, it can be used with DrawElements as follows:

gl.DrawElements( vao, GL::Primitive::Triangles, 0, 6, GL::Type::UnsignedShort );

The type of the indices has to be explicitly specified here, it is not remembered. If you want to ignore the element buffer, simply use DrawArrays instead.