I am slowly moving my project from tao to opentk. I was using Gl.gldrawArrays (Gl.GL_TRIANGLES, 0, size), and that worked with tao. When I switched to opentk, that won't work. I tried to change all of tao calls to opentk ( GL.DrawArrays(BeginMode.Triangles, 0, size ); ...), but it won't work. It just draws empty background (clear) color. I had two scenes in my program, in the first one, there was about 500FPS (FRAPS), and in the other about 160FPS. I was switching between those scenes with a keyboard. When I start my program fps is about 550 (maybe because opentk is faster than tao?), and when i switch the 2nd scene it is about 200, so it is taking some time to render more complicated 2nd scene. I have tried few texture loading snippets that i found here, I think that loading textures works. Please help.