The best way to send data to OpenGL is through something called Vertex Buffer Objects.īasically these are OpenGL objects that store buffers of vertex data for you.

We now have all the information we need, we just need to pass it to OpenGL! Creating Vertex Buffer Objects

an array that gives a list of triangles to create, by specifying the 3 vertices that make up each triangle.

an array with all the info for each vertex.

a structure to keep track of all our per-vertex information (currently just color and position).

Open up HelloGLKitViewController.m and create a plain old C-structure and a few arrays to keep track of our square information, as shown below: One of the nice things about OpenGL ES 2.0 is you can keep your vertex data organized in whatever manner you like.

However we can create a square with two triangles as you can see in the picture above: one triangle with vertices (0, 1, 2), and one triangle with vertices (2, 3, 0). When you render geometry with OpenGL, keep in mind that it can’t render squares – it can only render triangles. The square will be set up like the following: Let’s start things nice and simple by rendering a square to the screen. OK, time to draw something to the screen with OpenGL! This tutorial continues where the last one left off, so if you haven’t done it already complete the previous tutorial first. And then we’ll use some of the new handy functions in the GLKMath library to make it rotate around! In this second and final part of the tutorial, now that you know the basics we can get to the fun stuff! We’ll use some OpenGL commands and a new GLKit class called GLKBaseEffect to render a square to the screen. In the process, you learned all about what these classes can do for you, and why you’d want to use them. In the first part of the series, we showed you how to create a simple GLKView and GLKViewController based project from scratch. Welcome back to our Beginning OpenGL ES 2.0 with GLKit series! Note from Ray: This is the fifth iOS 5 tutorial in the iOS 5 Feast! This tutorial is a free preview chapter from our new book iOS 5 By Tutorials.

Opengl es 2.0 drawelements line