OpenGL ES 2D Drawing Performance Estimation

Question

I've been confronted with the extremely bad drawing Performance of Quartz/Core Graphics.

I don't believe its bad in every scenario, but in my occasion, where i need to redraw something like 3000 short lines frequently, it performs super bad.

Since the Modal (of MVC) is fixed I can not change how it spits out the data (if I could, i would have followed the advice, to only draw the changes, so the lines dont have to be redrawn every frame).

So as a conclusion I am considering using opengl for that purpose and I would like to ask u (experienced) guys for an estimation of how well it could work using opengl, before starting to work into that topic, as it seems by far more difficult than Quartz.

Answer 1

You almost certainly see a speed performance lift from OpenGL over Quartz, however remember that whereas Quartz uses point to point drawing, OpenGL is based on the use of vertices and vertices points (essentially co-ordinates). You may find you need to do some mid-weight parsing work on your existing data source to re-work it into this vertices point system.

Also keep in mind that drawing text on top of an OpenGL ES object is a tricky task - it can be done (ironically) by using Quartz to generate an image, and then using this image as a texture.

I'd definitely recommend using OpenGL Kit as it will make life a bit easier for you as a beginner to OpenGL. Ray Wenderlich has an excellent starting point tutorial here :

http://www.raywenderlich.com/5223/beginning-opengl-es-2-0-with-glkit-part-1