OpenGLES3.2 features

[Brian Beuken]

Now 3.0 and 3.1 gave us a lot of new stuctures and buffers to use making it really quite on a par with OpenGL itself. 
There was also an impressive Extension pack for 3.1 which was available only for Android

However those Android only features were then wrapped into OpenGLES3.2 as standard features and this has allowed OpenGLES to continue with its alightment of OpenGL by adding few very impressive extra features including two new shader types


Tessellation shaders
Geometry shaders
Now some OpenGLES3.1 boards do have Geometry and Tesselation shaders as extensions (Tinkerboard for example) but thats just because they have the Android Extension Pack. Its safer to only attempt Geometry and Tessellation on a full 3.2 board in Linux, but probably safe if you are coding in Android.


These don't in themselves give you any extra power, in fact they can be quite a cost on framerates if you over use them, but they do allow you to greatly enhance the detail of your graphics from reasonably simple basic model types. 

Tessellation shaders (they come in a pair) in particular, really need a massivly powerful GPU, but when used well can create wonderful Levels of Detail in our models, but I confess I find using them to be overcomplex and combersome, running a few tests on a very simple PC GPU card shows significant slow down, I havn't tried to build anything on an SBC, but I imagine the frame rates would plummet. But for fairly static screens, not requireing real time updates like menus you can turn simple models into things of beauty.
Here's some info on Tessellation shaders...prepare for a brain melting.. 
http://ogldev.atspace.co.uk/www/tutorial...ial30.html


Geometry shaders however used sparingly can do some really cool things, and my favourite OpenGL tutorial site has a great demo on how to use them.
https://learnopengl.com/Advanced-OpenGL/Geometry-Shader


There's also more advanced texture types, ability to work with compressed textures reducing our footprint,  new blending capabilties and mutlisampling added as well as (praise the coding gods) some debug features which really start to be needed as all these extra features can make a shader chain much more prone to bugs.

As with OpenGLES3.1 though we must be aware that we have very very feeble GPU's on an SBC, and just becuase they can do something, does not mean its wise to do it. In the same way as per pixel shading looks amazing, don't expect 60fps updates if every model uses it. Likewise Tesselation and Geometry shaders can greatly enhance the visual effect of your project with little effort on the coding side, it all takes up processing cycles and can slow things down.

But we dont' care do we
Even though its been out a couple of years now, there really are not many devices using it yet, Only high end phones and tablets, but developers are are still mostly targetting 2.0 and 3.0 as base level systems due to teh market share they present.

So with only a few devices, there's not a lot of demo's out there to show the real power of the new shaders... I llike to refer to the ARM developer site for tutorials and explinations, well more explinations than tutorials.

However do remember what I said about OpenGLES3.2 being more complient with OpenGL, if you check out some OpenGL4.0+ demos you'll certainly get some ideas of how to use GLES3.2 in anger.

https://developer.arm.com/docs/100587/la...engl-es-32