Tyr: Textures and Shaders
There was no blog post last week, sorry about that, but truthfully I’d not really done enough to justify one, it was a week of research more than coding, but I did find the answers to some questions (mostly about efficient sprite rendering).
So, this week I decided to take a bit of a break from the Asset Manager, and take the time to actually implement textures properly, loading the compiled textures and sending the image data off to OpenGL turned out to be rather easy, OpenGL supports rendering DXT compressed textures via the ‘ubiquitous’ GL_COMPRESSED_RGBA_S3TC etc. extentions, these aren’t part of the official spec, but being labelled as ‘ubiquitous’ means that most hardware supports them, so I decided it was safe to use them.
I then moved on to dragging my sprite renderer slightly into the modern era by switching from ye-olde fixed-function rendering to using shaders, I created a simple sprite vertex and fragment shader (it’s about 4 lines long) that basically just replaces what the fixed-function version did (render a texture, multiplied by a colour, at positions specified by the vertices).
I’d never set-up shaders in OpenGL before, and a fair amount of the documentation I found used the ARB extentions to load and compile the shaders, howver, combining a few different websites (mainly this one) I managed to come up with a solution that works.
In the process of attempting to get shaders working, I made much use of my logger class, and have extended it so that, when asserts are enabled, it will trigger a break-point whenever it logs an ‘Error’ or ‘Fatal’ level message.
I’m having fun working on the main engine again, so I’ll likely not work on the Asset Manager this week, instead I want to attempt to make it easier to move, rotate and scale sprites around the small test scene I’m making.
Tags: C++, OpenGL, Tyr