notes from the bigfug

Yesterday was a good coding day. Rested and replete from some serious mince pie and hot chestnut ingestion the day before, I sat down and added LUA support.

For years the plan was to have the entire internal system of PB available for scripting. Previously I’ve messed about with various approaches but have settled on a hierarchical tree of named wxVariant objects.

This benefits me in three ways:

1. it’s instantly ready to be tied into OSC as the naming conventions are exactly the same
2. using wxVariant saves having lots of classes for each type
3. using the OSC addressing scheme in LUA reduces the need for a lot of class specific functions and provides a quick way to access new functionality without having to write a lot of supporting glue code

At the moment there are only global functions as I’m just using light user data so the code looks like this:

-- test_000.lua

root = pb.getroot();      -- returns the object that the script was dragged 'n' dropped on

var_alpha = pb.getchild( root, 'alpha' );

pb.setvalue( var_alpha, 0.5 );

Which is obviously pretty long winded and confusing. Have already partially written the code for using LUA objects instead but just need to make sure it’s going to be workable without introducing class dependence.

Bolstered by that success I also turned my hand to adding OpenGL shader support. I’m almost ashamed to admit I’ve not really gotten into shader programming as yet. Have been too busy pushing pixels around with the CPU, and besides I haven’t been using any visual software that supported them. Until now!

My original thinking was that shaders would act a bit like textures: you can drag and drop them onto geometry but reading up and refining my understanding of how they worked I realised there may be some interesting possibilities for not only shifting off workload to the GPU, but also expanding on the flexibility of the application.

At the moment PB supports multitexturing and the default blending modes - this is added in the code, but by moving that part into the shader, and just expanding the properties system to be able to drag and drop textures into the configuration of the shader, I can get rid of that hard coded functionality, reduce the amount of GL instructions I need to call per frame, and get much more flexibility. Sounds like a plan to me!

December 17th, 2007 | Category: Uncategorized | Subscribe to comments | Leave a comment | Trackback URL