Temporary NotesΒΆ

This needs to be restructured into actual docs.

  • Shaders and textures can be easily loaded by using the get_texture and get_shader method inherited from Effect.
  • The cube objects is a VAO that you bind supplying the shader and the system will figure out the attribute mapping.
  • Please look in the demosys.opengl.geometry module for the valid attribute names and look at shaders in the testdemo.
  • You currently define vertex, fragment and geometry shader in one glsl file separated by preprocessors.
  • Effects not defined in the settings.py module will not run.

That should give you an idea..

Anything we draw to the screen must be implemented as an Effect. If that effect is one or multiple things is entirely up to you. An effect is an individual package/directory containing an effect.py module. This package can also contain a shaders and textures directory that demosys will automatically find and load resources from. See the testdemo.

Explore the testdemo project, and you’ll get the point.

Some babble about the current state of the project:

  • All geometry must be defined using VAOs. There’s a very convenient VAO class for this already making it quick and easy to create them. Look at the demosys.opengl.geometry module for examples.
  • We support vertex, fragment and geometry shaders for now. A program must currently be written in one single .glsl file separating the shaders with preprocessors. See existing shaders in testdemo.
  • The Shader class will inspect the linked shader and cache all attributes and uniforms in local dictionaries. This means all uniform*-setters use the name of the uniform instead of the location. Location is resolved internally in the object/class.
  • The VAOs bind(..) requires you to pass in a shader. This is because the VAO will automatically adapt to the attributes in your shader. During the VAO creation you need to make the name mapping to the attribute name. If you have a VAO with positions, normals, uvs and tangents and pass in a shader that only use position (or any other combination of attributes in the VAO); the VAO class will on-the-fly generate a version internally with only positions.
  • We only support 2D textures at the moment loaded with PIL/Pillow, but this is trivial to extend.
  • Resource loading is supported in the Effect class itself. In __init__() you can fetch resources using for example self.get_shader orself.get_texture. This will return a lazy object that will be populated after the loading stage is done.
  • Resources shared between effects can be put outside effect packages inside your project directory. For example in testdemo/resources/shaders and testdemo/resources/textures. Make sure you add those paths in the settings file.
  • We don’t have any scene/mesh loaders. You can hack something in yourself for now or just stick to or extend the geometry module. - We try to do as much validation as possible and give useful feedback when something goes wrong.
  • The time value passed to the effects draw method is the current duration in the playing music. If no music is loaded, a dummy timer is used.