The thing with how rendering work is that a "complex UI" vs a "single control" will use the same and only rendering feature required, aka: "render triangle list given a scissoring rectangle". There's no middle ground.
I will provide an example app that use glScissor() and the fixed pipeline so no custom shaders will be required. However I am not sure how the performance will behave with widgets that frequently change the clipping rectangle. At the moment the system is optimised to minimize draw calls (I would like a typical "complex" tool to take under 0.5/1.0 milliseconds to build and render). I was actually considering moving the clipping rectangle within the vertex buffer so everything could be rendered in 1 draw call, which would simplify the code and be faster, but requires a custom shader. That is to say, it is an open ended problem and there's not one single solution.
I already pushed some tweaks and comments in the sample applications. Your criticism is perfectly legit and I aiming to simplify integration as much as possible so please don't hesitate to comment further if you had another go at it.
I will provide an example app that use glScissor() and the fixed pipeline so no custom shaders will be required. However I am not sure how the performance will behave with widgets that frequently change the clipping rectangle. At the moment the system is optimised to minimize draw calls (I would like a typical "complex" tool to take under 0.5/1.0 milliseconds to build and render). I was actually considering moving the clipping rectangle within the vertex buffer so everything could be rendered in 1 draw call, which would simplify the code and be faster, but requires a custom shader. That is to say, it is an open ended problem and there's not one single solution.
I already pushed some tweaks and comments in the sample applications. Your criticism is perfectly legit and I aiming to simplify integration as much as possible so please don't hesitate to comment further if you had another go at it.