It's appears so complicated. I tried with other shapes and things just disappear from the UI.
Can someone share a simple of example of how to have a primitive shape like a sphere show up on the UI?
So if you really want to learn this, you need to learn shader programming. There's plenty of resources online for that, just remember that in HISE you only work with FRAGMENT SHADERS, so whenever they start talking about vertex shaders or textures, you need to skip these parts.
The most complicated thing to wrap your head around at the beginning is that you need to forget how usual 2D graphics programming work. Stuff like drawCircle() or fillRect() will not be available, because the GPU is highly parallelized and needs to be able to calculate every single pixel independently. So in order to draw a circle, you need to check whether the given coordinate (that pixel you're about to render) has a smaller distance to the circle center than the radius, and in that case, you can assume it's inside the circle and draw it with the circle colour.
I suggest you head over to shadertoy.com, search for simple examples and start modifying the code to get a feeling for how it works.
