(Added lower accuracy and more lines, hopefully speeding up the engine and NOT crashing scratch. There is also a reason I ask for you to use turbowarp, most pentros are ran there anyways.) (For backgrounds, I'd recommend a different way to clip it as linear interpolation across hundreds of pixels at least 20 times per frame can turn the process to thousands of computations per frame, which will almost guarantee a crash on scratch. If you want to know the logic and how I would fix this for backgrounds specifically, you can ask me in the comments.) Please open on turbowarp for best experience. After learning about circles in math a couple years ago, this has become really trivial. I've created simple line clipping that checks for distance to the radius, and if it's inside the bounds, it won't work. Ik this is really appreciated in the intro community so here's a resource you can use. Please credit. For usage: simply create circles with the custom block, and my code will do the work for you.
