So far I determined that my largest brush texture causes performance to drop after 2500 vertices have been drawn with it, and my smallest texture can go 110000 vertices. I have implemented a scheme where the verts are calculated after every draw, and if they exceed these predetermined numbers (using a percentage of max verts), I put all the elements on screen into a backup array, take a UIImage snapshot of the canvas, clear the canvas, and then display the snapshot on a UIImageView which sits just below the metal view. Since the metal canvas is now empty, performance is maintained. I feel this is a horrible solution but it is the only thing my mediocre coding brain could come up with. The UIImage snapshot displays a little darker than the metal view, so when the change happens, there's a noticeable jarring switch. It works, but it's ugly. I wish I knew how the Procreate developers are able to maintain such solid and smooth performance in their drawing app. I'm open to suggestions on how to better handle this scenario.

Thank you! Yes I am calling draw(index)Primitives. I will work on the offscreen texture method, this is extremely helpful for me.

I just realized I could copy the newly resized drawing into a new view. I would delete my question if I could.

Ohhhh, okay. I had not considered the fragment shaders or kernel. I will study and work on those. The effect I want is to be able to paint over dark colors with light colors and still have the dark colors show through. Currently my light colors are completely opaque and cover the dark colors when painting over them. So to prevent banding, what would be a better pixel format to use?

I may be a bit naive, MoreLighnting, on the subject you are referring to. First I accept that I am probably only 10% there with my app. I have a grand idea for it, but I know deep down that I need a developer who can rewrite the entire thing and make it shine because my coding skills are not that great. There are too many things I just don't understand. So for now if I can get it working and doing everything that I need it to, then at least I have a working prototype that I can then hand over to an experienced and qualified professional to make it what it needs to be. That is my hope. I have been stashing away money for this very purpose. Finding a developer though for me is a scary process. But that will be my next step. As for my naivety, what I mean by that is I have never heard of health issues related to the Apple Pencil. What are those issues? It is something that has never crossed my mind. I am an artist by trade and have been very happy with the iPad Pro and Apple Pencil. Can you elaborate?