Vulkan/metal/d3d give you control to do things you could not do with OpenGL, and they are very similar. All my code works first in Vulkan and Metal, but d3d is

Vulkan/metal/d3d give you control to do things you could not do with OpenGL, and they are very similar. All my code works first in Vulkan and Metal, but d3d is not hard when you have your vulkan code working. OpenGL was designed by committee and politics(like not giving you the option to compile shaders for a long time while d3d could do it). The hard part is thinking in term extreme parallelism. That is super hard. Once you have something working in the GPU, you can translate it to electronics like using FPGAs. The difference in efficiency is so big, that most GPU approaches do not really work. They are really approximations that fail with certain glyphs. Designers create a model that works with most glyphs, and sometimes they have a fallback, inefficient method for them. With the CPU you can calculate the area under a pixel exactly.