other than computers graphic and models are there mnemonic devices that was used to memorize alot of designs so you can draw them correctly from memory and any perspective?

also devices to help you animate correctly without softwares so you can sort of perform animation correctly whether walking or trotting in balance, limping, complete with mathemathically correct weight?

in fact how would you describe mathemathically correct, realistic animation's physics, especially walks and runs, trots, so that the limbs either move in turns or unison, as however the motion intends it to, an also to achieve realism as natural as possible?