変数名とか略記
http://d.hatena.ne.jp/ABA/20080314#p2
min, minimum
max, maximum
mul, multiply
div, division
num, number
util, utility
spec, specification
pos, position
vel, velocity
deg, degree
rect, rectangle
geom, geometry
rand, random
cnt, counter
dist, distance
dir, direction
idx, index
思いついたものを追加していく
ctx, context
vec, vector
