That particular code is idiomatic to anyone who worked with 2D bitmap graphics in that era.
pt == point, r == rect, h, v == horizontal, vertical, BSR(...,1) is a fast integer divide by 2, ORD4 promotes an expression to an unsigned 4 byte integer
The algorithms are extremely common for 2D graphics programming. The first is to find the center of a 2D rectangle, the second offsets a point by half the size, the third clips a point to be in the range of a rectangle, and so on.
Converting the idiomatic math into non-idiomatic words would not be an improvement in clarity in this case.
(Mac Pascal didn't have macros or inline expressions, so inline expressions like this were the way to go for performance.)
It's like using i,j,k for loop indexes, or x,y,z for graphics axis.
pt == point, r == rect, h, v == horizontal, vertical, BSR(...,1) is a fast integer divide by 2, ORD4 promotes an expression to an unsigned 4 byte integer
The algorithms are extremely common for 2D graphics programming. The first is to find the center of a 2D rectangle, the second offsets a point by half the size, the third clips a point to be in the range of a rectangle, and so on.
Converting the idiomatic math into non-idiomatic words would not be an improvement in clarity in this case.
(Mac Pascal didn't have macros or inline expressions, so inline expressions like this were the way to go for performance.)
It's like using i,j,k for loop indexes, or x,y,z for graphics axis.