Line drawing preliminaries

Basic Math Review

Cartesian Coordinate System

Slope-Intercept Formula For A Line

Given a third point on the line : P = (X,Y)

Slope = ( Y - Y1 ) / ( X - X1 ) = ( Y2 - Y1 ) / ( X2 - X1 )

Solving For Y

Y = [ (Y2-Y1) / (X2-X1)]X + [-(Y2-Y1)/(X2-X1)]X1 + Y1

or

Y = mx + b