CHAPTER XI - Linear Movements and Fairings

Abstract

This chapter discusses linear movements and fairings. The figures required for setting on the machine's counters and handwheels can only be arrived at by a process of calculation. There are many types of movement that are required from time to time in animation, and for some of them, the calculations of positions for successive frames involves relatively advanced mathematics. For the commonest type of movement in animation is one at a constant speed, that is, one in which the quantity involved increases or decreases by the same amount every frame. Such movements are termed linear because if the quantity for each frame is plotted against the frame number, it can result in a straight line. However, the movement need not necessarily be in a straight line, though it often is. The calculations of successive positions in a purely linear movement are easy. If the initial position is subtracted from the final position and the result is divided by the number of frames in the movement, this can give the move for each frame.