williams-et-al-1983-apple-ii-computer-graphics

100 APPLE II COMPUTER GRAPHICSWe will show you how to digitize a figure into a shape, put the shapeinto a shape table, and how to save the results of your labor. From there,you will use APPLESOFT to draw, erase, rotate, and scale your shape. Youwill see very quickly how tedious and time-consuming shapes can be ifyou do them you rself. Fortunately, for your sanity, any good Hi-Res graphicseditor will contain a provision for making shapes from the figures youdevelop on the screen, so that the machine does all the menial calculationsinstead of you. We highly recommend using a Hi-Res editor to makeshapes.Ta the Vector Belong the SpoilsTo draw a shape, the Apple II uses a series of vectors which tell it whetheror not to plot the current point; and which direction to move to find thenext point. Each vector is visually represented by a little arrow with a doton one end. (See Figure HD-1 B.) ·We will begin with a very simple figure inorder to illustrate the technique and rules for digitizing a shape. FigureHll-1 A is the block diagram of a figure which uses only three dots, andFigure 10-1 B shows the six vectors used to turn them on .•i6. 0--; _._•ABFigure 19-1.