Appendix 3 : Complete list of plot codes

Graphics commands such as MOVE, DRAW, RECTANGLE etc. are actually special types of PLOT command. The PLOT keyword is followed by three numbers. The first is the action code and the other two are the x and y coordinates.

The action code is formed by adding two numbers together. The first of these refers to the type of object being produced, e.g. drawing a line, filling a triangle etc. and the second one refers to the way in which the object is put on the screen:

Code	Action
0	Solid line with both end points
8	Solid line without final end point
16	Dotted line with both end points
24	Dotted line without final end point
32	Solid line without starting point
40	Solid line without either end point
48	Dotted line without starting point, continuing pattern
56	Dotted line without either end point, continuing pattern
64	Plot a single point
72	Draw a line to left and right of point until a non-background colour is reached
80	Fill a triangle, using given and previous two sets of coordinates
88	Draw a line to the right of the point until the background colour is reached
96	Draw a filled rectangle
104	Draw a line to left and right of point until the foreground colour is reached
112	Draw and fill a parallelogram
120	Draw a line to the right of the point until a non-foreground colour is reached
128	Flood fill around the point until a non-background colour is reached
136	Flood fill around the point until the foreground colour is reached
144	Draw a circle
152	Draw and fill a circle
160	Draw a circular arc
168	Draw a segment
176	Draw a sector
184	Move or copy a rectangular portion of the screen
192	Draw an ellipse
200	Draw and fill an ellipse
208	Used with fonts
216	Reserved for future use
224	Reserved for future use
232	Plot a sprite
240	Used by user programs
248	Used by user programs

The second number is added to the first one and describes how the object is plotted on the screen. These numbers are not used for moving or copying rectangles (action codes 184 - 191):

Code	Effect
0	Move graphics cursor relative to the last point
1	Plot relative to the last point using the graphics foreground colour
2	Plot relative to the last point using the inverse of the graphics foreground colour
3	Plot relative to the last point using the graphics background colour
4	Move graphics cursor to the coordinates given
5	Plot at the coordinates given using the graphics foreground colour
6	Plot at the coordinates given using the inverse of the graphics foreground colour
7	Plot at the coordinates given using the graphics background colour

PLOT action codes 184 - 191, which move and copy rectangular portions of the screen, are slightly different:

Code	Action
184	Move graphics cursor relative to the last point
185	Move a rectangle relative to the last point
186	Copy a rectangle relative to the last point
187	Copy a rectangle relative to the last point
188	Move graphics cursor to the coordinates given
189	Move a rectangle to the coordinates given
190	Copy a rectangle to the coordinates given
191	Copy a rectangle to the coordinates given

The PLOT command only includes one set of coordinates but a shape has several points which all need to be specified. This is done by 'visiting' one or two points with the graphics cursor and specifying a further one in the PLOT command:

• To draw a line, MOVE to one end and PLOT 5, specifying the other end.
• A triangle is filled by a MOVE to two points and PLOT 85, specifying the third.
• A rectangle is filled by a MOVE to one corner and PLOT 101, specifying the opposite corner.
• A parallelogram is filled by a MOVE to two adjacent corners and PLOT 117, specifying the corner opposite the first one visited.
• A circle is drawn or filled by a MOVE to its centre and PLOT 149 or 157, specifying a point on the circle.
• An arc, segment or sector is drawn by a MOVE to the centre of its circle, another MOVE to the clockwise end and PLOT 165, 173 or 181, specifying the anticlockwise end.
• An ellipse is drawn or filled by a MOVE to its centre followed by a MOVE to where the ellipse passes above or below the centre and PLOT 197 or 205, specifying the highest or lowest point of the ellipse.