CIGAL Reference Manual, Chapter 2 (Commands): LINE
usage: LINE [ color v1 v2 width flag ]
or LINE [ color x1 y1 x2 y2 width flag]
LINE draws a line on the display screen by generating a pair of graphics vectors. The line is drawn between two endpoints which can be specified either by vector arguments (eg., V1 and V2) or by explicitly indicating their X and Y coordinates (eg., X1 Y1 and X2 Y2). If you don't specify arguments for either endpoint, then LINE will expect you to provide that endpoint by moving the cursor. For example, if you just enter:
then the command will wait for you to position the cursor and press a button for the first point and then again for the second, and will then draw a line of intensity 100 between those two points.
If COLOR is not specified it defaults to the current value of the internal variable LCOLOR. Similarly, WIDTH defaults to the current value of LCOLOR.
The FLAG argument controls various LINE options:
1 draw shape in absolute coordinates (ignoring transformation and clipping settings). 2 don't store vectors in VECS (assumed if FLAG & 1). 4 store lines or surfaces as individual vectors to facilitate transformations (ignored if FLAG & 3). 8 paint inside of shape. 16 XOR values rather than replacing them. 32 combine explicit options with default values (which depend on current program status -- see below)
The default value for FLAG depends on whether it is being called during as active SKETCH session (via a menu command). If so, FLAG defaults to 0, otherwise the default value is 2.
Vectors drawn with LINE are entered into the list of active graphics display vectors, VECS. If you have used ROTATE, SCALE, or OFFSET on this vector list you may find that the line drawn is transformed accordingly and therefore may not appear at the screen positions you expect.
BOX(2), CIRCLE(2), ELLIPSE(2), LCOLOR(4), LWIDTH(4), SKETCH(2), VECS(4)