The behavior of a PLOT LINES statement is described using the notion of 'beams'.
The state of a beam is 'on' or 'off'. If the beam moves when it is on, it draws a line.
The beam is set to be off when a program starts.
PLOT LINES: x,ymoves the beam to (x,y), and let it off.
PLOT LINES: x,y ;moves the beam to (x,y), and let it on.
PLOT LINESlet the beam off.
PLOT LINES: x1, y1 ; x2, y2 ; ･･･ ; xn , yndraws the polygonal line through the points specified, and then let the beam off.
The beam shall be off on the following.
(1) Before executing of any other PLOT or GRAPH statement than PLOT LINES.
(2) Before executing of any GET, LOCATE, MAT PLOT, MAT GRAPH, MAT GET, or MAT LOCARE statement.
(3) Before executing of SET WINDOW, SET VIEWPORT, SET DEVICE WINDOW, or SET DEVICE VIEWPORT.
(4) Before and after the invocation of a PICTURE definition.
SET LINE COLOR numeric_expression
sets the color index that is used for line plotting.
The default line color is 1.
SET LINE STYLE numeric_expression
sets the line style that is used for line plotitng.
The line styles are
1 for solid, 2 for dashed, 3 for dotted, 4 for dashed-dotted.
The default line style is 1.
ASK LINE COLOR Numeric_Variable
assigns the current line color.
ASK LINE STYLE Numeric_Variable
assigns the current line style.
ASK MAX LINE STYLE Numeric_Variable
assigns the largest line style, 4 on this version.
PLOT BEZIER: x1, y1 ; x2, y2 ; x3, y3; x4, y4
draws a Bézier curve of terminal points (x1, y1)，(x4, y4), and control points (x2 , y2), (x3, y3).
SET LINE WIDTH numeric_expression
assigns the line width multiplier to the normal width.
On Windows 95/98/Me, if line width is 2 or more, the line style is ignored.
SET BEAM MODE "IMMORTAL"
The beam shall remain on the execution of any GET, LOCATE, GRAPH or PLOT statement except PLOT LINES, or on any invocation of a PICTURE definition.
SET BEAM MODE "RIGOROUS"
The beam shall be off according to the Full BASIC standard.
ASK LINE WIDTH n
substitute n with the current line width.
ASK BEAM MODE s$
substitute s$ with the current beam mode.