R3 Draw - Shape Sub-Commands

	Contents
Concept Arc Close Curv Curve Hline Line Move Qcurv Qcurve Vline

See also:

• R3 View - Graphics Draw Dialect
• R3 Draw - Setup and Attribute Commands
• R3 Draw - Line Related Commands
• R3 Draw - Curve Related Commands

Concept

This section describes special commands optimized for describing shapes. All of these commands are used withing the shape argument block and should not be used separately.

Arc

Draws an elliptical arc from the current point.

Argument	Datatype	Description
end-point	pair!
radius-x	decimal!
radius-y	decimal!
angle	decimal!
sweep	word!	the arc will be drawn in a "positive angle" direction sweep
large	word!	one of the large arc sweeps will be chosen large

Simple arc example:

pen yellow
line-width 3
shape [
    move 100x200
    arc 300x200 120 50 0
]

Set SWEEP to draw arcs in a "positive-angle" direction:

pen yellow
line-width 3
shape [
    move 100x200
    arc 300x200 120 50 0 sweep
]

Set LARGE for arc sweeps greater than 180 degrees:

pen yellow
line-width 3
shape [
    move 100x200
    arc 300x200 120 50 0 sweep large
]

More complex usage of arc:

pen yellow
line-width 3
shape [
    move 0x399
    line 42x357
    arc 84x315 25 20 -45 sweep
    line 126x273
    arc  168x231 25 40 -45 sweep
    line 210x189
    arc  252x147 25 60 -45 sweep
    line 294x105
    arc  336x63 25 80 -45 sweep
    line 399x0
    move 0x0
]

Same complex example but with relative positioning commands:

pen red
line-width 3
translate 0x399
shape [
    move 0x0
    'line 42x-42
    'arc 42x-42 25 20 -45 sweep
    'line 42x-42
    'arc 42x-42 25 40 -45 sweep
    'line 42x-42
    'arc 42x-42 25 60 -45 sweep
    'line 42x-42
    'arc 42x-42 25 80 -45 sweep
    'line 63x-63
    move 0x0
]

Close

Closes previously defined set of lines in the SHAPE block.

This command has no arguments.

In some case it is easier to use the CLOSE command as a shortcut instead of calculating the closing lines.

This is without CLOSE commands:

line-width 3
pen yellow
shape [
    move 100x100
    hline 50
    arc 100x50 50 50 0 large
    move 75x75 vline 25 arc 25x75 50 50 0
    move 0x160
    line 200x160 200x0 0x0
]

And here with CLOSE commands:

line-width 3
pen yellow
shape [
    move 100x100
    hline 50
    arc 100x50 50 50 0 large
    close
    move 75x75 vline 25 arc 25x75 50 50 0
    close
    move 0x160
    line 200x160 200x0 0x0
]

Curv

Smooth CURVE command shortcut.

Argument	Datatype	Description
point1	pair!
point2	pair!
point1	pair!
...	pair!

From http://www.w3.org/TR/SVG11/paths.html:

"The first control point is assumed to be the reflection of the second control point on the previous command relative to the current point. (If there is no previous curve command, the first control point is the current point.)"

Simple example:

line-width 3
pen yellow
shape [
    move 100x50
    vline 150
    curv 300x150 300x50
    move 0x0
]

Same example but with relative positioning commands:

line-width 3
pen red
shape [
    'move 100x50
    'vline 100
    'curv 200x0 200x-100
    move 0x0
]

Curve

Draws a cubic Bézier curve.

Argument	Datatype	Description
point1	pair!
point2	pair!
point3	pair!
point4	pair!
...	pair!

A cubic Bézier curve is defined by a start point, an end point, and two control points.

line-width 3
pen yellow
shape [
    move 100x50
    curve 100x150 300x150 300x50
    move 0x0
]

Same example but with relative positioning commands:

line-width 3
pen red
shape [
    move 100x50 'curve 0x100 200x100 200x0
    move 0x0
]

Hline

Draws a horizontal line from the current point.

Argument	Datatype	Description
end-x	decimal!

Using absolute coordinates:

pen yellow
line-width 4
shape [
    move 100x100
    hline 300
    move 100x150
    hline 250
    move 100x200
    hline 200
]

Using relative coordinates:

pen red
line-width 4
shape [
    move 100x100
    'hline 200
    'move -200x50
    'hline 150
    'move -150x50
    'hline 100
]

Line

Draws a line from the current point through the given points, the last of which becomes the new current point.

Argument	Datatype	Description
point1	pair!
point2	pair!
point3	pair!
point4	pair!
...	pair!

Using absolute coordinates:

pen yellow
line-width 4
shape [
    move 50x50
    line 300x120 50x120 300x50
    move 0x0
]

Using relative coordinates:

pen red
line-width 4
shape [
    move 50x50
    move 50x50 'line 250x70 -250x0 250x-70
    move 0x0
]

Move

Set's the starting point for a new path without drawing anything.

Argument	Datatype	Description
point1	pair!

The effect is as if the "pen" were lifted and moved to a new location.

Used at the end of a SHAPE command, MOVE prevents the shape from being drawn as a closed polygon.

Note: Every path defined in SHAPE block is automatically closed. To disable the auto-close feature just put at the end of the SHAPE block: move 0x0

line-width 4
pen red
shape [
    move 100x100
    line 20x20 150x50
    move 0x0
]
pen blue
shape [
    move 100x200
    line 20x120 150x150
]

Using relative coordinates for the second shape:

line-width 4
pen red
shape [
    move 100x100
    line 20x20 150x50
    move 0x0
]
pen blue
shape [
    move 100x100
    'move 0x100
    'line -80x-80 130x30
    'move 0x0
]

Qcurv

Smooth QCURVE command shortcut.

Argument	Datatype	Description
point1	pair!

Draws a cubic Bézier curve from the current point to point1.

See: http://www.w3.org/TR/SVG11/paths.html and CURV

Using absolute coordinates:

pen yellow
line-width 4
shape [
    move 0x150
    qcurve 100x250 200x150
    qcurv 400x150
    move 0x0
]

Using relative coordinates:

pen red
line-width 4
shape [
    move 0x150
    'qcurve 100x100 200x0
    'qcurv 200x0
    move 0x0
]

Qcurve

Draws quadratic Bézier curve.

Argument	Datatype	Description
point1	pair!
point2	pair!
point3	pair!
...	pair!

A quadratic Bézier curve is defined by a start point, an end point, and one control point.

Using absolute coordinates:

pen yellow
line-width 4
shape [
    move 100x50
    qcurve 200x150 300x50
    move 0x0
]

Using relative coordinates:

pen red
line-width 4
shape [
    move 100x50
    'qcurve 100x100 200x0
    move 0x0
]

Vline

Draws a vertical line from the current point.

Argument	Datatype	Description
end-y	decimal!

Using absolute coordinates:

pen yellow
line-width 4
shape [
    move 100x100  vline 300
    move 150x100  vline 250
    move 200x100  vline 200
]

Using relative coordinates:

pen red
line-width 4
shape [
    move 100x100   'vline 200
    'move 50x-200  'vline 150
    'move 50x-150  'vline 100
]