7.3 KiB
Basic Shapes Tutorial
Primitives
There are 5 built-in primitive shapes that OpenSCAD provides.
square(), circle(), cube(), cylinder(), and sphere().
The BOSL2 library extends or provides alternative to these shapes so
that they support more features, and more ways to simply reorient them.
2D Squares
You can still use the built-in square() in the familiar ways that OpenSCAD provides:
square(100, center=false);
square(100, center=true);
square([60,40], center=true);
The BOSL2 library provides an enhanced equivalent to square() called rect().
You can use it in the same way you use square(), but it also provides
extended functionality. For example, it allows you to round the corners:
rect([60,40], center=true, rounding=10);
Or chamfer them:
rect([60,40], center=true, chamfer=10);
You can even specify which corners get rounded or chamferred. If you pass a
list of four size numbers to the rounding= or chamfer= arguments, it will
give each corner its own size. In order, it goes from the back-right (quadrant I)
corner, counter-clockwise around to the back-left (quadrant II) corner, to the
forward-left (quadrant III) corner, to the forward-right (quadrant IV) corner:
module text3d(text) text(
text=text, font="Times", size=10,
halign="center", valign="center"
);
translate([ 50, 50]) text3d("I");
translate([-50, 50]) text3d("II");
translate([-50,-50]) text3d("III");
translate([ 50,-50]) text3d("IV");
rect([90,80], center=true);
If a size is given as 0, then there is no rounding and/or chamfering for
that quadrant's corner:
rect([60,40], center=true, rounding=[0,5,10,15]);
rect([60,40], center=true, chamfer=[0,5,10,15]);
You can give both rounding= and chamfer= arguments to mix rounding and
chamfering, but only if you specify per corner. If you want a rounding in
a corner, specify a 0 chamfer for that corner, and vice versa:
rect([60,40], center=true, rounding=[5,0,10,0], chamfer=[0,5,0,15]);
Anchors and Spin
Another way that rect() is enhanced over square(), is that you can anchor,
spin and attach it.
The anchor= argument is an alternative to center=, which allows more
alignment options. It takes a vector as a value, pointing roughly towards
the side or corner you want to align to the origin. For example, to align
the center of the back edge to the origin, set the anchor to [0,1]:
rect([60,40], anchor=[0,1]);
To align the front right corner to the origin:
rect([60,40], anchor=[1,-1]);
To center:
rect([60,40], anchor=[0,0]);
To make it clearer when giving vectors, there are several standard vector constants defined:
| Constant | Direction | Value |
|---|---|---|
LEFT |
X- | [-1,0,0] |
RIGHT |
X+ | [1,0,0] |
FRONT/FORWARD/FWD |
Y- | [0,-1,0] |
BACK |
Y+ | [0,1,0] |
BOTTOM/BOT/BTM/DOWN |
Z- | [0,0,-1] (3D only.) |
TOP/UP |
Z+ | [0,0,1] (3D only.) |
CENTER/CTR |
Centered | [0,0,0] |
Note that even though these are 3D vectors, you can use most of them,
(except UP/DOWN, of course) for anchors in 2D shapes:
rect([60,40], anchor=BACK);
rect([60,40], anchor=CENTER);
You can add vectors together to point to corners:
rect([60,40], anchor=FRONT+RIGHT);
Finally, the spin argument can rotate the shape by a given number of degrees
clockwise:
rect([60,40], anchor=CENTER, spin=30);
Anchoring or centering is performed before the spin:
rect([60,40], anchor=BACK, spin=30);
2D Circles
The built-in circle() primitive can be used as expected:
circle(r=50);
circle(d=100);
circle(d=100, $fn=8);
The BOSL2 library provides an enhanced equivalent of circle() called oval().
You can use it in the same way you use circle(), but it also provides
extended functionality. For example, it allows more control over its size and
orientation.
Since a circle in OpenSCAD can only be approximated by a regular polygon with
a number of straight sides, this can lead to size and shape inaccuracies.
To counter this, the realign= and circum= arguments are also provided.
The realign= argument, if set true, rotates the oval() by half the angle
between the sides:
oval(d=100, $fn=8, realign=true);
The circum= argument, if true, makes it so that the polygon forming the
oval() circumscribes the ideal circle instead of inscribing it.
Inscribing the ideal circle:
difference() {
oval(d=100, $fn=360);
oval(d=100, $fn=8);
}
Circumscribing the ideal circle:
difference() {
oval(d=100, $fn=8, circum=true);
oval(d=100, $fn=360);
}
Another way that oval() is enhanced over circle(), is that you can anchor,
spin and attach it.
oval(r=50, anchor=BACK);
oval(r=50, anchor=FRONT+RIGHT);
Using spin on a circle may not make initial sense, until you remember that anchoring is performed before spin:
oval(r=50, anchor=FRONT, spin=30);
Enhanced 3D Cube
You can use enhanced cube() like the normal OpenSCAD built-in:
cube(100);
cube(100, center=true);
cube([50,40,20], center=true);
You can use anchor similarly to square(), except you can anchor vertically
too, in 3D, allowing anchoring to faces, edges, and corners:
cube([50,40,20], anchor=BOTTOM);
cube([50,40,20], anchor=TOP+BACK);
cube([50,40,20], anchor=TOP+FRONT+LEFT);
You can use spin as well, to rotate around the Z axis:
cube([50,40,20], anchor=FRONT, spin=30);
3D objects also gain the ability to use an extra trick with spin;
if you pass a list of [X,Y,Z] rotation angles to spin, it will
rotate by the three given axis angles, similar to using rotate():
cube([50,40,20], anchor=FRONT, spin=[15,0,30]);
3D objects also can be given an orient argument that is given as a vector,
pointing towards where the top of the shape should be rotated towards.
cube([50,40,20], orient=UP+BACK+RIGHT);
If you use anchor, spin, and orient together, the anchor is performed
first, then the spin, then the orient:
cube([50,40,20], anchor=FRONT, spin=45, orient=UP+FWD+RIGHT);
Enhanced 3D Cylinder
You can use the enhanced cylinder() as normal for OpenSCAD:
cylinder(r=50,h=50);
cylinder(r=50,h=50,center=true);
cylinder(d=100,h=50,center=true);
cylinder(d1=100,d2=80,h=50,center=true);