OpenSCAD User Manual/Transformations
Basic conceptEdit
Transformations affect their child nodes and as the name implies transform them in various ways such as moving, rotating or scaling the child. Transformations are written before the object they affect e.g.
translate([10,20,30])
cube(10);
Notice that there is no semicolon following transformation command. Transformations can be applied to a group of child nodes by using '{' and '}' to enclose the subtree e.g.
translate([0,0,5])
{
cube(10);
cylinder(r=5,h=10);
}
Cascading transformations are used to apply a variety of transforms to a final child. Cascading is achieved by nesting statements e.g.
rotate([45,45,45])
translate([10,20,30])
cube(10);
Combining transformations is a sequential process, going from right to left. Consider the following two transformations:
color("red") translate([0,10,0]) rotate([45,0,0]) cube(5);
color("green") rotate([45,0,0]) translate([0,10,0]) cube(5);
While these contain the same operations, the first will rotate a cube around the origin and then move it by the offset specified for the translate, before finally coloring it red. By contrast, the second sequence first moves a cube, and then rotates it around the origin, before coloring it green. In this case the rotation causes the cube to move along an arc centered at the origin. The radius of this arc is the distance from the origin, which was set by the preceding translation. The different ordering of the rotate and translate transformations causes the cubes to end up in different places.
Advanced conceptEdit
As OpenSCAD uses different libraries to implement capabilities this can introduce some inconsistencies to the F5 preview behaviour of transformations. Traditional transforms (translate, rotate, scale, mirror & multimatrix) are performed using OpenGL in preview, while other more advanced transforms, such as resize, perform a CGAL operation, behaving like a CSG operation affecting the underlying object, not just transforming it. In particular this can affect the display of modifier characters, specifically "#" and "%", where the highlight may not display intuitively, such as highlighting the preresized object, but highlighting the postscaled object.
scaleEdit
Scales its child elements using the specified vector. The argument name is optional.
Usage Example: scale(v = [x, y, z]) { ... }
cube(10);
translate([15,0,0]) scale([0.5,1,2]) cube(10);
resizeEdit
Modifies the size of the child object to match the given x,y, and z.
resize() is a CGAL operation, and like others such as render() operates with full geometry, so even in preview this takes time to process.
Usage Example:
// resize the sphere to extend 30 in x, 60 in y, and 10 in the z directions.
resize(newsize=[30,60,10]) sphere(r=10);
If x,y, or z is 0 then that dimension is left asis.
// resize the 1x1x1 cube to 2x2x1
resize([2,2,0]) cube();
If the 'auto' parameter is set to true, it autoscales any 0dimensions to match. For example.
// resize the 1x2x0.5 cube to 7x14x3.5
resize([7,0,0], auto=true) cube([1,2,0.5]);
The 'auto' parameter can also be used if you only wish to autoscale a single dimension, and leave the other asis.
// resize to 10x8x1. Note that the z dimension is left alone.
resize([10,0,0], auto=[true,true,false]) cube([5,4,1]);
rotateEdit
Rotates its child 'a' degrees about the axis of the coordinate system or around an arbitrary axis. The argument names are optional if the arguments are given in the same order as specified.
//Usage:
rotate(a = deg_a, v = [x, y, z]) { ... }
// or
rotate(deg_a, [x, y, z]) { ... }
rotate(a = [deg_x, deg_y, deg_z]) { ... }
rotate([deg_x, deg_y, deg_z]) { ... }
The 'a' argument (deg_a) can be an array, as expressed in the later usage above; when deg_a is an array, the 'v' argument is ignored. Where 'a' specifies multiple axes then the rotation is applied in the following order: x then y then z. That means the code:
rotate(a=[ax,ay,az]) {...}
is equivalent to:
rotate(a=[0,0,az]) rotate(a=[0,ay,0]) rotate(a=[ax,0,0]) {...}
The optional argument 'v' is a vector and allows you to set an arbitrary axis about which the object is rotated.
For example, to flip an object upsidedown, you can rotate your object 180 degrees around the 'y' axis.
rotate(a=[0,180,0]) { ... }
This is frequently simplified to
rotate([0,180,0]) { ... }
When specifying a single axis the 'v' argument allows you to specify which axis is the basis for rotation. For example, the equivalent to the above, to rotate just around y
rotate(a=180, v=[0,1,0]) { ... }
When specifying a single axis, 'v' is a vector defining an arbitrary axis for rotation; this is different from the multiple axis above. For example, rotate your object 45 degrees around the axis defined by the vector [1,1,0],
rotate(a=45, v=[1,1,0]) { ... }
Rotate with a single scalar argument rotates around the Z axis. This is useful in 2D contexts where that is the only axis for rotation. For example:
rotate(45) square(10);
Rotation rule helpEdit
For the case of:
rotate([a, b, c]) { ... };
"a" is a rotation about the X axis, from the +Y axis, toward the +Z axis.
"b" is a rotation about the Y axis, from the +Z axis, toward the +X axis.
"c" is a rotation about the Z axis, from the +X axis, toward the +Y axis.
These are all cases of the Right Hand Rule. Point your right thumb along the positive axis, your fingers show the direction of rotation.
Thus if "a" is fixed to zero, and "b" and "c" are manipulated appropriately, this is the spherical coordinate system.
So, to construct a cylinder from the origin to some other point (x,y,z):
x= 10; y = 10; z = 10; // point coordinates of end of cylinder
length = norm([x,y,z]); // radial distance
b = acos(z/length); // inclination angle
c = atan2(y,x); // azimuthal angle
rotate([0, b, c])
cylinder(h=length, r=0.5);
%cube([x,y,z]); // corner of cube should coincide with end of cylinder
translateEdit
Translates (moves) its child elements along the specified vector. The argument name is optional.
Example: translate(v = [x, y, z]) { ... }
cube(2,center = true);
translate([5,0,0])
sphere(1,center = true);
mirrorEdit
Transforms the child element to a mirror of the original, as if it were the mirror image seen through a plane intersecting the origin. The argument to mirror() is the normal vector of the originintersecting mirror plane used, meaning the vector coming perpendicularly out of the plane. Each coordinate of the original object is altered such that it becomes equidistant on the other side of this plane from the closest point on the plane. For example, mirror([1,0,0]), corresponding to a normal vector pointing in the xaxis direction, will produce an object such that all positive x coordinates become negative x coordinates, and all negative x coordinates become positive x coordinates.
Function signature:Edit
mirror(v= [x, y, z] ) { ... }
ExamplesEdit
The original is on the right side. Note that mirror doesn't make a copy. Like rotate and scale, it changes the object.
rotate([0,0,10]) cube([3,2,1]); mirror([1,0,0]) translate([1,0,0]) rotate([0,0,10]) cube([3,2,1]);
multmatrixEdit
Multiplies the geometry of all child elements with the given affine transformation matrix, where the matrix is 4×3  a vector of 3 row vectors with 4 elements each, or a 4×4 matrix with the 4th row always forced to [0,0,0,1].
Usage: multmatrix(m = [...]) { ... }
This is a breakdown of what you can do with the independent elements in the matrix (for the first three rows):
[Scale X]  [Shear X along Y]  [Shear X along Z]  [Translate X] 
[Shear Y along X]  [Scale Y]  [Shear Y along Z]  [Translate Y] 
[Shear Z along X]  [Shear Z along Y]  [Scale Z]  [Translate Z] 
The fourth row is forced to [0,0,0,1] and can be omitted unless you are combining matrices before passing to multmatrix, as it is not processed in OpenSCAD. Each matrix operates on the points of the given geometry as if each vertex is a 4 element vector consisting of a 3D vector with an implicit 1 as its 4th element, such as v=[x, y, z, 1]. The role of the implicit fourth row of m is to preserve the implicit 1 in the 4th element of the vectors, permitting the translations to work. The operation of multmatrix therefore performs m*v for each vertex v. Any elements (other than the 4th row) not specified in m are treated as zeros.
This example rotates by 45 degrees in the XY plane and translates by [10,20,30], i.e. the same as translate([10,20,30]) rotate([0,0,45]) would do.
angle=45;
multmatrix(m = [ [cos(angle), sin(angle), 0, 10],
[sin(angle), cos(angle), 0, 20],
[ 0, 0, 1, 30],
[ 0, 0, 0, 1]
]) union() {
cylinder(r=10.0,h=10,center=false);
cube(size=[10,10,10],center=false);
}
The following example demonstrates combining affine transformation matrices by matrix multiplication, producing in the final version a transformation equivalent to rotate([0, 35, 0]) translate([40, 0, 0]) Obj();. Note that the signs on the sin function appear to be in a different order than the above example, because the positive one must be ordered as x into y, y into z, z into x for the rotation angles to correspond to rotation about the other axis in a righthanded coordinate system.
y_ang=35;
mrot_y = [ [ cos(y_ang), 0, sin(y_ang), 0],
[ 0, 1, 0, 0],
[sin(y_ang), 0, cos(y_ang), 0],
[ 0, 0, 0, 1]
];
mtrans_x = [ [1, 0, 0, 40],
[0, 1, 0, 0],
[0, 0, 1, 0],
[0, 0, 0, 1]
];
module Obj() {
cylinder(r=10.0,h=10,center=false);
cube(size=[10,10,10],center=false);
}
echo(mrot_y*mtrans_x);
Obj();
multmatrix(mtrans_x) Obj();
multmatrix(mrot_y * mtrans_x) Obj();
This example skews a model, which is not possible with the other transformations.
M = [ [ 1 , 0 , 0 , 0 ],
[ 0 , 1 , 0.7, 0 ], // The "0.7" is the skew value; pushed along the y axis as z changes.
[ 0 , 0 , 1 , 0 ],
[ 0 , 0 , 0 , 1 ] ] ;
multmatrix(M) { union() {
cylinder(r=10.0,h=10,center=false);
cube(size=[10,10,10],center=false);
} }
This example shows how a vector is transformed with a multmatrix vector, like this all points in a point array (polygon) can be transformed sequentially. Vector (v) is transformed with a rotation matrix (m), resulting in a new vector (vtrans) which is now rotated and is moving the cube along a circular path radius=v around the z axis without rotating the cube.
angle=45;
m=[
[cos(angle), sin(angle), 0, 0],
[sin(angle), cos(angle), 0, 0],
[ 0, 0, 1, 0]
];
v=[10,0,0];
vm=concat(v,[1]); // need to add [1]
vtrans=m*vm;
echo(vtrans);
translate(vtrans)cube();
More?Edit
Learn more about it here:
colorEdit
Displays the child elements using the specified RGB color + alpha value. This is only used for the F5 preview as CGAL and STL (F6) do not currently support color. The alpha value defaults to 1.0 (opaque) if not specified.
Function signature:Edit
color( c = [r, g, b, a] ) { ... } color( c = [r, g, b], alpha = 1.0 ) { ... } color( "#hexvalue" ) { ... } color( "colorname", 1.0 ) { ... }
Note that the r, g, b, a
values are limited to floating point values in the range [0,1] rather than the more traditional integers { 0 ... 255 }. However, nothing prevents you to using R, G, B
values from {0 ... 255} with appropriate scaling: color([ R/255, G/255, B/255 ]) { ... }
[Note: Requires version 2011.12]
Colors can also be defined by name (case insensitive). For example, to create a red sphere, you can write color("red") sphere(5);
. Alpha is specified as an extra parameter for named colors: color("Blue",0.5) cube(5);
[Note: Requires version 2019.05]
Hex values can be given in 4 formats, #rgb
, #rgba
, #rrggbb
and #rrggbbaa
. If the alpha value is given in both the hex value and as separate alpha parameter, the alpha parameter takes precedence.
Warning: alpha processing (transparency) is ordersensitive. Transparent objects must be listed after nontransparent objects to display them correctly. Some combinations involving multiple transparent objects cannot be handled correctly. See issue #1390.
The available color names are taken from the World Wide Web consortium's SVG color list. A chart of the color names is as follows,
(note that both spellings of grey/gray including slategrey/slategray etc are valid):





ExampleEdit
Here's a code fragment that draws a wavy multicolor object
for(i=[0:36]) {
for(j=[0:36]) {
color( [0.5+sin(10*i)/2, 0.5+sin(10*j)/2, 0.5+sin(10*(i+j))/2] )
translate( [i, j, 0] )
cube( size = [1, 1, 11+10*cos(10*i)*sin(10*j)] );
}
}
↗ Being that 1<=sin(x)<=1 then 0<=(1/2 + sin(x)/2)<=1 , allowing for the RGB components assigned to color to remain within the [0,1] interval.
Chart based on "Web Colors" from Wikipedia
Example 2Edit
In cases where you want to optionally set a color based on a parameter you can use the following trick:
module myModule(withColors=false) {
c=withColors?"red":undef;
color(c) circle(r=10);
}
Setting the colorname to undef keeps the default colors.
offsetEdit
[Note: Requires version 2015.03]
Offset generates a new 2d interior or exterior outline from an existing outline. There are two modes of operation. radial and offset. The offset method creates a new outline whose sides are a fixed distance outer (delta > 0) or inner (delta < 0) from the original outline. The radial method creates a new outline as if a circle of some radius is rotated around the exterior (r>0) or interior (r<0) original outline.
The construction methods can either produce an outline that is interior or exterior to the original outline. For exterior outlines the corners can be given an optional chamfer.
Offset is useful for making thin walls by subtracting a negativeoffset construction from the original, or the original from a Positive offset construction.
Offset can be used to simulate some common solid modeling operations:
 Fillet: offset(r=3) offset(delta=+3) rounds all inside (concave) corners, and leaves flat walls unchanged. However, holes less than 2*r in diameter vanish.
 Round: offset(r=+3) offset(delta=3) rounds all outside (convex) corners, and leaves flat walls unchanged. However, walls less than 2*r thick vanish.
 Parameters
 r
 Double. Amount to offset the polygon. When negative, the polygon is offset inward. R specifies the radius of the circle that is rotated about the outline, either inside or outside. This mode produces rounded corners.
 delta
 Double. Amount to offset the polygon. Delta specifies the distance of the new outline from the original outline, and therefore reproduces angled corners. When negative, the polygon is offset inward. No inward perimeter is generated in places where the perimeter would cross itself.
 chamfer
 Boolean. (default false) When using the delta parameter, this flag defines if edges should be chamfered (cut off with a straight line) or not (extended to their intersection).
Examples
// Example 1
linear_extrude(height = 60, twist = 90, slices = 60) {
difference() {
offset(r = 10) {
square(20, center = true);
}
offset(r = 8) {
square(20, center = true);
}
}
}
// Example 2
module fillet(r) {
offset(r = r) {
offset(delta = r) {
children();
}
}
}
fillEdit
[Note: Requires version Development snapshot]
Fill removes holes from polygons without changing the outline. For convex polygons the result is identical to hull().
Examples
// Example 1
t = "OpenSCAD";
linear_extrude(15) {
text(t, 50);
}
color("darkslategray") {
linear_extrude(2) {
offset(4) {
fill() {
text(t, 50);
}
}
}
}
minkowskiEdit
Displays the minkowski sum of child nodes.
Usage example:
Say you have a flat box, and you want a rounded edge. There are multiple ways to do this (for example, see hull below), but minkowski is elegant. Take your box, and a cylinder:
$fn=50;
cube([10,10,1]);
cylinder(r=2,h=1);
Then, do a minkowski sum of them (note that the outer dimensions of the box are now 10+2+2 = 14 units by 14 units by 2 units high as the heights of the objects are summed):
$fn=50;
minkowski()
{
cube([10,10,1]);
cylinder(r=2,h=1);
}
NB: The origin of the second object is used for the addition. The following minkowski sums are different: the first expands the original cube by +1 in x, +x, y, +y from cylinder, expand 0.5 units in both z, +z from cylinder. The second expands it by +1 in x, +x, y, +y and +z from cylinder, but expand 0 in the z from cylinder.
minkowski() {
cube([10, 10, 1]);
cylinder(1, center=true);
}
minkowski() {
cube([10, 10, 1]);
cylinder(1);
}
Warning: for high values of $fn the minkowski sum may end up consuming lots of CPU and memory, since it has to combine every child node of each element with all the nodes of each other element. So if for example $fn=100 and you combine two cylinders, then it does not just perform 200 operations as with two independent cylinders, but 100*100 = 10000 operations.
hullEdit
Displays the convex hull of child nodes.
Usage example:
hull() {
translate([15,10,0]) circle(10);
circle(10);
}
The Hull of 2D objects uses their projections (shadows) on the xy plane, and produces a result on the xy plane. Their Zheight is not used in the operation.
A note on limitations: Running hull() { a(); b(); }
is the same as hull() { hull() a(); hull() b(); }
so unless you accept/want hull() a();
and hull() b();
, the result will not match expectations.