OpenSCAD User Manual/The OpenSCAD Language

The OpenSCAD Language

General

The text in its current form is incomplete.

Comments

OpenSCAD uses C++-style comments:

// This is a comment
 
myvar = 10; // The rest of the line is a comment
 
/*
    Multi-line comments
    can span multiple lines.
*/

Variables

Variables in OpenSCAD are simply a name followed by an assignment via an expression

Example:

myvar = 5 + 4;

Strings

Explicit double quotes or backslashes need to be escaped (\" and \\ respectively). Other escaped special characters are newlines (\n), tabs (\t) and carriage returns (\r).

NB! This behavior is new since OpenSCAD-2001.04. You can upgrade old files using the following sed command: sed 's/\\/\\\\/' non-escaped.scad > escaped.scad

Example:

 echo("The quick brown fox \tjumps \"over\" the lazy dog.\rThe quick brown fox.\nThe \\lazy\\ dog.");

Output:
ECHO: "The quick brown fox jumps "over" the lazy dog.
The quick brown fox.
The \lazy\ dog."

Variables are set at compile-time, not run-time

Note: Because OpenSCAD calculates its variable values at compile-time, not run-time, the last variable assignment will apply everywhere the variable is used. It may be helpful to think of them as overrideable constants rather than as variables.

Example:

 // The value of 'a' reflects only the last set value
    a = 0;
    echo(a);
 
    a = 5;
    echo(a);

Output

ECHO: 5
ECHO: 5

This behavior however is scoped to either the root or to a specific call to a module, meaning you can re-define a variable within a module without affecting its value outside of it. However, all instances within that call will behave as described above with the last-set value being used throughout.

Example:

p = 4;
test(5);
echo(p);
 
p = 6;
test(8);
echo(p);
 
module test(q)
{
    p = 2 + q;
    echo(p);
 
    p = 4 + q;
    echo(p);
}

Output

ECHO: 9
ECHO: 9
ECHO: 6
ECHO: 12
ECHO: 12
ECHO: 6

While this appears to be counter-intuitive, it allows you to do some interesting things: For instance, if you set up your shared library files to have default values defined as variables at their root level, when you include that file in your own code, you can 're-define' or override those constants by simply assigning a new value to them.

See the assign for more tightly scoped changing of values.

Getting input

Now we have variables, it would be nice to be able to get input into them instead of setting the values from code. There are a few functions to read data from DXF files, or you can set a variable with the -D switch on the command line.

Getting a point from a drawing

Getting a point is useful for reading an origin point in a 2D view in a technical drawing. The function builtin_dxf_cross will read the intersection of two lines on a layer you specify and return the intersection point. This means that the point must be given with two lines in the DXF file, and not a point entity.

OriginPoint = builtin_dxf_cross(filename="drawing.dxf", layername="SCAD.Origin", 
                                origin=[0, 0], scale=1);

Getting a dimension value

You can read dimensions from a technical drawing. This can be useful to read a rotation angle, an extrusion height, or spacing between parts. In the drawing, create a dimension that does not show the dimension value, but an identifier. To read the value, you specify this identifier from your script:

TotalWidth = builtin_dxf_dim(filename="drawing.dxf", layername="SCAD.Dims", 
                             name="TotalWidth", origin=[0, 0], scale=1);

For a nice example of both functions, see Example009 and the image on the homepage of OpenSCAD.

Conditional and Iterator Functions

For Loop

Iterate over the values in a vector or range.

Vector version: for (variable=<vector>) <do_something> - <variable> is assigned to each successive value in the vector
Range version: for (variable=<range>) <do_something>

Range: [<start>:<end>] - iterate from start to end inclusive. Also works if if <end> is smaller than <start>
Range: [<start>:<increment>:<end>] - iterate from start to end with the given increment. The increment can be a fraction Note: The increment is given as an absolute value and cannot be negative. If <end> is smaller than <start> the increment should remain unchanged.

Usage example 1 - iteration over a vector:
for (z = [-1, 1]) // two iterations, z = -1, z = 1 { translate([0, 0, z]) cube(size = 1, center = false); }	OpenSCAD iteration over a vector

Usage example 2a - iteration over a range:
for ( i = [0 : 5] ) { rotate( i * 360 / 6, [1, 0, 0]) translate([0, 10, 0]) sphere(r = 1); }	OpenSCAD iteration over a range)

Usage example 2b - iteration over a range specifying an increment:

// Note: The middle parameter in the range designation // ('0.2' in this case) is the 'increment-by' value for ( i = [0 : 0.2 : 5] ) { rotate( i * 360 / 6, [1, 0, 0]) translate([0, 10, 0]) sphere(r = 1); } } Usage example 3 - iteration over a vector of vectors (rotation): for(i = [ [ 0, 0, 0], [ 10, 20, 300], [200, 40, 57], [ 20, 88, 57] ]) { rotate(i) cube([100, 20, 20], center = true); } OpenSCAD for loop (rotation) Usage example 4 - iteration over a vector of vectors (translation): for(i = [ [ 0, 0, 0], [10, 12, 10], [20, 24, 20], [30, 36, 30], [20, 48, 40], [10, 60, 50] ]) { translate(i) cube([50, 15, 10], center = true); } OpenSCAD for loop (translation) Intersection For Loop Iterate over the values in a vector or range and take an intersection of the contents. Note: intersection_for() is a work around because of an issue that you cannot get the expected results using a combination of the standard for() and intersection() statements. Parameters <loop variable name>  Name of the variable to use within the for loop. Usage example 1 - loop over a range: intersection_for(n = [1 : 6]) { rotate([0, 0, n * 60]) { translate([5,0,0]) sphere(r=12); } } OpenSCAD Intersection for Usage example 2 - rotation : intersection_for(i = [ [ 0, 0, 0], [ 10, 20, 300], [200, 40, 57], [ 20, 88, 57] ]) { rotate(i) cube([100, 20, 20], center = true); } OpenSCAD Intersection for (rotation) If Statement Conditionally evaluate a sub-tree. Parameters The boolean expression that should be used as condition Usage example: if (x > y) { cube(size = 1, center = false); } else { cube(size = 2, center = true); } Assign Statement Set variables to a new value for a sub-tree. Parameters The variables that should be (re-)assigned Usage example: for (i = [10:50]) { assign (angle = i*360/20, distance = i*10, r = i*2) { rotate(angle, [1, 0, 0]) translate([0, distance, 0]) sphere(r = r); } } Mathematical Operators The text in its current form is incomplete. Logical Operators All logical operators take Boolean values as operands and produce a Boolean value. && Logical AND || Logical OR ! Logical NOT Relational Operators All relational operator take numbers as operands and produce a Boolean value. The equal and not-equal operators can also compare Boolean values. < less than <= less equal == equal != not equal >= greater equal > greater than Scalar Arithmetical Operators The scalar arithmetical operators take numbers as operands and produce a new number. + add - subtract * multiply / divide % modulo The "-" can also be used as prefix operator to negate a number. Vector Operators The vector operators take vectors as operands and produce a new vector; + add element-wise - subtract element-wise The "-" can also be used as prefix operator to element-wise negate a vector. Vector-Number Operators The vector-number operators take a vector and a number as operands and produce a new vector; * multiply all vector elements by number / divide all vector elements by number Conditional Operators The ?: operator can be used to conditionally evaluate one or another expression. It works like the ?: operator from the family of C-like programming languages. Example given: x>0 ? "pos" : "neg" Mathematical Functions The text in its current form is incomplete. abs Mathematical absolute value function. Returns the positive value of a signed decimal number. Usage examples: abs(-5.0); abs(0); abs(8.0); Results: 5.0 0.0 8.0 acos Mathematical arccosine, or inverse cosine, function. asin Mathematical arcsine, or inverse sine, function. atan Mathematical arctangent, or inverse tangent, function. Returns the principal value of the arc tangent of x, expressed in degrees. See: atan function atan2 Mathematical two-argument atan function. Returns the principal value of the arc tangent of y/x, expressed in degrees. See: atan2 ceil Mathematical ceiling function. See: Ceil Function cos Mathematical cosine function. Usage Examples: for(i=[0:36]) translate([i*10,0,0])cylinder(r=5,h=cos(i*10)*50+60); OpenSCAD Cos Function‎ exp Mathematical exp function. Returns the base-e exponential function of x, which is the number e raised to the power x. See: Exponent floor Mathematical floor function. See: Floor Function ln Mathematical natural logarithm. See: Natural logarithm log Mathematical logarithm. See: Logarithm lookup (Inserted by a beginner, may need fixing!) From a given key-value array, it will interpolate a value for any key using linear interpolation. Parameters key  A lookup key <key,value array>  keys and values Usage example: Will create a sort of 3D chart made out of cylinders of different height. function get_cylinder_h(p) = lookup(p, [ [ -200, 5 ], [ -50, 20 ], [ -20, 18 ], [ +80, 25 ], [ +150, 2 ] ]); for (i = [-100:5:+100]) { // echo(i, get_cylinder_h(i)); translate([ i, 0, -30 ]) cylinder(r1 = 6, r2 = 2, h = get_cylinder_h(i)*3); } OpenSCAD Lookup Function max Returns the maximum of the two parameters. Parameters <a>  Decimal. <b>  Decimal. Usage Example: max(3.0,5.0); max(8.0,3.0); Results: 5.0 8.0 min Returns the minimum of the two parameters. Parameters <a>  Decimal. <b>  Decimal. Usage Example: min(3.0,5.0); min(8.0,3.0); Results: 3.0 3.0 pow Mathematical power function. Parameters <base>  Decimal. Base. <exponent>  Decimal. Exponent. Usage examples: for (i = [0:5]) { translate([i*25,0,0]) { cylinder(h = pow(2,i)*5, r=10); echo (i, pow(2,i)); } } rands Random number generator. Parameters min_value  Minimum value of random number range max_value  Maximum value of random number range value_count  Number of random numbers to return seed_value (optional)  Seed value for random number generator for repeatable results. Usage Examples: seed=42; random_vect=rands(5,15,4,seed); echo( "Random Vector: ",random_vect); sphere(r=5); for(i=[0:3]) { rotate(360*i/4) { translate([10+random_vect[i],0,0]) sphere(r=random_vect[i]/2); } } round The "round" operator returns the greatest or least integer part, respectively, if the numeric input is positive or negative. Some examples: round(x.5) = x+1. round(x.49) = x. round(-(x.5)) = -(x+1). round(-(x.49)) = -x. sign Mathmatical signum function. Returns a unit value that extracts the sign of a value see: Signum function Parameters <x>  Decimal. Value to find the sign of. Usage examples: sign(-5.0); sign(0); sign(8.0); Results: -1.0 0.0 1.0 sin Mathematical sine function. Parameters <degrees>  Decimal. Angle in degrees. Usage example 1 for (i = [0:5]) { echo(360*i/6, sin(360*i/6)*80, cos(360*i/6)*80); translate([sin(360*i/6)*80, cos(360*i/6)*80, 0 ]) cylinder(h = 200, r=10); } Usage example 2: for(i=[0:36]) translate([i*10,0,0])cylinder(r=5,h=sin(i*10)*50+60); OpenSCAD Sin Function sqrt Mathematical square root function. Usage Examples: translate([sqrt(100),0,0])sphere(100); tan Mathematical tangent function. Parameters <degrees>  Decimal. Angle in degrees. Usage examples: for (i = [0:5]) { echo(360*i/6, tan(360*i/6)*80); translate([tan(360*i/6)*80, 0, 0 ]) cylinder(h = 200, r=10); } String Functions The text in its current form is incomplete. str Convert all arguments to strings and concatenate. Usage examples: number=2; echo ("This is ",number,3," and that's it."); echo (str("This is ",number,3," and that's it.")); Results: ECHO: "This is ", 2, 3, " and that's it." ECHO: "This is 23 and that's it." Primitive Solids The text in its current form is incomplete. cube Creates a cube at the origin of the coordinate system. When center is true the cube will be centered on the origin, otherwise it is created in the first octant. The argument names are optional if the arguments are given in the same order as specified in the parameters Parameters size  Decimal or 3 value array. If a single number is given, the result will be a cube with sides of that length. If a 3 value array is given, then the values will correspond to the lengths of the X, Y, and Z sides. Default value is 1. center  Boolean. This determines the positioning of the object. If true, object is centered at (0,0,0). Otherwise, the cube is placed in the positive quadrant with one corner at (0,0,0). Defaults to false Usage examples: cube(size = 1, center = false); cube(size = [1,2,3], center = true); sphere Creates a sphere at the origin of the coordinate system. The argument name is optional. Parameters r  Decimal. This is the radius of the sphere. The resolution of the sphere will be based on the size of the sphere and the $fa, $fs and $fn variables. For more information on these special variables look at: OpenSCAD_User_Manual/Other_Language_Features $fa  Angle in degrees $fs  Angle in mm Usage Examples sphere(r = 1); sphere(r = 5); sphere(r = 10); // this will create a high resolution sphere with a 2mm radius sphere(2, $fn=100); // will also create a 2mm high resolution sphere but this one // does not have as many small triangles on the poles of the sphere sphere(2, $fa=5, $fs=0.1); cylinder Creates a cylinder at the origin of the coordinate system. When both radii are same it is also possible to specify a single radius using the argument name r. The argument names are optional if the arguments are given in the same order as specified above. Parameters h  Decimal. This is the height of the cylinder. Default value is 1. r1  Decimal. This is the radius of the cylinder/cone on bottom end. Default value is 1. r2  Decimal. This is the radius of the cylinder/cone on top end. Default value is 1. r  Decimal. The radius of both top and bottom ends of the cylinder. Use this parameter if you want a non-cone shaped cylinder. Default value is 1. $fa  Angle in degrees $fs  Angle in mm Usage Examples cylinder(h = 10, r1 = 10, r2 = 20, center = false); cylinder(h = 10, r1 = 20, r2 = 10, center = true); cylinder(h = 10, r=20); cylinder(h = 10, r=20, $fs=6); polyhedron Usage example: polyhedron(points = [ [x, y, z], ... ], triangles = [ [p1, p2, p3..], ... ], convexity = N); Create a polyhedron with the specified points and triangles. (The 'pN' components of the triangles vector are 0-indexed references to the elements of the points vector.) convexity Integer. The convexity parameter specifies the maximum number of front sides (back sides) a ray intersecting the object might penetrate. This parameter is only needed for correctly displaying the object in OpenCSG preview mode and has no effect on the polyhedron rendering. Real Example 1: polyhedron( points=[[0,0,0],[100,0,0],[0,100,0],[0,100,100]], triangles=[[0,1,2],[1,0,3],[0,2,3],[2,1,3]] ); Real example 2 (a kind of prism, see the picture below) polyhedron ( points = [[0, -10, 60], [0, 10, 60], [0, 10, 0], [0, -10, 0], [60, -10, 60], [60, 10, 60]], triangles = [[0,3,2], [0,2,1], [3,0,4], [1,2,5], [0,5,4], [0,1,5], [5,2,4], [4,2,3], ]); A simple hand-crafted Polyhedron Note that if your polygons are not all oriented the same way OpenSCAD will either print an error or crash completely, so pay attention to the vertex ordering. e.g. polyhedron( points = [[0,0,0],[100,0,0],[0,100,0],[0,100,100]], triangles = [[0,1,2], [0,1,3], [0,2,3], [1,2,3]]); //Generates an error polyhedron( points = [[0,0,0],[100,0,0],[0,100,0],[0,100,100]], triangles = [[0,1,2], [1,0,3], [0,2,3], [2,1,3]]); //Works Let's now see how to fix polyhedrons with badly oriented polygons. When you select 'Thrown together' from the view menu and compile the design (not compile and render!) you will see a preview with the mis-oriented polygons highlighted. Unfortunately this highlighting is not possible in the OpenCSG preview mode because it would interfere with the way the OpenCSG preview mode is implemented.) Below you can see the code and the picture of such a problematic polyhedron, the bad polygons (triangles or compositions of triangles) are in pink. // Bad polyhedron polyhedron (points = [ [0, -10, 60], [0, 10, 60], [0, 10, 0], [0, -10, 0], [60, -10, 60], [60, 10, 60], [10, -10, 50], [10, 10, 50], [10, 10, 30], [10, -10, 30], [30, -10, 50], [30, 10, 50] ], triangles = [ [0,2,3], [0,1,2], [0,4,5], [0,5,1], [5,4,2], [2,4,3], [6,8,9], [6,7,8], [6,10,11], [6,11,7], [10,8,11], [10,9,8], [0,3,9], [9,0,6], [10,6, 0], [0,4,10], [3,9,10], [3,10,4], [1,7,11], [1,11,5], [1,7,8], [1,8,2], [2,8,11], [2,11,5] ] ); Polyhedron with badly oriented polygons A correct polyhedron would be the following: polyhedron (points = [ [0, -10, 60], [0, 10, 60], [0, 10, 0], [0, -10, 0], [60, -10, 60], [60, 10, 60], [10, -10, 50], [10, 10, 50], [10, 10, 30], [10, -10, 30], [30, -10, 50], [30, 10, 50] ], triangles = [ [0,3,2], [0,2,1], [4,0,5], [5,0,1], [5,2,4], [4,2,3], [6,8,9], [6,7,8], [6,10,11],[6,11,7], [10,8,11], [10,9,8], [3,0,9], [9,0,6], [10,6, 0],[0,4,10], [3,9,10], [3,10,4], [1,7,11], [1,11,5], [1,8,7], [2,8,1], [8,2,11], [5,11,2] ] ); Beginner's tip: If you don't really understand "orientation", try to identify the mis-oriented pink triangles and then permute the references to the points vectors until you get it right. E.g. in the above example, the third triangle ([0,4,5]) was wrong and we fixed it as [4,0,5]. In addition, you may select "Show Edges" from the "View Menu", print a screen capture and number both the points and the triangles. In our example, the points are annotated in black and the triangles in blue. Turn the object around and make a second copy from the back if needed. This way you can keep track. Clockwise Technique: (Noob entry, please confirm) Orientation is determined by clockwise indexing. This means that if you're looking at the triangle (in this case [4,0,5]) from the outside you'll see that the path is clockwise around the center of the face. The winding order [4,0,5] is clockwise and therefore good. The winding order [0,4,5] is counter-clockwise and therefore bad. Likewise, any other clockwise order of [4,0,5] works: [5,4,0] & [0,5,4] are good too. If you use the clockwise technique, you'll always have your faces outside (outside of OpenSCAD, other programs do use counter-clockwise as the outside though). Polyhedron with badly oriented polygons Transformations The text in its current form is incomplete. scale Scales its child elements using the specified vector. The argument name is optional. Usage Example: scale(v = [x, y, z]) { ... } rotate Rotates its child a degrees about the origin 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 above. When a rotation is specified for multiple axis' the rotation is applied in the following order: x, y, z. Usage: rotate(a = deg, v = [x, y, z]) { ... } For example, to flip an object upside-down, you might do this: rotate(a=[0,180,0]) { ... } The above example will rotate your object 180 degrees around the 'y' axis. The optional argument 'v' allows you to set an arbitrary axis about which the object will be rotated. Example with arbitrary origin. rotate(a=45, v=[1,1,0]) { ... } This example will rotate your object 45 degrees around the axis defined by the vector [1,1,0]. translate Translates (moves) its child elements along the specified vector. The argument name is optional. Usage example: translate(v = [x, y, z]) { ... } mirror Mirrors the child element on a plane through the origin. The argument to mirror() is the normal vector on that plane. Usage example: mirror([ 0, 1, 0 ]) { ... } multmatrix Multiplies the geometry of all child elements with the given 4x4 transformation matrix. Usage: multmatrix(m = [...]) { ... } Example (translates by [10, 20, 30]): multmatrix(m = [ [1, 0, 0, 10], [0, 1, 0, 20], [0, 0, 1, 30], [0, 0, 0, 1] ]) cylinder(); Example (rotates by 45 degrees in XY plane and translates by [10,20,30]): 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); } color Displays the child elements using the specified RGB color + alpha value. This is only used for the OpenCSG and Thrown Together display modes. The alpha value will default to 1.0 (opaque) if not specified. Usage example: color([r, g, b, a]) { ... } Note that the r, g, b, a values are limited to floating point values in the range { 0.0 ... 1.0 } rather than the more traditional integers { 0 ... 255 }. However you can specify the values as fractions, e.g. for R,G,B integers in {0 ... 255} you can use: color([ R/255, G/255, B/255 ]) { ... } As of the 2011.12 version, colors can also be chosen by name. For example, to create a red sphere, you can use this code: color("red") sphere(5); Alpha is also available with named colors: color("Blue",0.5) cube(5); 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: Purples Lavender Thistle Plum Violet Orchid Fuchsia Magenta MediumOrchid MediumPurple BlueViolet DarkViolet DarkOrchid DarkMagenta Purple Indigo DarkSlateBlue SlateBlue MediumSlateBlue Pinks Pink LightPink HotPink DeepPink MediumVioletRed PaleVioletRed Blues Aqua Cyan LightCyan PaleTurquoise Aquamarine Turquoise MediumTurquoise DarkTurquoise CadetBlue SteelBlue LightSteelBlue PowderBlue LightBlue SkyBlue LightSkyBlue DeepSkyBlue DodgerBlue CornflowerBlue RoyalBlue Blue MediumBlue DarkBlue Navy MidnightBlue Reds IndianRed LightCoral Salmon DarkSalmon LightSalmon Red Crimson FireBrick DarkRed Greens GreenYellow Chartreuse LawnGreen Lime LimeGreen PaleGreen LightGreen MediumSpringGreen SpringGreen MediumSeaGreen SeaGreen ForestGreen Green DarkGreen YellowGreen OliveDrab Olive DarkOliveGreen MediumAquamarine DarkSeaGreen LightSeaGreen DarkCyan Teal Oranges LightSalmon Coral Tomato OrangeRed DarkOrange Orange Yellows Gold Yellow LightYellow LemonChiffon LightGoldenrodYellow PapayaWhip Moccasin PeachPuff PaleGoldenrod Khaki DarkKhaki Browns Cornsilk BlanchedAlmond Bisque NavajoWhite Wheat BurlyWood Tan RosyBrown SandyBrown Goldenrod DarkGoldenrod Peru Chocolate SaddleBrown Sienna Brown Maroon Whites White Snow Honeydew MintCream Azure AliceBlue GhostWhite WhiteSmoke Seashell Beige OldLace FloralWhite Ivory AntiqueWhite Linen LavenderBlush MistyRose Grays Gainsboro LightGrey Silver DarkGray Gray DimGray LightSlateGray SlateGray DarkSlateGray Black Chart based on "Web Colors" from Wikipedia minkowski A box and a cylinder Minkowski sum of the box and cylinder Displays the minkowski sum of child nodes. Usage example: Say you have a flat box, and you want a rounded edge. There are many ways to do this, but minkowski is very 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: $fn=50; minkowski() { cube([10,10,1]); cylinder(r=2,h=1); } hull Two cylinders Convex hull of two cylinders Displays the convex hull of child nodes. Usage example: hull() { translate([15,10,0]) circle(10); circle(10); } CSG Modeling The text in its current form is incomplete. union Creates a union of all its child nodes. This is the sum of all children. Usage example: union() { cylinder (h = 4, r=1, center = true, $fn=100); rotate ([90,0,0]) cylinder (h = 4, r=0.9, center = true, $fn=100); } difference Subtracts the 2nd (and all further) child nodes from the first one. Usage example: difference() { cylinder (h = 4, r=1, center = true, $fn=100); rotate ([90,0,0]) cylinder (h = 4, r=0.9, center = true, $fn=100); } intersection Creates the intersection of all child nodes. This keeps the overlapping portion Usage example: intersection() { cylinder (h = 4, r=1, center = true, $fn=100); rotate ([90,0,0]) cylinder (h = 4, r=0.9, center = true, $fn=100); } render Always calculate the CSG model for this tree (even in OpenCSG preview mode). The convexity parameter specifies the maximum number of front sides (back sides) a ray intersecting the object might penetrate. This parameter is only needed for correctly displaying the object in OpenCSG preview mode and has no effect on the polyhedron rendering. Usage example: render(convexity = 1) { ... } Modifier Characters The text in its current form is incomplete. Background Modifier Ignore this subtree for the normal rendering process and draw it in transparent gray (all transformations are still applied to the nodes in this tree). Usage example: % { ... } Example code: difference() { // start objects cylinder (h = 4, r=1, center = true, $fn=100); // first object that will subtracted % rotate ([90,0,0]) cylinder (h = 4, r=0.3, center = true, $fn=100); // second object that will be subtracted % rotate ([0,90,0]) cylinder (h = 4, r=0.9, center = true, $fn=100); } Background modifier example Debug Modifier Use this subtree as usual in the rendering process but also draw it unmodified in transparent pink. Usage example: # { ... } Example: difference() { // start objects cylinder (h = 4, r=1, center = true, $fn=100); // first object that will subtracted # rotate ([90,0,0]) cylinder (h = 4, r=0.3, center = true, $fn=100); // second object that will be subtracted # rotate ([0,90,0]) cylinder (h = 4, r=0.9, center = true, $fn=100); } OpenScad Debug Modifier example Root Modifier Ignore the rest of the design and use this subtree as design root. Usage example: ! { ... } Disable Modifier Simply ignore this entire subtree. Usage example: * { ... } Modules Defining your own module (roughly comparable to a macro or a function in other languages) is a powerful way to reuse procedures. module hole(distance, rot, size) { rotate(a = rot, v = [1, 0, 0]) { translate([0, distance, 0]) { cylinder(r = size, h = 100, center = true); } } } In this example, passing in the parameters distance, rot, and size allow you to reuse this functionality multiple times, saving many lines of code and rendering your program much easier to read. You can instantiate the module by passing values (or formulas) for the parameters just like a C function call: hole(0, 90, 10); The child nodes of the module instantiation can be accessed using the child() statement within the module: module lineup(num, space) { for (i = [0 : num-1]) translate([ space*i, 0, 0 ]) child(0); } lineup(5, 65) sphere(30); If you need to make your module iterate over all children you will need to make use of the $children variable, e.g.: module elongate() { for (i = [0 : $children-1]) scale([10 , 1, 1 ]) child(i); } elongate() { sphere(30); cube([10,10,10]); cylinder(r=10,h=50); } Include Statement The text in its current form is incomplete. For including code from external files in OpenSCAD, there are two commands available: include <filename> acts as if the contents of the included file were written in the including file, and use <filename> imports modules and functions, but does not execute any commands other than those definitions. A library file for generating rings might look like this (defining a function and providing an example): ring.scad: module ring(r1, r2, h) { difference() { cylinder(r = r1, h = h); translate([ 0, 0, -1 ]) cylinder(r = r2, h = h+2); } } ring(5, 4, 10); Including the library using include <ring.scad>; rotate([90, 0, 0]) ring(10, 1, 1); would result in the example ring being shown in addition to the rotated ring, but use <ring.scad>; rotate([90, 0, 0]) ring(10, 1, 1); only shows the rotated ring. Other Language Features The text in its current form is incomplete. Special variables All variables starting with a '$' are special variables. The semantic is similar to the special variables in lisp: they have dynamic instead of lexical scoping. $fa, $fs and $fn The $fa, $fs and $fn special variables control the number of facets used to generate an arc: $fa is the minimum angle for a fragment. Even a huge circle does not have more fragments than 360 divided by this number. The default value is 12 (i.e. 30 fragments for a full circle). The minimum allowed value is 0.01. Any attempt to set a lower value will cause a warning. $fs is the minimum size of a fragment. Because of this variable very small circles have a smaller number of fragments than specified using $fa. The default value is 2. The minimum allowed value is 0.01. Any attempt to set a lower value will cause a warning. $fn is usually 0. When this variable has a value greater than zero, the other two variables are ignored and full circle is rendered using this number of fragments. The default value is 0. When $fa and $fs are used to determine the number of fragments for a circle, then OpenSCAD will never use less than 5 fragments. This is the C code that calculates the number of fragments in a circle: int get_fragments_from_r(double r, double fn, double fs, double fa) { if (fn > 0.0) return (int)fn; return (int)ceil(fmax(fmin(360.0 / fa, r*2*M_PI / fs), 5)); } Spheres are first sliced into as many slices as the number of fragments being used to render a circle of the sphere's radius, and then every slice is rendered into as many fragments as are needed for the slice radius. You might have recognized already that the pole of a sphere is usually a pentagon. This is why. The number of fragments for a cylinder is determined using the greater of the two radii. The method is also used when rendering circles and arcs from DXF files. You can generate high resolution spheres by resetting the $fX values in the instantiating module: $fs = 0.01; sphere(2); or simply by passing the special variable as parameter: sphere(2, $fs = 0.01); You can even scale the special variable instead of resetting it: sphere(2, $fs = $fs * 0.01); $t The $t variable is used for animation. If you enable the animation frame with view->animate and give a value for "FPS" and "Steps", the "Time" field shows the current value of $t. With this information in mind, you can animate your design. The design is recompiled every 1/"FPS" seconds with $t incremented by 1/"Steps" for "Steps" times, ending at either $t=1 or $t=1-1/steps. If "Dump Pictures" is checked, then images will be created in the same directory as the .scad file, using the following $t values, and saved in the following files: $t=0/Steps filename="frame00001.png" $t=1/Steps filename="frame00002.png $t=2/Steps filename="frame00003.png" . . . $t=1-3/Steps filename="frame<Steps-2>.png" $t=1-2/Steps filename="frame<Steps-1>.png" $t=1-1/Steps filename="frame00000.png" Or, for other values of Steps, it follows this pattern: $t=0/Steps filename="frame00001.png" $t=1/Steps filename="frame00002.png $t=2/Steps filename="frame00003.png" . . . $t=1-3/Steps filename="frame<Steps-2>.png" $t=1-2/Steps filename="frame<Steps-1>.png" $t=1-1/Steps filename="frame<Steps-0>.png" $t=1-0/Steps filename="frame00000.png" Which pattern it chooses appears to be an unpredictable, but consistent, function of Steps. For example, when Steps=4, it follows the first pattern, and outputs a total of 4 files. When Steps=3, it follows the second pattern, and also outputs 4 files. It will always output either Steps or Steps+1 files, though it may not be predictable which. When finished, it will wrap around and recreate each of the files, looping through and recreating them forever. User-Defined Functions Define a function for code readability and re-use. Usage examples: my_d=20; function r_from_dia(my_d) = my_d / 2; echo("Diameter ", my_d, " is radius ", r_from_dia(my_d)); Echo Statements This function prints the contents to the compilation window. Useful for debugging code. Usage examples: my_h=50; my_r=100; echo("This is a cylinder with h=", my_h, " and r=", my_r); cylinder(h=my_h, r=my_r); Render Forces the generation of a mesh even in preview mode. Useful when the boolean operations become too slow to track. Needs description. Usage examples: render(convexity = 2) difference() { cube([20, 20, 150], center = true); translate([-10, -10, 0]) cylinder(h = 80, r = 10, center = true); translate([-10, -10, +40]) sphere(r = 10); translate([-10, -10, -40]) sphere(r = 10); } Surface Example 1: //surface.scad surface(file = "surface.dat", center = true, convexity = 5); %translate([0,0,5])cube([10,10,10], center =true); #surface.dat 10 9 8 7 6 5 5 5 5 5 9 8 7 6 6 4 3 2 1 0 8 7 6 6 4 3 2 1 0 0 7 6 6 4 3 2 1 0 0 0 6 6 4 3 2 1 1 0 0 0 6 6 3 2 1 1 1 0 0 0 6 6 2 1 1 1 1 0 0 0 6 6 1 0 0 0 0 0 0 0 3 1 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 Result: Example 2 // example010.dat generated using octave: // d = (sin(1:0.2:10)' * cos(1:0.2:10)) * 10; // save("example010.dat", "d"); intersection() { surface(file = "example010.dat", center = true, convexity = 5); rotate(45, [0, 0, 1]) surface(file = "example010.dat", center = true, convexity = 5); }