OpenSCAD TutorialJohn Oliva - 2/22/17

Intro

What is OpenSCAD?

● 3D modeling program based on constructive solid geometry

● Dynamically typed language

● Open Source: https://github.com/openscad/openscad

● Windows, Mac OS X, Linux (14 - 23 MB), web app (openscad.net)

● GUI or CLI usage

Intro

Why OpenSCAD?

● Free to obtain and for commercial use

● Parametric - easy to adjust object to customize use

● Simple language

● Large amount of existing code freely available (Github, Thingiverse, etc.)

● Large user community

● Well established - been around since 2010

● Produces solid, watertight 3D objects

● Good online documentation

Intro

Differentiators from other 3D CAD?

● Declarative, procedure oriented programming

● Interactive design - but not by interacting directly with rendered model on screen

● Customizers○ Thingiverse○ Built into development version of OpenSCAD

● Computational generation of shapes (e.g. fractal shaped object)

Resources

● www.openscad.org

● cheatsheet: www.openscad.org/cheatsheet

● manual: en.wikibooks.org/wiki/OpenSCAD_User_Manual

● Libraries○ OpenSCAD general library of relativity

■ github.com/davidson16807/relativity.scad/wiki■ www.thingiverse.com/thing:349943

○ MCAD library■ github.com/openscad/MCAD■ Lots of resources for mechanical design

● Alternative language interfaces○ SolidPython: github.com/SolidCode/SolidPython○ OpenJSCAD: openjscad.org

● Web based OpenSCAD: openscad.net

Installation

● www.openscad.org/downloads.html

● Latest stable releases○ Mac OS X: 2015.03-3○ Windows: 2015.03-2○ Linux: 2015.03-2

● Much more recent development snapshots

Quick GUI Overview

● Preview/Render pane

● Code pane○ detachable○ supports external editor (Design->Automatic Reload and Preview)

● Console pane○ detachable

● Customizer pane○ detachable○ not currently available in stables releases

Workflow

● Iterate (until happy with design)○ Write OpenSCAD code○ Preview using F5 (generates CSG representation for OpenGL

rendering)

● Render to full geometry using F6 (generates CGAL representation, surfaces, edges, vertices)

● Export to a format for import into subsequent tool○ e.g. STL for import into siicer○ export formats: STL, OFF, AMF, DXF, SVG, CSG, PNG

Concepts - 2D Shapes

● Circle

● Square (actually rectangle)

● Polygon

● Text

Concepts - 3D Shapes

● Cube (actually rectangular prism)

● Sphere

● Cylinder (or cone)

Concepts - Transforms

● Translate

● Scale

● Rotate

● Mirror

● Color

● Others: resize, multmatrix, offset, hull, minkowski

Concepts - Boolean Operations

● Union

○ combines multiple shapes into a single object

● Difference

○ removes/subtracts second and remaining shapes from the first shape

● Intersection

○ leaves the parts that are common to all of the shapes included

Concepts - Extrusions

● Linear

○ extends a 2D object in the X/Y plane in the Z direction

● Rotational

○ rotates a 2D object defined in the X/Y plane around the Z axis

Concepts - Surface

● Creates a 3D object from:

○ height map data file

○ PNG image where grayscale indicates height

○ Can be used to create a lithophane

Examples

● Cup

● Customizer: Lego block

Language - Comments

● line: //

● block: /* */

Language - Console logging

● echo (aa,bb,cc,dd);

● echo (var=var);

Language - Types

● No declaration required

● Numbers (integer, floating point)

● Boolean (true/false)

● String

● Vector

● Undefined (undef)

Language - Variables

● variable_name = expression

● Variable values at calculated at compile-time, not run-time

● Special variables - start with $○ $fa minimum angle○ $fs minimum size○ $fn minimum # of fragments○ $t animation step○ Others: $vpr, $vpt, $vpd

Language - Operators

● arithmetic: *, /, +, -, %

● relational: <, >, <=, >=, ==, !=

● logical: &&, ||, !

● conditional: exp ? val1 : val2

● vector: +, -

Language - List Comprehensions

● Used to generate a list

● Examples

○ Squares: squares = [ for(i=[0:10]) i*i ]; echo (squares);

○ Divisible by 3: div3 = [ for(i=[0:20]) if (i%3 == 0) i ]; echo (div3);

Language - Modules

● Operates like a subroutine in other languages and does not return a value

● Most often used for constructing higher order 2D or 3D objects from simpler ones

● Format: module name (comma_sep_param_list) { … }

Language - Functions

● Operates like a function in other languages although defined as a single expression returning a value

● Most often used for constructing higher order 2D or 3D objects from simpler ones

● Format: function name (params) = expression yielding a value

● Example - Factorial

function factorial(n) = ( n==1 ? 1 : n * factorial(n-1) );fact=factorial(10);echo(fact=fact);

Language - Looping

● Often used to create multiple instances of objects parameterized by the loop variable

● Format

○ for (var = [start:end]) { actions }

○ for (var = [start:step:end]) { actions }

Language - Conditional

● if (logical expression) { actions } else { actions }

Language - Math Functions

● abs, sign, sin, cos, tan, acos, asin, atan, atan2, floor, round, ceil, ln, len, let, log, pow, sqrt, exp, rands, min, max

Language - Libraries

● include <filename>○ inserts contents of file at that point in the including file○ included file is OpenSCAD formatted○ modules and functions are defined○ commands are executed

● use <filename>○ modules and functions are defined○ included file is OpenSCAD formatted○ NO commands are executed

● import <STL/OFF/DXF file>○ imports and renders file