Parametric Design with OpenSCAD

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Claud Crawford
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2 OpenSCAD OpenSourceparametricdesigntool ExecutablesforWindows,Mac,Linux Freetodistribute,freetouse,cross platform Convertstextualinstructionsinto3Dshapes SupportsConstructiveSolidGeometry(CSG) modeling

3 ResourceLinks Downloads: UserManual:

5 Comments C/Java/C++commentingconventions Anytextafteradoubleforward slash(//)onaline isignoredbytheparser. Multi linecommentsarestartedwithaslash star (/*)andendedwithastar slash(*/)

6 NamedValues a.k.a.variables Anameisassignedavaluewiththeassignment operator(=).canuseexpressionsontheright handsideoftheassignmentoperatortocalculate values. CAUTION!:NamedValuesaresetatcompile time,notruntime!lastassignmenttakes precidence!(butseethe assign statement...)

handsideoftheassignmentoperatortocalculate values. CAUTION!

7 Example:

8 VariableAdvice Tokeepyourselfsane: Alwaysmakenewvariables,neverre assignnew valuestooldvariables. Thinkofvariablesas constants or descriptive names insteadof variables.

9 Vectors Example:dims=[w,d,h]; Usingsquarebrackets,declareavectorofvalues, eitherfromconstants,expressions,ornamed values/variables. Example:dims=[w*2,d+3,17];

10 Statements REQUIREsemicolonstoend! Ifyouforgetthesemicolontheparserwilltypically displaytheerrorasoccuringatthebeginningof thenextline. Socheckthelinebeforetheerror!

11 Sphere

12 Transformations Objectsandentiresub treescanhave transformationsappliedtothemthataffecttheir size,placement,colorandshape. Mostcommonlyused:rotate,translate Alsouseful:mirror,scale,color,hull Advanced:multmatrix,minkowski

13 Sphere Translated

14 sub tree Thetranslatecommandworksonasub treethat containschildnodes.bydefault,thesub tree includestheimmediatelyfollowingobject,ended byasemicolon. Ifyouuse{curlybrackets}todeliniatesub trees, youcanincludemorethanonemoduleorchild node.

15 Sphere&CubeTranslated

16 Sphere NotTranslated Note the extra semicolon!

17 CenteringonOrigin Bydefault,whenasphereiscreateditiscentered ontheorigin. However,acubeiscreatedwithitscorneratthe originbydefault. Thisiswhythecubeinthepreviousslideisnot centered withinthesphereaftertheyareboth translatedthesameamount.

However,acubeiscreatedwithitscorneratthe originbydefault.

18 Sphere&CubeTranslated

19 Creatingacenteredcube

20 SpecialArcControlvariables $fn Normallysettozero(0)toallow$faand$fs totakeeffect.ifsettoanumber,allcirclesare madewithexactly$fnstraightlinefragments. $fa Minimumangleforafragment.Numberof fragments=360/$fa.defaultsto12(i.e.30 fragmentsforafullcircle) $fs Minimumfragmentsize.Defaultsto2.Very smallcircleswillhaveasmallernumberof fragmentsthan$faspecifies.

$fa Minimumangleforafragment.Numberof fragments=360/$fa.defaultsto12(i.e.30 fragmentsforafullcircle) $fs Minimumfragmentsize.

21 Justuse$fn $fnistheeasiesttouse Ifyouwantcircles, cylinders,andspherestobesmoother,increase $fn. Thelarger$fnis,thelongercalculationstakeand themorevertices/filesizeyourexportedmodels willhave. Cansetglobally,orpasstospecificshapes individually.

22 $fnexample

23 Modules Likefunctions,butcanaffectsub treesthatfollow them,socanbeusedtoimplementcomplex transformationsaswellasobjects. Allowyoutoreusecode. Canacceptparameters. Useacurly bracketstodeliniatethesub treeof codethatisthemodule. Havelocalvariablenames.

24 VariableScope root/globalscopeisdifferentfromwithinamodule, soyoucanre defineavariablewithinamodule withoutaffectingitsvalueoutsideofthemodule. Reminder:Becausevariablesaresetatcompile timeinsteadofruntime,youcannotre assigna variableinsideofanifsub tree.

25 HexNutModule

26 Justuse$fn

27 MakeSpheres

28 MakeSpheres

29 MakeSpheres

30 MakeSpheres

31 Iterationviaforloops for(variable=<vector>)<sub tree> variableis assignedtoeachiteminthevectorandthesub treeisexecuted. for(variable=<range>)<sub tree> Range=[<start>:<end>] Range=[<start>:<increment>:<end>] Note:Rangesyntaxusescolons,andtheresulting rangeincludesthestartandendpoints

32 for Range

33 for Vector

34 for(multiplevariables) rangeandvector

35 ifstatements Syntaxlooksabouthowyouwouldexpect. Conditionallyexecutedsub treebasedupon booleanexpressionwithoptionalelseclause. Comeinusefulifyouwanttohave twodifferentversionsoftheobject(differentbolt patterns,adapterplates,etc..) Differentstyles/shapesbaseduponuserparameters. debug vs regular mode.

36 if syntax if ( <boolean Expression > ) { <executes on true> } else { <executes on false> }

37 if example

38 if example

39 ConstructiveSolidGeometry(CSG) Consistsofmodelingcomplexpartsasunions, intersections,anddifferencesof(relatively) simplerparts. Thehullandminkowskitransformationsarealso usefulforcreatingcompoundobjects.

40 Makingahollowbox Makealargecubeforyouroutsidedimensions. Makeasmallercubeforyour inside dimensions. Translatethesmallercubeinsidethelargercube (andhaveitstickoutthetopbyaverysmall amountsuchas0.01) Ithasto pokeout ofthetopjustalittlebitsothat thetopfaceisdefinatelyopen!

41 TwoCubes

42 HollowBox

43 HalfSphere intersection

44 Morethanonewaytoskinacat

45 OrderMatersforDifference!

46 hull

47 Modifiercharacters Characters(#,!,%,*)prependedtoobjectstomodify howtheyareprocessed. Generallyusedtovisualizewhatishappening,try outalimitedsetofcodewithoutothercode interfearing,etc. Mostusefulisthe#orDebugModifier,thatdraws objectsintransparentpinkforvisualization purposes.

48 intersection DebugView

49 OtherModifierCharacters Theothermodifiercharactersactuallyaffecthow youroutputisgenerated. % backgroundmodifier drawsthesub tree/objectwithtransparentgray,butignoresit forallotherrenderingpurposes.! rootmodifier IgnoreeverythingELSEinyour file,andonlyrenderthissub tree! * disablemodifier Disable/ignorethissubtree.

50 ResourceLinks Downloads: UserManual: