I've got some geometry that I'm wanting to slice into 8+ parts on various planes, and to add fixing holes to, and I'm wanting to make life easier than loads of nested difference() and intersection() operations. I'm using a "BinOps" module that takes an argument saying which binary to use, and then wanted to wrap this in another module that lets me specify multiple operations to apply to variable numbers of children. I first coded non-recursive with fixed depth (but null() module to let me still use it) and then struggled to code recursively as children() always seem to be unioned. Is there a better work around? module sphere1 () sphere (r=5); module slicer () translate ([-10,-10,-10]) cube ([10, 20, 20]); module sliceu () translate ([-10,-10,-10]) cube ([20, 20, 10]); module null(); // Applies operator to children(0) and children(1:last) // n=nop, d=difference, u=union, i=intersection module BinOp (Op) { if (Op == "n") children(0); else if (Op == "d") difference () {children(0); children([1:$children-1]);} else if (Op == "u") union () {children(0); children([1:$children-1]);} else if (Op == "i") intersection () {children(0); children([1:$children-1]);} } // Make this recursive! // Applies children(1) to children(0) first using first operator, and then works along module MultiOpOld (OpStr) { BinOp (OpStr[3]) { BinOp (OpStr[2]) { BinOp (OpStr[1]) { BinOp (OpStr[0]) { children(0); children(1); } children(2); } children(3); } children(4); } } // Apply all operations to children(0) with one operation per child after children(1) module MultiOp (OpStr, opnum = undef) { opnum = opnum==undef ? len(OpStr) : opnum; BinOp (OpStr[opnum-1]) { if (opnum==1) children(0); else MultiOp (OpStr, opnum=opnum-1) { // Would like to pass down all children except last one, but ... children(0); children(1); if ($children>3) children(2); if ($children>4) children(3); if ($children>5) children(4); } children(opnum); } } // Change the control string to slice in different ways. Will have 4-5 slice planes eventually. MultiOp ("ddnn") { sphere1(); slicer(); sliceu(); null(); null(); }

Nice strategy. However I am afraid there is no way to get it recursive because I guess the only way to pass down a subset of children is by explicitly enumerating it as you have done. Iterations either by for or by the form children(<index list>) returns the children union. For this reason, the intersection in BinOp may not give you what you intend. You might use intersection_for(). 2017-06-17 19:08 GMT-03:00 Ian Oliver <lists@foxhill.co.uk>: > I've got some geometry that I'm wanting to slice into 8+ parts on various > planes, and to add fixing holes to, and I'm wanting to make life easier > than loads of nested difference() and intersection() operations. > > I'm using a "BinOps" module that takes an argument saying which binary to > use, and then wanted to wrap this in another module that lets me specify > multiple operations to apply to variable numbers of children. > > I first coded non-recursive with fixed depth (but null() module to let me > still use it) and then struggled to code recursively as children() always > seem to be unioned. > > Is there a better work around? > > module sphere1 () sphere (r=5); > > module slicer () translate ([-10,-10,-10]) cube ([10, 20, 20]); > > module sliceu () translate ([-10,-10,-10]) cube ([20, 20, 10]); > > module null(); > > // Applies operator to children(0) and children(1:last) > // n=nop, d=difference, u=union, i=intersection > module BinOp (Op) { > if (Op == "n") children(0); > else if (Op == "d") difference () {children(0); > children([1:$children-1]);} > else if (Op == "u") union () {children(0); > children([1:$children-1]);} > else if (Op == "i") intersection () {children(0); > children([1:$children-1]);} > } > > // Make this recursive! > // Applies children(1) to children(0) first using first operator, and then > works along > module MultiOpOld (OpStr) { > BinOp (OpStr[3]) { > BinOp (OpStr[2]) { > BinOp (OpStr[1]) { > BinOp (OpStr[0]) { > children(0); > children(1); > } > children(2); > } > children(3); > } > children(4); > } > > } > > // Apply all operations to children(0) with one operation per child after > children(1) > module MultiOp (OpStr, opnum = undef) { > opnum = opnum==undef ? len(OpStr) : opnum; > BinOp (OpStr[opnum-1]) { > if (opnum==1) > children(0); > else > MultiOp (OpStr, opnum=opnum-1) { > // Would like to pass down all children except last > one, but ... > children(0); > children(1); > if ($children>3) children(2); > if ($children>4) children(3); > if ($children>5) children(4); > } > children(opnum); > } > } > > // Change the control string to slice in different ways. Will have 4-5 > slice planes eventually. > MultiOp ("ddnn") { > sphere1(); > slicer(); > sliceu(); > null(); > null(); > } > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

On 2017-06-17 16:55, Ronaldo Persiano wrote: > Iterations either by for or by the form children(<index list>) returns > the children union. Shame as this prevents them being "passed down" as separate children other than by using specific enumeration. This is OK as I just add as many "if .. children()" as I need and the extras don't cause issues other than looking messy. > For this reason, the intersection in BinOp may not give you what you > intend. You might use intersection_for(). I'm not sure what you mean. By this stage I don't mind the implicit union, and the ability of BinOp to take more than two children isn't actually used by MultiOp. I've set my OpStr to "iinn", "idnn", "dinn" and "ddnn" and all seem to work, and I can't see why using it for the extra "slices" won't work. I'm not sure whether to use the "union" capability of BinOp as I'll usually by using geometry than does this already.