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doc fixes

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This commit is contained in:
Adrian Mariano
2023-02-04 21:41:27 -05:00
parent 1b218145fd
commit 0511dbd967
3 changed files with 45 additions and 24 deletions
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distributors.scad
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@@ -22,10 +22,19 @@
// .
// Two gotchas may lead to models that don't behave as expected. While `if` statements work to control modules, you cannot
// use them to make variable assignments in your child object. If you write a statement like
// `if (condition) { c="red";}` then the `c` variable is set only in the scope of the `if` statement and is not available later on.
// Instead you must use the ternary operator. The second complication is
// that in OpenSCAD version 2021.01 and earlier, assignments in children were executed before their
// parent. This means that `$` variables like `$idx` are not available in assignments, so if you use them you will get a warning about an unknown variable.
// ```
// if (condition) { c="red";}
// else {c="green";}
// ```
// then the `c` variable is set only in the scope of the `if` and `else` clauses and is not available later on when you actually
// try to use it. Instead you must use the ternary operator and write:
// ```
/// c = condition ? "red" : "green";
// ```
// The second complication is
// that in OpenSCAD version 2021.01 and earlier, assignments in children were executed before their parent. This means
// that `$` variables like `$idx` are not available in assignments because the parent hasn't run to set them, so if you use them
// you will get a warning about an unknown variable.
// Two workarounds exist, neither of which are needed in newer versions of OpenSCAD. The workarounds solve the problem because
// **modules** execute after their parent, so the `$` variables **are** available in modules. You can put your assignments
// in a `let()` module, or you can wrap your child in a `union()`. Both methods appear below.
@@ -63,9 +72,9 @@
// xcopies(n=5,spacing=10)
// union()
// {
// shiftback = $idx%2==0 ? back(5) : IDENT;
// shiftback = $idx%2==0 ? back(10) : IDENT;
// spin = zrot(180*$idx/4);
// multmatrix(shiftback*spin) stroke([[-4,0],[4,0]],endcap2="arrow2",width=1/2);
// multmatrix(shiftback*spin) stroke([[-4,0],[4,0]],endcap2="arrow2",width=3/4, color="red");
// }
// Continues:
// ```