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add position $align

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Adrian Mariano 2023-06-16 18:27:15 -04:00
parent 4a4f871ae8
commit dcfbdfdc71
2 changed files with 3596 additions and 3499 deletions
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@ -375,6 +375,31 @@ cube([50,50,20],center=true)
position(TOP+RIGHT) left(5) cube([4,50,10], anchor=RIGHT+BOT);
```
When you position a child at an edge or corner of a parent object, you very likely
need to change the anchor for the child in a matching way to align the child with the surface and edge
of the parent. You can automate this process by making use of the `$align` special variable, which
is set by `position()`. To align a child with a corner you can do:
```openscad-3D
include<BOSL2/std.scad>
cuboid([50,40,15])
position(RIGHT+FRONT+TOP)
color("lightblue")prismoid([10,5],[7,4],height=4, anchor=$align);
```
In this example, the `$align` variable replaces the explicit anchor of `RIGHT+FRONT+BOT` that
would be required for this case. The `position()` module can also accept a list of positions,
and it will place a copy of the child at each location. However, if you want to align multiple
children to the parent in different locations, each child needs a different anchor. This can
be achieved using the `$align` variable:
```openscad-3D
cuboid([50,40,15])
position([RIGHT+TOP,LEFT+TOP])
color("lightblue")prismoid([10,5],[7,4],height=4, anchor=$align);
```
Positioning objects works the same way in 2D.
@ -463,6 +488,28 @@ prismoid([50,50],[30,30],h=40)
anchor_arrow(40);
```
The potential confusion that spin creates for the proper anchoring of children
can be eliminated using the `$align` variable which takes into account the spin
that the `orient()` module applies.
```openscad-3D
cuboid([50,40,15])
position(RIGHT+TOP)
orient(RIGHT)
color("lightblue")prismoid([10,5],[7,4],height=4, anchor=$align);
```
In this case, the correct anchor is chosen to place the child on the right side
with the appropriate anchor taking the spin into account. You can use this method
for children placed on the top by using orient with a TOP direction, but nonzero spin.
```openscad-3D
cuboid([50,40,15])
position(RIGHT+TOP)
orient(TOP, spin=90)
color("lightblue")prismoid([10,5],[7,4],height=4, anchor=$align);
```
## Attachment overview