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121 lines
3.3 KiB
Markdown
121 lines
3.3 KiB
Markdown
# Fractal Tree Tutorial
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<!-- TOC -->
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### Start with a Tree Trunk
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Firstoff, include the BOSL2 library, then make a starting module that just has a tapered cylinder for the tree trunk.
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```openscad-3D
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7)
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cylinder(h=l, d1=l/5, d2=l/5*sc);
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tree();
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```
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### Attaching a Branch
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You can attach a branch to the top of the trunk by using `attach()` as a child of the trunk cylinder.
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```openscad-3D
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7)
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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yrot(30) cylinder(h=l*sc, d1=l/5*sc, d2=l/5*sc*sc);
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tree();
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```
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### Replicating the Branch
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Instead of attaching each branch individually, you can make multiple copies of one branch, that are rotated relative to each other.
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```openscad-3D
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7)
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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zrot_copies(n=2) // Replicate that branch
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yrot(30) cylinder(h=l*sc, d1=l/5*sc, d2=l/5*sc*sc);
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tree();
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```
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### Use Recursion
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Since branches look much like the main trunk, we can make the tree recursive. Don't forget the termination clause, or else it'll try to recurse forever!
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```openscad-Med
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7, depth=10)
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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if (depth>0) { // Important!
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zrot_copies(n=2)
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yrot(30) tree(depth=depth-1, l=l*sc, sc=sc);
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}
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tree();
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```
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### Make it Not Flat
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A flat planar tree isn't what we want, so lets bush it out a bit by rotating each level 90 degrees.
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```openscad-Med
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7, depth=10)
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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if (depth>0) {
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zrot(90) // Bush it out
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zrot_copies(n=2)
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yrot(30) tree(depth=depth-1, l=l*sc, sc=sc);
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}
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tree();
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```
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### Adding Leaves
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Let's add leaves. They look much like squashed versions of the standard teardrop() module, so lets use that.
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```openscad-Big
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7, depth=10)
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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if (depth>0) {
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zrot(90)
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zrot_copies(n=2)
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yrot(30) tree(depth=depth-1, l=l*sc, sc=sc);
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} else {
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yscale(0.67)
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teardrop(d=l*3, l=1, anchor=BOT, spin=90);
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}
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tree();
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```
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### Adding Color
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We can finish this off with some color. The `color()` module will force all it's children and
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their descendants to the new color, even if they were colored before. The `recolor()` module,
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however, will only color children and decendants that don't already have a color set by a more
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nested `recolor()`.
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```openscad-Big
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include <BOSL2/std.scad>
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module tree(l=1500, sc=0.7, depth=10)
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recolor("lightgray")
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cylinder(h=l, d1=l/5, d2=l/5*sc)
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attach(TOP)
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if (depth>0) {
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zrot(90)
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zrot_copies(n=2)
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yrot(30) tree(depth=depth-1, l=l*sc, sc=sc);
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} else {
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recolor("springgreen")
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yscale(0.67)
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teardrop(d=l*3, l=1, anchor=BOT, spin=90);
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}
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tree();
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```
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