Initial mutators tutorial.

tutorials/Mutators.md

@@ -0,0 +1,273 @@
+# Mutators Tutorial
+
+<!-- TOC -->
+
+## 3D Space Halving
+Sometimes you want to take a 3D shape like a sphere, and cut it in half.
+The BOSL2 library provides a number of ways to do this:
+
+```openscad
+    left_half() sphere(d=100);
+```
+
+```openscad
+    right_half() sphere(d=100);
+```
+
+```openscad
+    front_half() sphere(d=100);
+```
+
+```openscad
+    back_half() sphere(d=100);
+```
+
+```openscad
+    bottom_half() sphere(d=100);
+```
+
+```openscad
+    top_half() sphere(d=100);
+```
+
+You can use the `half_of()` module if you want to split space in a way not aligned with an axis:
+
+```openscad
+    half_of([-1,0,-1]) sphere(d=100);
+```
+
+The plane of dissection can be shifted along the axis of any of these operators:
+
+```openscad
+    left_half(x=20) sphere(d=100);
+```
+
+```openscad
+    back_half(y=-20) sphere(d=100);
+```
+
+```openscad
+    bottom_half(y=20) sphere(d=100);
+```
+
+```openscad
+    half_of([-1,0,-1], cp=[20,0,20]) sphere(d=100);
+```
+
+By default, these operators can be applied to objects that fit in a cube 1000 on a side. If you need
+to apply these halving operators to objects larger than this, you can give the size in the `s=`
+argument:
+
+```openscad
+    bottom_half(s=2000) sphere(d=1500);
+```
+
+## 2D Plane Halving
+To cut 2D shapes in half, you will need to add the `planar=true` argument:
+
+```openscad
+    left_half(planar=true) circle(d=100);
+```
+
+```openscad
+    right_half(planar=true) circle(d=100);
+```
+
+```openscad
+    front_half(planar=true) circle(d=100);
+```
+
+```openscad
+    back_half(planar=true) circle(d=100);
+```
+
+## Chained Mutators
+If you have a set of shapes that you want to do pair-wise hulling of, you can use `chain_hull()`:
+
+```openscad
+    chain_hull() {
+        cube(5, center=true);
+        translate([30, 0, 0]) sphere(d=15);
+        translate([60, 30, 0]) cylinder(d=10, h=20);
+        translate([60, 60, 0]) cube([10,1,20], center=false);
+    }
+```
+
+## Extrusion Mutators
+The OpenSCAD `linear_extrude()` module can take a 2D shape and extrude it vertically in a line:
+
+```openscad
+    linear_extrude(height=30) zrot(45) square(40,center=true);
+```
+
+The `rotate_extrude()` module can take a 2D shape and rotate it around the Z axis.
+
+```openscad
+    linear_extrude(height=30) left(30) zrot(45) square(40,center=true);
+```
+
+In a similar manner, the BOSL2 `cylindrical_extrude()` module can take a 2d shape and extrude it
+out radially from the center of a cylinder:
+
+```openscad
+    cylindrical_extrude(or=40, ir=35)
+        text(text="Hello World!", size=10, halign="center", valign="center");
+```
+
+
+## Offset Mutators
+
+### Minkowski Difference
+Openscad provides the `minkowski()` module to trace a shape over the entire surface of another shape:
+
+```openscad
+    minkowski() {
+        union() {
+            cube([100,33,33], center=true);
+            cube([33,100,33], center=true);
+            cube([33,33,100], center=true);
+        }
+        sphere(r=8);
+    }
+```
+
+However, it doesn't provide the inverse of this operation; to remove a shape from the entire surface
+of another object.  For this, the BOSL2 library provides the `minkowski_difference()` module:
+
+```openscad
+    minkowski_difference() {
+        union() {
+            cube([100,33,33], center=true);
+            cube([33,100,33], center=true);
+            cube([33,33,100], center=true);
+        }
+        sphere(r=8);
+    }
+```
+
+To perform a `minkowski_difference()` on 2D shapes, you need to supply the `planar=true` argument:
+
+```openscad-2D
+    minkowski_difference(planar=true) {
+        union() {
+            square([100,33], center=true);
+            square([33,100], center=true);
+        }
+        circle(r=8);
+    }
+```
+
+### Round2d
+The `round2d()` module lets you take a 2D shape and round inside and outside corners.  The inner concave corners are rounded to the radius `ir=`, while the outer convex corners are rounded to the radius `or=`:
+
+```openscad-2D
+    round2d(or=8) star(6, step=2, d=100);
+```
+
+```openscad-2D
+    round2d(ir=12) star(6, step=2, d=100);
+```
+
+```openscad-2D
+    round2d(or=8,ir=12) star(6, step=2, d=100);
+```
+
+You can use `r=` to effectively set both `ir=` and `or=` to the same value:
+
+```openscad-2D
+    round2d(r=8) star(6, step=2, d=100);
+```
+
+### Shell2d
+With the `shell2d()` module, you can take an arbitrary shape, and get the shell outline of it.
+With a positive thickness, the shell is offset outwards from the original shape:
+
+```openscad-2D
+    shell2d(thickness=5) star(5,step=2,d=100);
+    color("blue") stroke(star(5,step=2,d=100),closed=true);
+```
+
+With a negative thickness, the shell if inset from the original shape:
+
+```openscad-2D
+    shell2d(thickness=-5) star(5,step=2,d=100);
+    color("blue") stroke(star(5,step=2,d=100),closed=true);
+```
+
+You can give a pair of thickness values if you want it both inset and outset from the original shape:
+
+```openscad-2D
+    shell2d(thickness=[-5,5]) star(5,step=2,d=100);
+    color("blue") stroke(star(5,step=2,d=100),closed=true);
+```
+
+You can add rounding to the outside by passing a radius to the `or=` argument.
+
+```openscad-2D
+    shell2d(thickness=-5,or=5) star(5,step=2,d=100);
+```
+
+If you need to pass different radii for the convex and concave corners of the outside, you can pass them as `or=[CONVEX,CONCAVE]`:
+
+```openscad-2D
+    shell2d(thickness=-5,or=[5,10]) star(5,step=2,d=100);
+```
+
+A radius of 0 can be used to specify no rounding:
+
+```openscad-2D
+    shell2d(thickness=-5,or=[5,0]) star(5,step=2,d=100);
+```
+
+You can add rounding to the inside by passing a radius to the `ir=` argument.
+
+```openscad-2D
+    shell2d(thickness=-5,ir=5) star(5,step=2,d=100);
+```
+
+If you need to pass different radii for the convex and concave corners of the inside, you can pass them as `ir=[CONVEX,CONCAVE]`:
+
+```openscad-2D
+    shell2d(thickness=-5,ir=[8,3]) star(5,step=2,d=100);
+```
+
+You can use `or=` and `ir=` together to get nice combined rounding effects:
+
+```openscad-2D
+    shell2d(thickness=-5,or=[7,2],ir=[7,2]) star(5,step=2,d=100);
+```
+
+```openscad-2D
+    shell2d(thickness=-5,or=[5,0],ir=[5,0]) star(5,step=2,d=100);
+```
+
+
+### Round3d
+### Offset3d
+(To be Written)
+
+
+## Color Manipulators
+The built-in OpenSCAD `color()` module can let you set the RGB color of an object, but it's often
+easier to select colors using other color schemes.  You can use the HSL or Hue-Saturation-Lightness
+color scheme with the `HSL()` module:
+
+```openscad
+    for (h=[0:0.1:1], s=[0:0.1:1], l=[0:0.1:1]) {
+        translate(100*[h,s,l]) {
+            HSL(h*360,1-s,l) cube(10,center=true);
+        }
+    }
+```
+
+You can use the HSV or Hue-Saturation-Value color scheme with the `HSV()` module:
+
+```openscad
+    for (h=[0:0.1:1], s=[0:0.1:1], v=[0:0.1:1]) {
+        translate(100*[h,s,v]) {
+            HSV(h*360,1-s,v) cube(10,center=true);
+        }
+    }
+```
+
+

version.scad

@@ -8,7 +8,7 @@
 //////////////////////////////////////////////////////////////////////
 
 
-BOSL_VERSION = [2,0,492];
+BOSL_VERSION = [2,0,493];
 
 
 // Section: BOSL Library Version Functions