BOSL2 Library

BOSL2 is an extensive OpenSCAD library designed to simplify complex modeling. Key features include:

• Attachments: Position components relative to others (e.g., placing an object on the TOP of another, aligned RIGHT) without manual coordinate tracking.
• Rounding and Filleting: Advanced modules like cuboid() for rounded cubes, offset_sweep() for rounded extrusions, and prism_connector() for filleted connections.
• Shorthands: Readable alternatives to standard OpenSCAD commands (e.g., up(z) instead of translate([0,0,z])).
• Complex Objects: Support for path_sweep(), skin(), Beziers, NURBS, and metaballs() for organic surfaces.
• Building Blocks: Extended primitives like prisms, tubes, and shapes with inner radius support for guaranteed hole sizes.
• Texturing: Ability to apply repeating patterns or images (embossing) to surfaces.
• Parts Library: Functional components like gears, threading (NPT, bottle caps, screws), clips, hinges, and dovetail joints.
• Geometric Operations: Operations on 2D paths (regions) and 3D VNFs (Vertices 'N' Faces).
• Programming Aids: Math utilities (linear algebra, root finding), geometric intersections, coordinate transformations, and string/list processing.

BOSL2 enhances OpenSCAD's square() and circle() by replacing the center= argument with a more flexible anchor= argument. The anchor= argument takes a vector that points towards the part of the shape you want to align to the origin.

To use standard directions, you can use vector constants. Note that while these are 3D vectors, they work for 2D anchoring (except UP/DOWN).

Standard Vector Constants:

• LEFT: [-1, 0, 0]
• RIGHT: [1, 0, 0]
• FRONT, FORWARD, or FWD: [0, -1, 0]
• BACK: [0, 1, 0]
• CENTER or CTR: [0, 0, 0]

You can combine vectors to target corners, such as anchor=FRONT+RIGHT.

To visualize available anchor points on a shape, use the show_anchors() module as a child of that shape.

include <BOSL2/std.scad>
// Align the back edge center to the origin
square([60,40], anchor=BACK);

// Align the front right corner to the origin
square([60,40], anchor=FRONT+RIGHT);

// Center the shape
square([60,40], anchor=CENTER);

// Visualize anchors
circle(d=50)
    show_anchors();

3D edge masks (like rounding_edge_mask()) can be attached using edge_mask(). Unlike 2D masks, 3D masks can vary the rounding radius along the length of the edge.

Key features:

• Variable Radius: rounding_edge_mask() supports r1 and r2 to vary radius along the edge.
• Parent Size: edge_mask() sets a special variable $parent_size which can be used to ensure the mask covers the full length of the parent object (e.g., l = $parent_size.x + 0.1).
• Corner Smoothing: Using only edge masks can leave corners unrounded. Use corner_mask() combined with rounding_corner_mask() or teardrop_corner_mask() to smooth the intersections of edges.
• Teardrop Masks: teardrop_edge_mask() and teardrop_corner_mask() can be used to limit overhang angles for better FDM printing.

include <BOSL2/std.scad>
diff()
 cuboid([60,80,40]) {
  edge_mask(TOP+FWD)
   rounding_edge_mask(r = 10, l = $parent_size.x + 0.1);
  edge_mask(TOP+RIGHT)
   rounding_edge_mask(r = 10, l = $parent_size.y + 0.1);
  edge_mask(RIGHT+FWD)
   rounding_edge_mask(r = 10, l = $parent_size.z + 0.1);
  corner_mask(TOP+RIGHT+FWD)
            rounding_corner_mask(r = 10);
 }

BOSL2 allows you to make an object a child of another object, meaning the child's position is calculated relative to its parent rather than using absolute coordinates. By default, a child's anchor point coincides with the center of the parent. This approach simplifies modeling by removing the need to track absolute positions and orientations, making models easier to maintain and more intuitive.

There are three primary modules for controlling relative positioning:

1. position(): Places the child's anchor point at a specific chosen anchor point on the parent.
2. align(): Places the child on a parent's face without changing its orientation, aligning it with specific edges or corners of that face.
3. attach(): Places the child on a face (similar to stacking blocks) by mating a designated face of the child with a chosen face on the parent. It also supports alignment to the edges and corners of the face.

BOSL2 allows you to attach child shapes to parent shapes at specific anchor points.

1. position(anchor): Positions the child at the specified anchor point of the parent. By default, children are centered on the parent.
2. orient(anchor): Rotates the child to match the orientation of the parent's anchor point (which usually points outward from the shape's center). It does not move the child.
3. attach(anchor, [child_anchor]): The simplest method. It combines position() and orient() into one module. You can optionally provide a second argument to specify which side of the child should be attached to the parent's anchor.

Example of attach() usage:

• attach(LEFT+BACK): Positions and orients the child at the back-left corner.
• attach(BACK, LEFT): Attaches the LEFT side of the child to the BACK anchor of the parent.

include <BOSL2/std.scad>
// Using attach to position and orient a child at the parent's LEFT+BACK corner
square(50, center=true)
    attach(LEFT+BACK)
        #square([10,40], anchor=FWD);

// Using attach with a specific child side
square([10,50], center=true)
    attach(BACK, LEFT)
        #square([10,40], center=true);

The align() module simplifies positioning children on the faces, edges, or corners of a parent object. Unlike position(), which requires you to manually specify the correct anchor on the child to make it flush with the parent, align() automatically determines and applies the correct child anchor.

Key behaviors:

• Automatic Anchoring: align() overrides any anchor parameter specified on the child.
• Orientation: align() does not change the orientation of the child object. If you need the child to face a certain direction, use orient or spin separately.
• Multiple Placements: You can pass a list of anchors to align() to create multiple copies of a child, each positioned flush at a different location (e.g., one on the left and one on the right).
• Inset: Use the inset parameter to position children near an edge without being perfectly flush.

include<BOSL2/std.scad>
cuboid([50,40,15])
    align(TOP,RIGHT+FRONT)
        color("lightblue")prismoid([10,5],[7,4],height=4);