Jj openscad skill

OpenSCAD Code Generation Skill

CRITICAL RULE: NO TOOLS

Do NOT use any external tools, linters, compilers, renderers, or validation checks when generating OpenSCAD code. This means:

• Do NOT run openscad CLI or any OpenSCAD binary
• Do NOT use linters, syntax checkers, or static analysis tools
• Do NOT attempt to render, preview, or export models
• Do NOT use make, cmake, or build systems for OpenSCAD files
• Do NOT run any scripts to validate or test generated code

Generate code purely from knowledge. Write syntactically correct, idiomatic OpenSCAD code directly. If the user asks to verify or test code, explain that tool-based verification is not available and provide reasoning about correctness from the language specification instead.

How to Write OpenSCAD Code

OpenSCAD is a declarative, functional 3D compiler — not an interactive modeller. Code describes geometry; the engine renders it. Key principles:

1. Parametric by default — use variables, not magic numbers
2. Modules for reuse — encapsulate geometry in named modules with parameters
3. CSG composition — build complex shapes from primitives via union, difference, intersection
4. 2D → 3D pipeline — define 2D profiles, extrude to 3D
5. Functional style — prefer list comprehensions and functions over imperative loops

Quick Reference

For detailed information on any topic, read the corresponding reference file:

Topic	File
Language syntax, variables, types, operators, control flow	references/language-reference.md
3D primitives, transformations, CSG, boolean operations	references/3d-modeling-guide.md
2D primitives, extrusion, text, projection, import/export	references/2d-subsystem.md
List comprehensions, modules, children, recursion, special vars	references/advanced-features.md
Parametric design patterns, reusable libraries, best practices	references/tips-and-patterns.md
Complete advanced examples and worked designs	references/examples.md

Core Syntax at a Glance

// Variables
width = 10;
height = 20;
name = "bracket";

// Conditional assignment
x = (width > 5) ? 10 : 20;

// Function literal
f = function(x) x * 2;

// Module definition
module my_box(w, h, d) {
    cube([w, h, d], center = true);
}

// Function definition
function add(a, b) = a + b;

// Include (imports code, executes top-level statements)
include <lib.scad>

// Use (imports modules/functions only, no top-level execution)
use <lib.scad>

3D Primitives

sphere(r = 10);              // or sphere(d = 20);
cube([10, 20, 30], center = true);
cube(10);                    // shorthand for cube([10,10,10])
cylinder(h = 20, r = 5, center = true);
cylinder(h = 20, r1 = 10, r2 = 5);  // truncated cone
polyhedron(points = [...], faces = [...]);

2D Primitives

circle(r = 10);              // or circle(d = 20);
square([10, 20], center = true);
polygon(points = [[0,0], [10,0], [5,10]]);
text("Hello", size = 10, font = "Liberation Sans");

Transformations

translate([x, y, z]) { ... }
rotate([x, y, z]) { ... }          // Euler angles
rotate(a = 45, v = [0, 0, 1]) { ... } // axis-angle
scale([x, y, z]) { ... }
mirror([1, 0, 0]) { ... }          // mirror across YZ plane
resize([x, y, z]) { ... }
color("red", alpha = 0.5) { ... }
color([1, 0, 0, 0.5]) { ... }      // RGBA 0-1
multmatrix(m) { ... }              // 4x4 transform matrix
offset(r = 2) { ... }              // 2D offset
offset(delta = 2, chamfer = true) { ... }
hull() { ... }                     // convex hull of children
minkowski() { ... }                // Minkowski sum

Boolean / CSG Operations

union() { ... }                    // default if not specified
difference() { body(); holes(); }
intersection() { ... }

Extrusion

linear_extrude(height = 10, center = true, twist = 90, slices = 50) {
    circle(r = 5);
}
rotate_extrude(angle = 270, $fn = 100) {
    translate([10, 0, 0]) circle(r = 2);
}

Control Flow

// For loop (in module context — creates geometry)
for (i = [0:10]) { translate([i*5, 0, 0]) cube(3); }
for (i = [0:2:10]) { ... }         // step of 2
for (i = [1, 3, 7, 9]) { ... }    // list
for (i = list, j = list2) { ... }  // nested

// If statement
if (condition) { ... }
if (condition) { ... } else { ... }

// Let statement
let (x = 5, y = 10) { ... }

// Intersection for
intersection_for(i = [0:5]) { ... }

List Comprehensions

// Generate
[for (i = [0:10]) i * 2]
[for (i = [0:10]) if (i % 2 == 0) i]

// Flatten
[for (a = list1) each a]

// Let
[for (i = [0:10]) let (x = i*2) x + 1]

// Nested
[for (i = [0:3]) for (j = [0:3]) [i, j]]

Special Variables

Variable	Purpose
$fa	Minimum angle (degrees) for circle resolution
$fs	Minimum size (mm) for circle resolution
$fn	Fixed number of segments for circles
$t	Animation step (0-1)
$vpr	Viewport rotation
$vpt	Viewport translation
$vpd	Viewport camera distance
$vpf	Viewport field of view
$preview	true in preview (F5), false in render (F6)
$children	Number of children in a module

Modifier Characters

Prefix	Name	Effect
*	Disable	Disable the object
!	Root	Show only this object (and its children)
#	Debug	Highlight/transparent debug view
%	Background	Show as transparent background

#cube(10);        // highlight for debugging
%sphere(5);       // show as transparent background
!cylinder(r=3);   // show only this subtree
*cube(10);        // disabled, not rendered

Mathematical Functions

abs, sign, sin, cos, tan, acos, asin, atan, atan2, floor, round, ceil, ln, log, pow, sqrt, exp, rands, min, max, norm, cross, len, concat, lookup, str, chr, ord, search

Type Test Functions

is_undef, is_bool, is_num, is_string, is_list, is_function

Other Functions

echo(...), render(convexity), children([idx]), assert(condition, message), version(), version_num(), parent_module(idx)

Constants

• undef — undefined value
• PI — mathematical constant π (~3.14159)

Import/Export

// Import 2D
import("file.dxf");
import("file.svg");

// Import 3D
import("file.stl", convexity = 10);
import("file.off");
import("file.amf");
import("file.3mf");

// Surface (heightmap)
surface(file = "data.dat", center = true);
surface(file = "image.png", center = true);

// Export is done via GUI or CLI: -o output.stl

Community Libraries

When the user needs specialized functionality, suggest these well-known libraries:

• BOSL2 — Comprehensive: attachments, threading, gears, beziers, math, shapes
• NopSCADlib — Hardware parts (screws, bearings, PCBs), BOM generation
• dotSCAD — Math-heavy: path generation, fractals, Voronoi, maze
• BOLTS — Standard parts database (ISO screws, bearings, profiles)
• Round Anything — Rounded corners and fillets on 2D/3D shapes
• threads.scad — Thread generation (metric, imperial, custom)
• YAPP — Parametric electronics enclosure generator
• STEMFIE — Construction set parts library
• Catch'n'Hole — Snap-fit and catch mechanism generator
• Pathbuilder — Path-based 2D shape builder
• SCON — JSON serialization for OpenSCAD
• Constructive — Constraint-like mechanical part composition
• StoneAgeLib — General-purpose 3D printing utilities (CC0)
• UB.scad — Full 3D printing workflow solution
• Functional OpenSCAD — Functional programming extensions
• Mark's Enclosure Helper — Parametric enclosure generator
• funcutils — Functional utility functions
• Tray — Organizational tray generator
• Altair's 2D Library — Extended 2D shapes
• Doll House — Architectural modeling
• Dimensions — Dimension annotation for models

Best Practices

1. Always use center = true on primitives when building centered assemblies
2. Use $fn, $fa, $fs to control circle resolution — set $fn for precision, use $fa/$fs for adaptive
3. Prefer use <lib.scad> over include when you only need modules/functions (avoids side effects)
4. Name parameters explicitly: cylinder(h = 10, r = 5) not cylinder(10, 5)
5. Use assert() for parameter validation in modules
6. Use $preview to switch between fast preview and full render geometry
7. Use modifier characters (#, %) for debugging without modifying code
8. Keep modules small and composable — one module = one logical part
9. Use list comprehensions instead of imperative for-loops for data transformation
10. Document with comments — OpenSCAD has no docstring convention

For detailed patterns, advanced examples, and complete worked designs, read the reference files listed in the Quick Reference table above.