openscad

What this skill does

# OpenSCAD Skill

Create, validate, and export OpenSCAD 3D models. Supports parameter customization, visual preview from multiple angles, and STL export for 3D printing platforms like MakerWorld.

## Prerequisites

OpenSCAD must be installed. Install via Homebrew:
```bash
brew install openscad
```

## Tools

This skill provides several tools in the `tools/` directory:

### Preview Generation
```bash
# Generate a single preview image
./tools/preview.sh model.scad output.png [--camera=x,y,z,tx,ty,tz,dist] [--size=800x600]

# Generate multi-angle preview (front, back, left, right, top, iso)
./tools/multi-preview.sh model.scad output_dir/
```

### STL Export
```bash
# Export to STL for 3D printing
./tools/export-stl.sh model.scad output.stl [-D 'param=value']
```

### Parameter Extraction
```bash
# Extract customizable parameters from an OpenSCAD file
./tools/extract-params.sh model.scad
```

### Validation
```bash
# Check for syntax errors and warnings
./tools/validate.sh model.scad
```

## Visual Validation (Required)

**Always validate your OpenSCAD models visually after creating or modifying them.**

After writing or editing any OpenSCAD file:

1. **Generate multi-angle previews** using `multi-preview.sh`
2. **View each generated image** using the `read` tool
3. **Check for issues** from multiple perspectives:
   - Front/back: Verify symmetry, features, and proportions
   - Left/right: Check depth and side profiles
   - Top: Ensure top features are correct
   - Isometric: Overall shape validation
4. **Iterate if needed**: If something looks wrong, fix the code and re-validate

This catches issues that syntax validation alone cannot detect:
- Inverted normals or inside-out geometry
- Misaligned features or incorrect boolean operations
- Proportions that don't match the intended design
- Missing or floating geometry
- Z-fighting or overlapping surfaces

**Never deliver an OpenSCAD model without visually confirming it looks correct from multiple angles.**

## Workflow

### 1. Creating an OpenSCAD Model

Write OpenSCAD code with customizable parameters at the top:

```openscad
// Customizable parameters
wall_thickness = 2;        // [1:0.5:5] Wall thickness in mm
width = 50;                // [20:100] Width in mm
height = 30;               // [10:80] Height in mm
rounded = true;            // Add rounded corners

// Model code below
module main_shape() {
    if (rounded) {
        minkowski() {
            cube([width - 4, width - 4, height - 2]);
            sphere(r = 2);
        }
    } else {
        cube([width, width, height]);
    }
}

difference() {
    main_shape();
    translate([wall_thickness, wall_thickness, wall_thickness])
        scale([1 - 2*wall_thickness/width, 1 - 2*wall_thickness/width, 1])
        main_shape();
}
```

Parameter comment format:
- `// [min:max]` - numeric range
- `// [min:step:max]` - numeric range with step
- `// [opt1, opt2, opt3]` - dropdown options
- `// Description text` - plain description

### 2. Validate the Model
```bash
./tools/validate.sh model.scad
```

### 3. Generate Previews

Generate preview images to visually validate the model:
```bash
./tools/multi-preview.sh model.scad ./previews/
```

This creates PNG images from multiple angles. Use the `read` tool to view them.

### 4. Export to STL
```bash
./tools/export-stl.sh model.scad output.stl
# With custom parameters:
./tools/export-stl.sh model.scad output.stl -D 'width=60' -D 'height=40'
```

## Camera Positions

Common camera angles for previews:
- **Isometric**: `--camera=0,0,0,45,0,45,200`
- **Front**: `--camera=0,0,0,90,0,0,200`
- **Top**: `--camera=0,0,0,0,0,0,200`
- **Right**: `--camera=0,0,0,90,0,90,200`

Format: `x,y,z,rotx,roty,rotz,distance`

## MakerWorld Publishing

For MakerWorld, you typically need:
1. STL file(s) exported via `export-stl.sh`
2. Preview images (at least one good isometric view)
3. A description of customizable parameters

Consider creating a `model.json` with metadata:
```json
{
  "name": "Model Name",
  "description": "Description for MakerWorld",
  "parameters": [...],
  "tags": ["functional", "container", "organizer"]
}
```

## Example: Full Workflow

```bash
# 1. Create the model (write .scad file)

# 2. Validate syntax
./tools/validate.sh box.scad

# 3. Generate multi-angle previews
./tools/multi-preview.sh box.scad ./previews/

# 4. IMPORTANT: View and validate ALL preview images
#    Use the read tool on each PNG file to visually inspect:
#    - previews/box_front.png
#    - previews/box_back.png
#    - previews/box_left.png
#    - previews/box_right.png
#    - previews/box_top.png
#    - previews/box_iso.png
#    Look for geometry issues, misalignments, or unexpected results.
#    If anything looks wrong, go back to step 1 and fix it!

# 5. Extract and review parameters
./tools/extract-params.sh box.scad

# 6. Export STL with default parameters
./tools/export-stl.sh box.scad box.stl

# 7. Export STL with custom parameters
./tools/export-stl.sh box.scad box_large.stl -D 'width=80' -D 'height=60'
```

**Remember**: Never skip the visual validation step. Many issues (wrong dimensions, boolean operation errors, inverted geometry) are only visible when you actually look at the rendered model.

## OpenSCAD Quick Reference

### Basic Shapes
```openscad
cube([x, y, z]);
sphere(r = radius);
cylinder(h = height, r = radius);
cylinder(h = height, r1 = bottom_r, r2 = top_r);  // cone
```

### Transformations
```openscad
translate([x, y, z]) object();
rotate([rx, ry, rz]) object();
scale([sx, sy, sz]) object();
mirror([x, y, z]) object();
```

### Boolean Operations
```openscad
union() { a(); b(); }        // combine
difference() { a(); b(); }   // subtract b from a
intersection() { a(); b(); } // overlap only
```

### Advanced
```openscad
linear_extrude(height) 2d_shape();
rotate_extrude() 2d_shape();
hull() { objects(); }        // convex hull
minkowski() { a(); b(); }    // minkowski sum (rounding)
```

### 2D Shapes
```openscad
circle(r = radius);
square([x, y]);
polygon(points = [[x1,y1], [x2,y2], ...]);
text("string", size = 10);
```