User Manual

Design a Model for Customizability

For a model to be customizable by AlaCAD, the customizable parameters need to be identifiable (this manual does not discuss parametric design as such). How to do this depends on your CAD program.

Customizable OpenSCAD Models

The OpenSCAD has a built in customizer, based on the Thingiverse customizer. Both of these use the same markup scheme, and AlaCAD supports a subset of these schemes:

• Package your model in a single .scad file.
• Place parameters at the top of the file, before the first curly brace you use.
• The general structure of a parameter declaration is:

   // variable description
   variable name = default value; // possible values

• Default values must be literals, no expressions are permitted.
• Parameters can be represented as:

A checkbox:

// Designated simply by assigning a boolean default value to a variable
shouldIStay = true;

A textbox:

// Designated by a string assignment, optionally specifying a max length
myNameIs = "Nobody"; // 7

A spinbox:

// Numeric assignment, optionally specifying a step size
imGettingOdd = 1; // 2

A slider:

// Numeric assignment, mandatory maximum value specification
crawling = 10; // [50]
// Minimum and maximum
king     = 20; // [10:50]
// Minimum, step size, and maximum
snake    = 30; // [10:5:50]

A drop down menu:

// Numeric with straight options
fontSize = 6;        // [5,6,8,9,10,12,14,18]
// String with straight options
direction = "north"; // [north, south, east, west]
// Numeric with labelled options
size      = 5;       // [5:S, 10:M, 20:L, 30:XL]
// String with labelled options
compass   = "SE";    // [N:North,NW:Northwest,W:West,SW:Southwest,S:South,SE:Southeast,E:East,NE:Northeast]

Customizable FreeCAD Models

In FreeCAD, there is (to my knowledge) no customization scheme defined yet, so AlaCAD uses a homegrown scheme:

• Add a spreadsheet named (in this priority) AlaCAD_Parameters or Parameters, or a link of that name to a spreadsheet (The first name is implemented to avoid name clashes with existing spreadsheets that may be formatted differently).
• For each parameter, add a line:
• An optional description goes in column A.
• The mandatory value goes in column B. It must have an alias name, giving the variable name.

A textbox

Non-numeric value in column C, optional maximum length in column D.

A spinbox:

Numeric value in column C, optional step size in column D.

A slider:

Numeric value in column C, minimum in column D, and either step size in column D and maximum in column E, or just the maximum in column D.

A drop down menu:

Value in column C and comma separated list of options (optionally followed by labels, as for OpenSCAD) in column D.

• The final object to be rendered must be named AlaCAD_Result or Result, or a link of that name to an object.

Customize a Model

Drag or select a FreeCAD or OpenSCAD file to the drop zone and then click the Customize Model button.

Adjust parameter settings to your liking and observe how they change the model. Once you have the model to your liking, click the Download Model button at the top right to download the STL for the model.

Colophon

AlaCAD is built on top of a sizable stack of technologies:

• STL output is rendered through Docker containers running FreeCAD and OpenSCAD
• The preview display is based on the Online3DViewer library.
• The web pages are styled with Metro UI
• The frontend is written using JavaScript, the backend using Swift.