Scripting guide

Overview

In kokopelli, solid models are defined by Python scripts. A basic script has three main stages

• Import standard libraries
• Use functions from standard libraries to make shapes
• Assign shapes to output variables

Here is an example script with the three stages annotated

# Import the standard 2D shapes library
from koko.lib.shapes2d import *

# Use those functions to construct an output shape
c = circle(0, 0, 1)
for i in range(8):
    c -= rotate(circle(0, 1, 0.2), i*360/8)

# Assign output variables
cad.shape = c

This script produces a pseudo-gear shape

Standard Libraries

There are three standard libraries, which can be examined in the Libraries menu.

Library	Description
koko.lib.shapes2d	Flat shapes and transforms
koko.lib.shapes3d	Solid shapes and transforms
koko.lib.text	Sans-serif proportional font

In general, these libraries contain two types of functions.

• Constructor functions take in a set of values (position, size, etc.) and return a shape (circle, triangle, cube, pyramid, etc.).
• Transform functions take in a shape and a set of parameters, and return a modified shape. Transforms include move, scale, rotate, taper, shear, etc.

The objects returned by these operations have overloaded arithmetic operators, so addition and subtraction performs computation solid geometry.

The cad structure

The global variable cad defines what objects should be rendered, along with a few render settings.

Data attribute	Description	Valid values	Default
shape	Single shape to render	MathTree	None
shapes	Set of shapes to render	List or tuple of MathTree	Empty list
border	Size of empty border around model	Percentage (greater than 0)	0.05
render_mode	Force 2D or 3D render mode	'2D' or '3D' (string)	None
mm_per_unit	Real-world scale	Any value > 0	25.4 (setting for inch units)

For example, to define a circle of radius 1", we could write the following

from koko.lib.shapes import circle

cad.function = circle(0, 0, 1)
cad.mm_per_unit = 25.4