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Combining objects

Displaying multiple shapes

If you tried calling output a second time, you will have noticed that is overwrites the previous call. For example: 

from openscad import *
# Create a cube and a cylinder
cu = cube([5,5,5])
cy = cylinder(5)

# We display the cube
output(cu)
# We display the cylinder, which overwrites the previous output call
# THE CUBE IS NO LONGER DISPLAYED
output(cy)

So how do we display multiple shapes? Simple! We pass them all to the output function using a list: 

from openscad import *
# Create a cube and a cylinder
cu = cube([5,5,5])
cy = cylinder(5)

# Both objects are now displayed at once
output([cu,cy])

Combining objects with union()

Lets say you wanted to merge 2 objects into one, how could you do that? Well, you combine them with the union() method:

from openscad import *
# Create a cube and a cylinder
cu = cube([5,5,5])
cy = cylinder(5)

# Create a third object that is a fusion of the cube and the cylinder
fusion = cu.union(cy)
# alternatively you can also write:
fusion = union([cu, cy])

# Display the new object
output(fusion)

// Join the 2 objects into one
union() {    
    // Create a cube and a cylinder
    cube([5,5,5]);
    cylinder(5);
}

One important thing to note is the fact the union() does NOT edit the objects in place. Rather, it creates a third brand new object.
This means that:

  • You must assign the union to a variable, just calling cu.union(cy) alone will have no effects on cu or cy.
  • You keep access to the originals objects. For example, you could still display just the cube by using output(cu)

Substracting objects with difference()

You learned how to merge two objects into one, but what if you want to exclude an object from another? For that, you can use the difference() method:

from openscad import *
# Create a cube and a cylinder that overlap
cu = cube([5,5,5], center = True)
cy = cylinder(15, center = True)

# Substract the cylinder from the cube
diff = cu.difference(cy)

# Display the result
output(diff)

// Use difference() to substract the cylinder from the cube
difference() {
    // Create a cube and a cylinder that overlap
    cube([5,5,5], center = true);
    cylinder(15, center = true);
}

As you can see, this creates a cylinder-shaped hole in the cube!

Using operators

Using the union and difference method works great, but is a little heavy synthax-wise.
You can instead simplify it by using operators! Operators can also be used to easily translate or scale solid

Here is a table detailing which operator matches each method:

Operator Method
| union two solids
- difference two solids
& intersection of two solids
* scale an solid with a value or a vector
+ translate an solid with a vector

So, reusing our earlier examples, you could write 

from openscad import *
cu = cube([5,5,5])
cy = cylinder(5)

# Replaces cu.union(cy)
fusion = cu | cy

output(fusion)

There are some more conveniance function to translate or rotate objects.

from openscad import *
result = obj1.right(1).down(2) # directions are right, left, front, back, up, down
result2 = obj2.rotz(30) # 30 degrees, there is rotx, roty, rotz

Now that we know how to combine objects, lets see how we can position them.