Spinning Cube & Sphere

Table of Contents?

Getting Started

So, you've downloaded PySoy, managed to install it? Ready to actually do something with it? How would you like to create a simple scene and put a cube and a sphere inside? This should be a good way to start using PySoy. You will learn how to create a window, scene, bodies, then how to add light and a camera so you can see the stuff in the window. And finally, you'll add forces to the bodies you've created and see some action...

Open a text editor and start a new file. In this tutorial, save it as pysoy_primer.py. Import the soy module and the sleep method from the built-in time module in Python. We will also make a Client. In this client, there is a Window. This is the window that will show up. You will see when it appears that the title you set will be the title of the window. We set the background to white. Also, we make a scene to put our objects in. This scene is the 3-d space in which we will put things in. The scene is a soy.scenes.Room, so we call it "room".

import soy
from time import sleep

room = soy.scenes.Room(3.0)

client = soy.Client()
client.window.background = soy.atoms.Color('white')
client.window.title = "PySoy Primer Part 1"

At the end of the file, add the following lines. This is so that everything in your script continues to exist. This should remain at the end of your file at all times.

if __name__ == '__main__' :
	while client.window :

Run the script using python3

python3 pysoy_primer.py

Creating our Cube

In PySoy, 3d shapes are known as Bodies. We will create an instance of a subclass of Bodies known as Box, placing it in the scene we created earlier. We will place the cube slightly to the left. So, position will be soy.atoms.Position((-1, 0, 0)). The parameters of Position represent x, y, and z axes respectively. We set the size to 2 unit of length, width, and thickness. We also tell PySoy that we want our cube to be using a Texture. A checkered cubemap. And, of course, we set the colors of the checkered cubemap. The parameters of the Cubemap are - pattern, color1, color2, scaleX, scaleY, and size (scaleX and scaleY define the scaling we want to do with the checkered pattern - 1 means 2x2 texture, 2 means 4x4, and so on; size - doesn't really matter what you set it to, it is there to make sure that cubemap makes all sides of the same size). We set a small radius - that gives our cube rounded edges.

gold = soy.atoms.Color('gold')
firebrick = soy.atoms.Color('firebrick')

cubemap = soy.textures.Cubemap("checkered",
                               [gold, firebrick], 1,1,1)
room['cube'] = soy.bodies.Box()
room['cube'].position = soy.atoms.Position((-1, 0, 0))
room['cube'].material = soy.materials.Textured()
room['cube'].material.colormap = cubemap
room['cube'].size = soy.atoms.Size((2, 2, 2))
room['cube'].radius = 0.1

Run pysoy_primer.py again. Don't worry if your cube does not show up in your window yet. We simply know it exists in the blackness that is your scene.

Light, Camera, Action!

To make our cube show up, we need light to see it, a camera to watch it, and a projector to project what the camera sees onto the window, and of course we must position them properly, to be able to see what is happening. We still have a pure white window and that's just not very interesting. So, add these lines just under the line with which you created the scene.

room['cam'] = soy.bodies.Camera(soy.atoms.Position((0, 0, 15)))
room['light'] = soy.bodies.Light(soy.atoms.Position((-2, 3, 5)))

Then add this under the line with which you give your window a title.


This last line attaches the "output" of the camera, which exists in the 3D scene, to the white window you have open. This way, what the camera "sees" is what will be drawn inside the window. Anything inside your scene now is rendered and outputted to the Window.

Run pysoy_primer.py again. You should be able to see your first PySoy cube.


You want more? Let's add a sphere! What we do is very similar to what we did with cube, but there are some differences. Here, instead of soy.bodies.Box, we use soy.bodies.Sphere. Also we set the "size" of the sphere by setting its radius. Also we add a new cubemap to use for our sphere. For it, we don't set any colors, we will use the default ones - when you specify 0 colors, PySoy automatically sets the checkered pattern to use black and white. If you set 1 color only, PySoy will use that color and black. We position our sphere on soy.atoms.Position((1, 0, 0)), opposite to the cube.

cubemap2 = soy.textures.Cubemap("checkered")

room['sphere'] = soy.bodies.Sphere()
room['sphere'].radius = 1.0
room['sphere'].position = soy.atoms.Position((1, 0, 0))
room['sphere'].material = soy.materials.Textured()
room['sphere'].material.colormap = cubemap2


python3 pysoy_primer.py

Now you've got a Sphere, too! However, our cube and sphere are kind of boring, not doing anything but "existing." Let's do something about it.

Cube Rotation

Rotation in PySoy is done with the addTorque method.. we just have to specify our rotation speeds for each direction (x, y, z)

#Rotate the cube 1 unit in the X axis, 1 unit in the Y axis and 1 unit in the Z axis
room['cube'].addTorque(1, 1, 1)

#Rotate the sphere 1 unit in the X axis, 1 unit in the Y axis and 1 unit in the Z axis
room['sphere'].addTorque(1,  1,  1)

Enjoy the slowly spinning cube and sphere. :) It will take a few seconds for you to realize the amazingness of their three dimensions. Set these torque values higher and watch your cube and sphere spin faster. :)

Add some force to make these old fellas move.

#Give force to the cube - 1 unit in the X axis, 0 units in the Y axis and 0 units in the Z axis
room['cube'].addForce(1, 0, 0)

#Give force to the sphere -  -1 unit in the X axis, 0 units in the Y axis and 0 units in the Z axis
room['sphere'].addForce(-1, 0, 0)

As you can notice, these values are really low; crank them up (and Torque values, too) to get some real action. :)

You can also see the source code in the examples directory (pysoy_primer1.py).


Learn how to use Blender to create your own PySoy objects in Part 2: Modeling a Cabin