Introduction to pi3d
pi3d written by Tim Skillman, Paddy Gaunt, Tom Ritchford Copyright (c) 2015
There's plenty of 3D code flying around at the moment for the Raspberry Pi, but much of it is rather complicated to understand and most of it can sit under the bonnet!
pi3d is a Python module that aims to greatly simplify writing 3D in Python whilst giving access to the power of the Raspberry Pi GPU. It enables both 3D and 2D rendering and aims to provide a host of exciting commands to load in textured/animated models, create fractal landscapes, shaders and much more.
The pi3d module runs on platforms other than the Raspberry Pi (X on linux and Android using python-for-android) and runs with python 3 as well as 2. The OpenGLES2.0 functionality of the Raspberry Pi or Android is used directly or via mesa on 'big' machines. This makes it generally faster and opens up the world of shaders that allow effects such as normal and reflection maps, blurring and many others. It has various demos of built-in shapes, landscapes, model loading, walk-about camera and much more! See the demos included with this code and experiment with them ..
If you are reading this document as the ReadMe in the repository then you can find the full version of the documentation here http://pi3d.github.com/html/index.html
N.B. Shaders are now integrated into programs differently. The syntax used to be:
myshader = pi3d.Shader('shaders/uv_flat')
and is now:
myshader = pi3d.Shader('uv_flat')
this will use the default shaders 'bundled' with the package. The old format will be interpreted as 'look in a subdirectory of the directory where the demo is being run from.' This is probably what you would do if you rolled your own special shaders for your own project.
Demos on github.com/pi3d/pi3d_demos include
ForestWalk.py Walk about a forest on a landscape generated from a bitmap
Triceratops.py Large model loading with several bitmaps
BuckfastAbbey.py Explore a model of the beautiful Buckfast Abbey in Buckfastleigh, Devon, England
Earth.py Demonstrates semi-transparent clouds and hierarchical rotations
Clouds3D.py Blended sprites in perspective view
Raspberry_Rain.py Raining Raspberries, full-screen, over the desktop
RobotWalkabout.py Another off-planet example of a basic avatar robot drifting about
EnvironmentCube.py New environment cubes to try out in texture/ecubes - some high quality ones!
Shapes.py Demos available shapes and text in a 3D context
MarsStation.py Navigate around an abandoned Mars base-station with open/shut doors. Implements a new Level-Of-Detail (LOD) feature and TKwindow interface
Amazing.py Can you find yourself around the amazing maze?
TigerTank.py Ever played World Of Tanks (WOT)? This tank emulates how a WOT tank works. Uses realistic modelling in a TKwindow
Pong.py A snazzy 3D version of landscape pinball and pong against a Raspberry!
Blur.py Simulates giving the camera a focal distance and blurs nearer and further objects
LoadModelObj.py Loads a model from obj file (quicker) and applies a normal map and relfection map
Silo.py Uses the Building class to create a claustrophobic maze set in the desert.
Water.py A series of wave normal maps are used to animate a surface and produce a realistic moving reflection.
ClashWalk.py The graphics processor calculates where the camera can or cannot go depending on what is drawn in front of it. Potentially useful for first person navigation
CollisionBalls.py More bouncing balls across the screen - this time bouncing off each other on the desktop
Files and folders in this repository
Total zipped download from github c. 24 MB
- pi3d The main pi3d module files 540 kB
- shaders Shader files used by the pi3d module 33 kB
- echomesh Utility functions 14kB
- textures Various textures to play with 13 MB
- models Demo obj and egg models 26 MB
- fonts ttf and Bitmap fonts that can be using for drawing text see in /usr/share/fonts/truetype for others, or look online. 1.0 MB
- demos Source code of the demos included 96 kB
- screenshots Example screenshots of the demos included 860 kB
- pyxlib Library to enable use on general linux machines 209 kB
- ChangeLog.txt Latest changes of pi3d
- ReadMe.rst This file
Setup on the Raspberry Pi
Qick Start Guide, NB take the time to read the paragraphs below too
Here's a list of commands that have definitely worked on a couple of fresh rasbpian installs. Please take time to check out the paragraphs below even if you use this quick start recipe... certainly if you want to use python3 or have any non-standard aspirations or set-up. The long list of dependencies (3rd apt-get line) may take a while to run as well as the install Pillow. Both will create hundreds of lines of messages:
$ cd ~ $ sudo apt-get update $ sudo apt-get upgrade $ sudo apt-get install python-dev python-setuptools libjpeg-dev zlib1g-dev libpng12-dev libfreetype6-dev $ sudo apt-get install python-pip $ sudo pip install pi3d $ sudo pip install Pillow $ sudo raspi-config # set gpu_mem=128 $ git clone git://github.com/pi3d/pi3d_demos $ cd ~/pi3d_demos $ python Earth.py
Download, Extract and install
There are various possibilities depending on the machine, what's already installed and whether you want to work with some of the latest additions.
If you have pip installed you should be able to open a terminal and type:
$ sudo pip install pi3d or for python3 $ sudo pip-3.2 install pi3d
(or pip3 or whatever see below*) If you don't have pip installed you probably should install it as described below under Python Imaging as it's the easiest way to install Pillow at the moment. You can do the equivalent of pip install by downloading from https://pypi.python.org/pypi/pi3d and extracting the package, then in a terminal:
$ sudo python setup.py install or for python3 $ sudo python3 setup.py install
This will put the package into the relevant location on your device (for instance /usr/local/lib/python2.7/dist-packages/) allowing it to be imported by your applications.
If you might want to use features being added in the develop branch (i.e. between issues) you will need to download or clone the latest code from https://github.com/tipam/pi3d/ where there is a Download ZIP link, or you can install git (bundled in raspbian) then clone using git clone https://github.com/tipam/pi3d.git this git method will give you the option to update the code by running, from the pi3d directory git pull origin master
Memory Split setup
Although most demos work on 64MB of memory, you are strongly advised to have a 128MB of graphics memory split, especially for full-screen 3D graphics. In the latest Raspbian build you need to either run sudo raspi-config or edit the config.txt file (in the boot directory) and set the variable gpu_mem=128 for 128MB of graphics memory.
Install Python Imaging
Before trying any of the demos or pi3d, you need the Python Imaging Library as this is needed for importing any graphics used by pi3d (though see the minimal example below, which doesn't!). The original Imaging library is no longer really maintained and doesn't run on python_3. The better equivalent replacement is Pillow. In the near future Pillow will be the default imaging library but at the time of writing you need to:
$ sudo apt-get install python-dev python-setuptools libjpeg-dev zlib1g-dev libpng12-dev libfreetype6-dev $ sudo apt-get install python-pip $ sudo pip install Pillow ...
If you miss any of the dependent libraries and need to add them later you will have to pip uninstall then re pip install
For python3 support the first above will provide the required graphics libraries used by Pillow but you will need to swap to python3-dev and python3-setuptools also pip is different:
$ sudo apt-get install python3-pip $ sudo pip-3.2 install Pillow
(*on ubuntu pip3 could be other names, google for help or search:
$ sudo find / -name pip*
!) If you do not intend to run python3 you can install the old PIL: in the terminal type:
$ sudo apt-get install python-imaging
If you later switch to Pillow you will need to sudo remove python-imaging first
To run on Arch linux you will need to install:
$ pacman -S python2 $ pacman -S python2-pillow $ pacman -S python2-numpy
this worked for me. You could install python2-imaging rather than pillow but that's probably a retrograde step. The Arch repository doesn't seem to have python3-pillow or python3-pip etc. See FAQ for a description of all the steps to get a quick loading stand-alone pi3d SD card.
Setup on alternative Linux platforms
The machine will need to have a gpu that runs OpenGL2+ and obviously it will need to have python installed. If the Linux is running in vmware you will need to 'enable 3d acceleration'. You need to install libraries that emulate OpenGLES behaviour for the gpu:
$ sudo apt-get install mesa-utils-extra
This should install libEGL.so.1 and libGLESv2.so.2 if these change (which I suppose they could in time) then the references will need to be altered in pi3d/constants/__init__.py
The installation of PIL or Pillow should be the same as above but you are more likely to need to manually install python-numpy or python3-numpy
Editing scripts and running
Install Geany to run pi3d
Although you can use any editor and run the scripts in a terminal using python, Geany is by far the easiest and most compatible application to use for creating and running Python scripts. Download and install it with:
$ sudo apt-get install geany xterm
NB IDLE can't cope with some aspects of the way that most of the pi3d demos get key presses using the curses module. There will be an error to the effect curses.cbreak() returned ERR
Optionally, install tk.
Some of the demos require the tk graphics toolkit. To download and install it:
$ sudo apt-get install tk
Load and run
NB to get all the demos from github and run, in a terminal:
$ git clone https://github.com/pi3d/pi3d_demos.git $ cd ~/pi3d_demos $ python3 Minimal.py
or load any of the demos into Geany and run (using the cogs icon). As a minimum, scripts need these elements in order to use the pi3d library:
import pi3d DISPLAY = pi3d.Display.create() ball = pi3d.Sphere(z=5.0) while DISPLAY.loop_running(): ball.draw()
(Which should work even without python imaging) But.. a real application will need other code to actually do something, for instance to get user input in order to stop the program!
A Very Brief Explanation
The whole idea of pi3d is that you don't have to get involved in too many of the nuts and bolts of how the OpenGL graphics processor works however it might help to get an overview of the layout of pi3d. More detailed explanations can be found in the documentation of each of the modules. Read FAQ before you try anything ambitious or if anything goes wrong, obviously. There is a 3D Graphics Explanation where I try to explain in some more detail what is going on.
Display The Display class is the core and is used to hold screen dimension information, to initiate the graphics functionality and for 'central' information, such as timing, for the animation. There needs to be an instance of Display in existence before some of the other objects are created so it's a good idea to create one first job.
Shape All objects to be drawn by pi3d inherit from the Shape class which holds details of position, rotation, scale as well as specific data needed for drawing the shape. Each Shape contains an array of Buffer objects; normally only containing one but there could be more in complicated models created with external 3D applications.
Buffer The Buffer objects contain the arrays of values representing vertices, normals, faces and texture coordinates in a form that can be quickly read by the graphics processor. Each Buffer object within a Shape can be textured using a different image or shade (RGB) value and, if needed, a different Shader
Shader The Shader class is used to compile very fast programs that are run on the graphics processor. They have two parts: Vertex Shaders that do calculation for each of the vertices of the Buffer and Fragment Shaders applied to each pixel. In pi3d we have kept the shaders out of the main python files and divided them using the two extensions .vs and .fs The shader language is C like, very clever indeed, but rather hard to fathom out.
Camera In order to draw a Shape on the Display the Shader needs to be passed the vertex information in the Buffers and needs know how the Shape has been moved. But it also needs to know how the Camera has moved. The Camera class generally has just one instance and if you do not create one explicitly then Display will generate a default one when you first try to draw something. The Camera has position and rotation information similar to Shapes but also information to create the view, such as how wide-angle or telephoto the lens is.
Texture The Texture objects are used to load images from file into a form that can be passed to the Shader to draw onto a surface. They can also be applied as normal maps to give much finer local detail or as reflection maps - a much faster way to make surfaces look shiny than ray tracing.
Light To produce a 3D appearance most of the Shaders use directional lighting and if you draw a Shape without creating a Light a default instance will be created by the Display. The Light has properties defining the direction, the colour (and strength i.e. RGB values) and ambient colour (and strength).
Although drawing a Shape requires references to Shader, Light and Camera objects, default instances will be created automatically if they are not specified (as in the example minimal code above)
When you look through the demos you will see one or two things that may not be immediately obvious. All the demos start with:#!/usr/bin/python from __future__ import absolute_import, division, print_function, unicode_literals
Although these lines can often be left out, the first tells any process running the file as a script that it's python and the second is basically to help the transition of this code to run using python 3:import demo
Allows the demo files to be put in a different location from pi3d but still run. If you install pi3d using pip or python setup.py install then you can take this out:import pi3d
Is an alternative to importing just what you need i.e.:from pi3d.constants import * from pi3d import Display from pi3d.Texture import Texture from pi3d.Keyboard import Keyboard from pi3d.Light import Light from pi3d.Shader import Shader from pi3d.util.String import String ... from pi3d.shape.Sphere import Sphere from pi3d.shape.Sprite import Sprite
If you import the whole lot using import pi3d then you need to prefix classes and functions with pi3d. A third way to import the modules would be to use from pi3d import * this saves having to use the pi3d. prefix but is much harder to debug if there is a name conflict.
Please note that pi3d functions may change significantly during its development.
Bug reports, comments, feature requests and fixes are most welcome!
pi3d started with code based on Peter de Rivaz 'pyopengles' (https://github.com/peterderivaz/pyopengles) with some tweaking from Jon Macey's code (jonmacey.blogspot.co.uk/2012/06/).
Many Thanks, especially to Peter de Rivaz, Jon Macey, Richar Urwin, Peter Hess, David Wallin, Avishay Orpaz (avishorp), Guenter Kreidl, Benjamin Denozière and others who have contributed to pi3d - keep up the good work!
PLEASE READ LICENSING AND COPYRIGHT NOTICES ESPECIALLY IF USING FOR COMMERCIAL PURPOSES