Using ARRAY_BUFFER’s in PyOpenGL

Posted in How To, Programming, PyGLy with tags , , , , on 2013/02/16 by Adam Griffiths

I’m in the process of converting my code from Pyglet GL to PyOpenGL.
In doing so, my VBO objects stopped rendering.

It turns out the problem is glVertexAttribPointer.
The Pyglet GL version takes the last parameter (offset) as a number. I set this to 0 for arrays with no offset.

glVertexAttribPointer( in_position, 3, GL_FLOAT, GL_FALSE, 0, 0)

It seems that PyOpenGL expects the pointer value by absolute instead of relative.
The solution is to pass None instead of 0.

glVertexAttribPointer( in_position, 3, GL_FLOAT, GL_FALSE, 0, None)

If you have an actual offset to pass, you need to convert to a ctypes c_void_p (void*).
http://stackoverflow.com/questions/11132716/how-to-specify-buffer-offset-with-pyopengl

glVertexAttribPointer( in_position, 3, GL_FLOAT, GL_FALSE, 0, ctypes.c_void_p(offset))

Rotating a vector by a quaternion in GLSL

Posted in How To, Programming with tags , , , , on 2013/02/11 by Adam Griffiths

I’ve found numerous code samples which produce erroneous results in my shaders.

The functions I’ve found to work are the following:


vec4 multQuat(vec4 q1, vec4 q2)
{
return vec4(
q1.w * q2.x + q1.x * q2.w + q1.z * q2.y - q1.y * q2.z,
q1.w * q2.y + q1.y * q2.w + q1.x * q2.z - q1.z * q2.x,
q1.w * q2.z + q1.z * q2.w + q1.y * q2.x - q1.x * q2.y,
q1.w * q2.w - q1.x * q2.x - q1.y * q2.y - q1.z * q2.z
);
}

vec3 rotate_vector( vec4 quat, vec3 vec )
{
vec4 qv = multQuat( quat, vec4(vec, 0.0) );
return multQuat( qv, vec4(-quat.x, -quat.y, -quat.z, quat.w) ).xyz;
}

Source from here: http://www.opengl.org/discussion_boards/showthread.php/166386-Quaternions-and-hardware-skinning

And this version which is optimised:


vec3 rotate_vector( vec4 quat, vec3 vec )
{
return vec + 2.0 * cross( cross( vec, quat.xyz ) + quat.w * vec, quat.xyz );
}

Using gl_VertexID without any VBOs.

Posted in How To, Programming with tags , , , on 2013/02/03 by Adam Griffiths

Normally, gl_VertexID is the index of the currently rendered vertex element.

When you provide indices (GL_ELEMENT_ARRAY_BUFFER), gl_VertexID should match the value provided. Ie, the gl_VertexID value can repeat if you render the same element multiple times.

 

I say “should”, because this is NOT correct when you haven’t provided any VBO data.

This means, that if you are rendering using nothing but a shader and a GL_ELEMENT_ARRAY_BUFFER, the gl_VertexID will NOT match the indices you provide, and will instead be a sequence from 0 -> N.

The solution is to use a single VBO and use glDrawArrays.

 

Personally, I consider this a bug.

Adobe Air hanging when using SDK but not when packaged

Posted in How To with tags , , , , , on 2013/01/30 by Adam Griffiths

I just had an issue during the development of an Adobe AIR Application.
When using Flash Pro CS 6, the application hang in certain situations for 5 odd seconds.

I found a few peculiar quirks:

  • Packaged builds didn’t have the problem.
  • Moving the project to a different directory fixed the problem.
  • Clean checkouts of the source didn’t have the problem
  • Re-creating the project in Flash Pro CS 6 didn’t fix the problem.

The console was printing the following messages

Breakpoint not set; No executable code at line ###

It turns out the problem was old breakpoints that don’t exist anymore.
There’s not trivial way to remove all the breakpoints (the button was greyed out!).
The easiest way I found (on OS-X) was to do the following:

vi ~/Library/Application\ Support/Adobe/Flash\ CS6/en_US/Configuration/Debugger/AsBreakpoints.xml

Remove all the breakpoint entries in the XML.
The file should look similar to this:

<?xml version="1.0"?>
<flash_breakpoints version="1.0">
</flash_breakpoints>

This resolved the issue.

Compiling Python on Ubuntu / Linux

Posted in Twisted Pair with tags , , , , on 2012/09/25 by Adam Griffiths

I’ve been having problems installing Python on my Ubuntu machine because of errors with setup tools.

During installation you get the following error:

Installing distribute into /home/ting/.pythonbrew/pythons/Python-2.7.3
ERROR: Failed to install setuptools. See /home/ting/.pythonbrew/build.log to see why.
Skip installation of setuptools.

And if you try and use pip / easy_install, you get this:

ImportError: No module named setuptools

It turns out the answer is simple, we’re missing some libraries required to compile it.

sudo apt-get build-dep python2.7

BAM! Pythonbrew works!

PyGLy steps into the future

Posted in Development, PyGLy, Twisted Pair with tags , , , , , on 2012/09/21 by Adam Griffiths

I’ve been working quite heavily on PyGLy for the last few weeks and I’m incredibly pleased to announce that PyGLy is now OpenGL 3 clean!

It took more work than I hoped. Not because of PyGLy (it was already pretty good), but Pyglet’s OpenGL Core (3+) support on OS-X, is well… broken.
I had to integrate a patch written by someone else and patch out 2 of the window event handlers.
The main reason for this is that OpenGL Core on OS-X is limited to 3.2, and is Core only (no legacy compatibility).
These changes can be found in my Github repository.

Pyglet isn’t without it’s problems. It is quite heavy weight in places. There is no support for float or 1D textures.
Other problems are it’s usage of legacy calls. These are scattered throughout the code base and prevent me from using even the Label or VertexList classes.
I would LOVE to help with the development of Pyglet… but I find the code… very confusing.
It’s got a fair amount of abstraction. Tracing even a vertex buffer blows my mind.

Regardless, I hope these issues will be fixed soon.

OpenGL and GLSL support in OS-X

Posted in Twisted Pair with tags , , , , on 2012/08/13 by Adam Griffiths

I had difficulty finding the supported OpenGL and GLSL versions in OS-X.
Using Pyglet, I get errors trying to use versions GLSL 1.30 and above. Printing out the version returns 1.20.

from ctypes import *
from pyglet.gl import *

print "OpenGL version", gl_info.get_version()

plain = string_at(glGetString(GL_SHADING_LANGUAGE_VERSION)).split(' ')[0]
major, minor = map(int, plain.split('.'))
version = major*100 + minor
print "GLSL Version",version

Looking around I found this information.
Mac OS-X OpenGL Support

Legacy would infer the “Fixed Function Pipeline” and Core would be modern OpenGL.
So it seems that legacy OpenGL (normal Pyglet) is stuck with GLSL 1.20 and Core has 1.50.

This code can be found on the Pyglet source repository that enables OpenGL 3 (Core).
Enable OpenGL 3 in Pyglet

But the ouput I get is not correct.

OpenGL version 2.1 ATI-1.0.25
GLSL Version 120

According to this conversation, it appears that Pyglet ignores the OpenGL version on OS-X currently.

PyGLy Progress

Posted in Development, Twisted Pair with tags , , , on 2012/07/06 by Adam Griffiths

Work on PyGLy is progressing well. The code is better designed and cleaner than I’d hoped, so I’m very pleased.

I’m wanting to keep PyGLy thin, so not much more new functionality will be added. New features will go into higher level projects that sit on top.

I tried some NumPy optimisations with BLAS and other libs, but haven’t seen much improvement. Biggest change was running Python with ‘-O’, which got me another 10 FPS.

Dev continues!

Getting Cocos 1.x / Kobold2D to work with the latest CocosBuilder

Posted in Development, How To, Programming, Rant with tags , , , , , on 2012/03/30 by Adam Griffiths

CocosBuilder is a brilliant tool that helps you rapidly develop Cocos2D applications.

But the latest versions require the Cocos 2.x branch.

Some of us are stuck with Cocos 1.x for the time being. So let’s figure out how to get things going.

Continue reading

Adventures in Kivy

Posted in How To, Programming, Rant with tags , , , , , , on 2012/03/22 by Adam Griffiths

So here is a semi-live blog as I delve into Kivy.

Mission #1: Attempt to resize the default window

Ok let’s start at the start.

We first create an object that inherits from App. Done.

Ok, and the examples all return a widget from the App’s build() method. So we don’t over-ride __init__… ok… thats… unique.

Perhaps the widget is the window if it is returned from the build() method?

Widget is not the window. Widget returned from build() is added to the window. So… where is the window created?

Window docs state the window has a constructor that lets you set the window size. Ok, cool. But we don’t create the window… so.. we can’t use the constructor… sigh.

Ok, Window has a static accessor.

kivy.core.window.Window = None

No comment on what is stored here but I assume it’s the instantiated window. It doesn’t mention when it is set… handy!

Only 1 window allowed. Ok… weird. Well… let’s try that.

import kivy.core.window.Window
AttributeError: 'module' object has no attribute 'window'

Awesome…

Let’s scour the code.

Screen capture of Kivy window module

No Window.py file……… how far does this rabbit hole go.

Ok, let’s check out the __init__.py file in the window module.

class WindowBase(EventDispatcher):
 '''WindowBase is a abstract window widget, for any window implementation.

So… window base is in there. Feel free to scream now.

So we can get this by importing kivy.core.window and just leaving the class off the end.

import kivy.core.window
...
def build(self):
    print kivy.core.window.Window.size
    return None
(800, 600)

Ok sweet, thats our window.

So let’s change its size.

def build(self):
    print kivy.core.window.Window.size
    kivy.core.window.Window.size = (1024, 768)
    print kivy.core.window.Window.size
    return None
File "/Users/adamgriffiths/Workspace/VirtualEnvs/progress_quest/lib/python2.7/site-packages/kivy/core/window/__init__.py", line 243, in _set_size
 if super(WindowBase, self)._set_size(size):
 AttributeError: 'super' object has no attribute '_set_size'

FFFFFFFUUUUUUUUUUU

Ok, so after some googling we find this post about the relationship between the App and Window classes.

His solution is to pass the size as a command line parameter……….. LAME. That kinda throws the whole configuration settings thing out the window.

Looking through the Kivy code we find this block inside their base window class’ __init__ method.

if 'fullscreen' not in kwargs:
    fullscreen = Config.get('graphics', 'fullscreen')
        if fullscreen not in ('auto', 'fake'):
        fullscreen = fullscreen.lower() in ('true', '1', 'yes', 'yup')
    kwargs['fullscreen'] = fullscreen
if 'width' not in kwargs:
    kwargs['width'] = Config.getint('graphics', 'width')
if 'height' not in kwargs:
    kwargs['height'] = Config.getint('graphics', 'height')

Ok, so we can try and set it via the global config object.

So let’s add that to our App class.

def build_config(self, config):
    config.adddefaultsection('graphics')
    config.setdefault('graphics', 'width', 1024)
    config.setdefault('graphics', 'height', 768)
    config.set('graphics', 'height', 1024)
    config.set('graphics', 'width', 768)

Run the code and……

(800, 600)

……. sigh

So let’s put some debug INSIDE kivy and see what is happening. We’ll also force it to pull the ‘graphics’ setting and ignore kwargs.

if True: #'width' not in kwargs:
    kwargs['width'] = Config.getint('graphics', 'width')
print kwargs['width']
if True: #'height' not in kwargs:
    kwargs['height'] = Config.getint('graphics', 'height')
print kwargs['height']

And the output…

800
600

…. calm blue ocean…. calm blue ocean….

Ok… google…

Hmm.. ok, this post on the kivy-users forum (because documentation is for lusers) shows a similar method.

They use the Config module directly instead of the config object passed to App….. because….. they’re not the same? Well.. let’s try it anyway.

from kivy.config import Config
Config.set('graphics', 'width', 1024)
Config.set('graphics', 'height', 768)

And our output

(800, 600)

Ok, weird because the window HAS ACTUALLY CHANGED SIZE.

Whatever. We’re all living in crazy-ville atm so let’s just pretend everything is normal.

So let’s move that inside our build_config() method.

def build_config(self, config):
    Config.set('graphics', 'height', 1024)
    Config.set('graphics', 'width', 768)

And the output

[INFO ] Kivy v1.1.1
[INFO ] [Logger ] Record log in /Users/adamgriffiths/.kivy/logs/kivy_12-03-22_40.txt
[INFO ] [Factory ] 102 symbols loaded
[INFO ] [Text ] using <pygame> as text provider
[INFO ] [Loader ] using <pygame> as thread loader
[INFO ] [Window ] using <pygame> as window provider
[WARNING] [Window ] Unable to use <pygame> as windowprovider
[CRITICAL] [Window ] Unable to find any valuable Window provider at all!
Fatal Python error: (pygame parachute) Segmentation Fault
Abort trap: 6

(╯°□°)╯︵ ┻━┻

Install GCC with XCode 4.3

Posted in How To with tags , , , , on 2012/03/21 by Adam Griffiths

XCode 4.3 removed GCC from the default installation. To get it back simply do the following:

  1. Run XCode
  2. Select XCode -> Preferences -> Downloads -> Command Line Tools -> Install

Voila! GCC is now installed and libraries such as PIL will once again install.

Installing Kivy on OS-X from PIP and Homebrew

Posted in How To, Programming with tags , , , , , on 2012/03/19 by Adam Griffiths

Begin by following this guide to get your python environment setup.

If you aren’t using virtualenv, then feel free to ignore those commands (mkvirtalenv, cdvirtualenv).

Remember to run ‘brew’ commands as the current user and not root.

Install SDL

brew install sdl sdl_image sdl_mixer sdl_ttf smpeg portmidi

Install Mercurial to gain access to PyGame repository.

brew install mercurial

Create a virtual environment to work in

mkvirtualenv kivy
cdvirtualenv

Install our Kivy dependencies and then finally, Kivy itself.

pip install cython
pip install pil
pip install hg+http://bitbucket.org/pygame/pygame</pre>
pip install kivy

If you don’t install PIL or PyGame, you will get errors such as this

(kivy-test)Vibur:kivy-test adamgriffiths$ python src/main.py 
[INFO   ] Kivy v1.1.1
[INFO   ] [Logger      ] Record log in /Users/adamgriffiths/.kivy/logs/kivy_12-03-19_4.txt
[INFO   ] [Factory     ] 102 symbols loaded
[WARNING] [Image       ] Unable to use <pygame> as loader!
[WARNING] [Image       ] Unable to use <pil> as loader!
[WARNING] [Text        ] Unable to use <pygame> as textprovider
[WARNING] [Text        ] Associated module are missing
[WARNING] [Text        ] Unable to use <pil> as textprovider
[WARNING] [Text        ] Associated module are missing
[CRITICAL] [Text        ] Unable to find any valuable Text provider at all!
 Traceback (most recent call last):
   File "src/main.py", line 2, in <module>
     from kivy.uix.button import Button
   File "/Users/adamgriffiths/Workspace/VirtualEnvs/kivy-test/lib/python2.7/site-packages/kivy/uix/button.py", line 38, in <module>
     from kivy.uix.label import Label
   File "/Users/adamgriffiths/Workspace/VirtualEnvs/kivy-test/lib/python2.7/site-packages/kivy/uix/label.py", line 94, in <module>
     from kivy.core.text import Label as CoreLabel
   File "/Users/adamgriffiths/Workspace/VirtualEnvs/kivy-test/lib/python2.7/site-packages/kivy/core/text/__init__.py", line 520, in <module>
     Label.register('DroidSans',
 AttributeError: 'NoneType' object has no attribute 'register'

Installing Virtualenv and Pythonbrew on OS-X

Posted in How To, Programming with tags , , , on 2012/03/19 by Adam Griffiths

This post will help you get Pythonbrew and Virtualenv installed on OS-X. Two important libraries for Python development.

  • Pythonbrew lets you install multiple python installations without affecting your system’s Python install.
  • Virtualenv lets you set up isolated python installations and modules for each project.

Begin by installing Pythonbrew

# install pythonbrew locally
# do NOT install to your system python directory
curl -kL http://xrl.us/pythonbrewinstall | bash

Install your desired Python versions

# get a list of available python versions
python list -k

# install desired python
# force the install as python fails some tests at the moment
# https://twistedpairdevelopment.wordpress.com/2012/01/16/installing-python-with-pythonbrew-on-mac-os-x
pythonbrew install <VERSION>
pythonbrew use

# should print out
python --version

# virtualenvwrapper must be installed for each python version
pip install virtualenvwrapper

You can install virtualenv and virtualenvwrapper into the system Python, or into your newly installed python.

# install into system python
# do this if you plan to use the system python as default
sudo pip install virtualenv
sudo pip install virtualenvwrapper

You can install virtualenv and virtualenvwrapper into the system Python, or into your newly installed python.

# install into pythonbrew installed python
# do this if you want to over-ride the default python installation
pythonbrew switch <VERSION>
pip install virtualenv
pip install virtualenvwrapper

Add support for Pythonbrew to bash by adding the following to the end of your ~/.bashrc

Follow this guide if you want to make your .bashrc modular.

#-------------------------------------------------------------
# Python definitions
#-------------------------------------------------------------

# Pythonbrew
# add pythonbrew support
if [[ -s $HOME/.pythonbrew/etc/bashrc ]]; then
source $HOME/.pythonbrew/etc/bashrc
fi

Add virtualenvwrapper support to ~/.bashrc


#-------------------------------------------------------------
# Python definitions
#-------------------------------------------------------------

# Virtualenvwrapper
# virtualenv wrapper support
export WORKON_HOME=~/Workspace/VirtualEnvs

if [[ -s /usr/local/bin/virtualenvwrapper.sh ]]; then
source /usr/local/bin/virtualenvwrapper.sh
fi

# PIP
# tell pip to only install inside virtualenvs
export PIP_REQUIRE_VIRTUALENV=true

# make pip use the virtualenv dir
export PIP_VIRTUALENV_BASE=$WORKON_HOME

# add pip bash completion
# use eval to avoid the error "Could not find an activated virtualenv (required)."
eval `pip completion --bash`

Close the terminal and re-open it to reload your .bashrc.

When creating Virtualenv environments, virtualenv will use the currently set Python install.

If you wish to use a Python install other than the current system install, run the following command before running mkvirtualenv.


pythonbrew use <VERSION>

Note: I’ve found that virtualenvwrapper has stopped obeying this. To force virtualenvwrapper to install a specific version, do the following.

pythonbrew use <VERSION>
MY_PYTHON="$(command which python)"
mkvirtualenv -p $MY_PYTHON <NAME>

Some basic Virtualenvwrapper commands:

  • mkvirtualenv PROJECTNAME – create a new virtualenv project.
  • workon PROJECTNAME – enter the virtualenv for the project.
  • deactivate – stop working on the current virtualenv project.
  • cdvirtualenv – change to the directory of the current virtualenv project.

If you need to add environment variables to your project, edit the ‘bin/postactivate’ file inside the virtualenv directory. This file is executed when the ‘workon’ command is run and can be used to add more paths to $PYTHONHOME and other useful commands.

Initial release of PyGLy

Posted in Development, Programming, Twisted Pair with tags , , , , on 2012/03/07 by Adam Griffiths

It’s a pretty big day for us, as I’m pushing my labor of love, PyGLy, to GitHub.

PyGLy is a 3D framework developed in pure python.

I’ve been dismayed at the state of game frameworks on Python.

There are a large number of quality 3D engines and frameworks out there. However, there are serious problems with the ‘engines’ out there that have Python bindings.

  • Not truly cross-platform (this is Python FFS!).
  • Not free.
  • Not maintained.
  • No documentation (the worst culprit).
  • Bindings are 2nd class citizens and you still need to code C/C++/Whatever.
  • Don’t work with latest versions of code.

Most engines have bindings created by the community. The problem is these are quickly dumped when the person moves on.

Python only 3D engines seem… well… stagnant.

  • PySoya and PySoy seem to be seething at each other but not really producing much.
  • PyGame is just SDL in disguise.
  • The rest… well they all 404 now.

For the most part, 3D game development on Python is dead.

So, behind the scenes, I’ve been writing my own 3D framework for Python, PyGLy.

“Framework” is an important word there. PyGLy does not force any one methodology on you. PyGLy simply provides functionality to wrap common functionality. Windows, Viewports, Scene Graph Nodes, Cameras. It’s up to you to put them together how you want.

Obviously some things are going to be coupled together. But for the most part, PyGLy just gets out of the way.

At the moment PyGLy is quite small, but it is in active development and already has features that may interest some.

I think the best case for it at the moment is for people wanting to rapidly prototype in 3D but not be abstracted from the rendering process. PyGLy lets you forget about the scene graph and just concentrate on rendering your objects. Rendering is performed via callbacks. You can make any OpenGL call you want in these callbacks.

PyGLy is the foundation of our Python 3D work, so expect it to be actively developed going forward.

The following are some of the things that we’re wanting to add in the future:

  • Shadowing.
  • Scene management (Octree, etc).
  • Cocos2D integration (CCLayer).
  • Separate OpenGL 3+ path.

As we’ve said before, Twisted Pair are true believers of Open Source, so you can find PyGLy on our GitHub repository under a very liberal license.

Animation support for CCTMXTiledMap

Posted in Development, Programming with tags , , , , , on 2012/03/07 by Adam Griffiths

I spent today learning Objective-C and working on a small module for one of our up and coming projects.

The outcome of this was CCAnimatedTMXTiledMap. A class that adds animation support to CCTMXTiledMap in Cocos2D-iphone / Kobold2D.

Twisted Pair are true believers in support Open Source and as such we’ve published the source code to our Github repository.

Python weak references to Methods and Functions

Posted in Development, How To, Programming with tags , , on 2012/03/01 by Adam Griffiths

The ‘weakref’ module in Python cannot store pointers to methods (there are exceptions but basically you can’t).

The following is a module I’ve written to bypass this. It is essentially code from the following sites, but improved by myself for storing them in containers like set([]).

References:
[1] [2]

Continue reading

Installing Pyglet in Mac OS X

Posted in Development, Platforms, Programming with tags , , , , , on 2012/02/21 by Adam Griffiths

Pyglet is a common requirement for many Python applications, a major one being Cocos2D.

But it doesn’t work out of the box. Running a Pyglet application will result in the following error:

OSError: dlopen(/System/Library/Frameworks/QuickTime.framework/QuickTime, 6): no suitable image found.  Did find:

/System/Library/Frameworks/QuickTime.framework/QuickTime: mach-o, but wrong architecture

/System/Library/Frameworks/QuickTime.framework/QuickTime: mach-o, but wrong architecture

The following are the steps to take to get Pyglet and PyObjc installed on OS-X (tested with 10.7 Lion).

Pyglet 1.1 uses the Carbon framework, but this is not compatible with 64-bit Python installs. The Pyglet 1.2 branch has been modified to use Quartz, but no releases of this branch have seen the light of day (sigh). We must instead install Pyglet from the Mercurial repository.

The Quartz bindings require the use of PyObjc but the latest versions do not work with Pip. The patches to PyObjc’s setup.py that I’ve seen on the internet do not work for me. The following is the only method I’ve had work.

Remove any existing Pyglet install

pip uninstall pyglet

Install Pyglet from the repository

pip install hg+https://pyglet.googlecode.com/hg/

Edit: The following is no longer needed

We need to install PyObjc for the new Pyglet Quartz API. But PyObjc is horribly broken and the latest version does not install with Pip or easy_install.

We must instead install an older version.

pip install pyobjc==2.2

You should now have a working Pyglet installation.

Making .bashrc modular (and awesome)

Posted in How To, Platforms with tags , , on 2012/01/26 by Adam Griffiths

.bashrc files quickly get complex.

Putting them into revision control is handy for persistance, but not always the best for sharing when not everyone has the same environment.

So lets fix that! Continue reading

DLink 323 Ops Manual

Posted in How To, Platforms with tags , , , , , on 2012/01/17 by Adam Griffiths

I’ve created a page with a concise list of instructions for setting up and managing the DLink 323.

I’m considering moving some of the less “blog” style posts into pages to keep them in a single place.

Installing Python with pythonbrew on Mac OS-X

Posted in How To, Programming with tags , , on 2012/01/16 by Adam Griffiths

Virtualenv, virtualenvwrapper and pythonbrew are fantastic tools for developing with Python.

Using Pythonbrew to install Python on OS-X triggers some failures which prevent it being installed.

Continue reading

%d bloggers like this: