Develop Reference

VTK Render Mouse Interaction (Python)

I want to visualize one or more STL file(s) using a vtk render viewport inside my application. I was able to get it all running with this example here: https://kitware.github.io/vtk-examples/site/Python/IO/ReadSTL/
My question is as follows: I have a mouse to control it and it is just unbelievable how bad default the controls of the camera are. It is almost impossible to get the model rotated intentionally or focus on a certain part. I am confused as I could not find any topic here or elsewhere discussing this. Normally I would read through other threads to find an answer, but there doesn't seem to be any. So, maybe you can point me to an approach or even certain functions of how I can change these settings, that would be really great! Basically I want to mimic the camera behavior of say, Paraview or a common CAD tool. Like zooming with mouse wheel, rotating with RMB and holding down the wheel to pan.
Some background on my project: I have written a python program and created a quite ok UI using tkinter. However, recently I was thinking of rewriting some basic parts of it and also upgrading everything visually and in terms of handling. So, I want to move to Qt widgets and, there shall be a VTK rendering viewport inside my application to show some of the stuff that can be interacted with.

I was able to find a solution in the tutorials. By explicitly defining the vtkInteractorStyle with
style = vtk.vtkInteractorStyleTrackballCamera()
The handling is just as I wanted it to be.

Is there a comprehensive multitouch library for Python?

I'm trying to embed multitouch events into my wxPython GUI, however i'm a bit lost as to the best approach.
Currently, I have a TUIO server which transmits the multitouch events to be captured. I then use the pytuio library to receive the multitouch events in a separate thread for my GUI. My GUI is composed of a wxFrame with multiple matplotlib panels and a single OpenGL panel.
The problem is that I have had to manually write code to determine how many fingers are being used, the locations and the touch type. I then send a custom event which can be received by my GUI.
This works fine for the matplotlib panels (albeit I have to provide a very small constant offset to the reported location of the fingers), but for the OpenGL panel the finger locations seem to be incorrect. This is a problem as the offset of the touch locations in the OpenGL panel is not even a constant, it seems to vary depending where on the panel the touch event occurs. So I cannot compensate for it.
I feel like there must be a more comprehensive multitouch library, which does all the hard work determining the number of fingers and touch type (tap, double tap, drag, release etc). And possibly would overcome my issue with the OpenGL panel. I have looked but I've not seen a library which can distinguish the touch type etc., they just seem to provide a list of the number of fingers and the locations.

The only comprehensive GUI library supporting:
Python
More than one OS
Multitouch
is Kivy. I was able to cobble together something which works for Windows 7 and higher and wxPython (by extracting the relevant part from Kivy for processing WM_TOUCH events), so in principle it could be done. But none of this would solve your specific problem.

Python Script (main) + Blender "face" animation

SO I am infact doing something very similar to this user posts:
https://stackoverflow.com/questions/6800292/python-ai-and-3d-animation
but it has no answers and I couldn't contact the user.
Basically I have a functioning python script that answers me with an action accordingly to my voice command. (Fetch emails, weather forecast, turn lights ON/OFF, etc), it has been made using the pyspeech library which is pretty darn good.
Now I want to give my programm a "face"! I thought about modelling the face with Blender (have some knowledge and would build up on it) and I know I could animate it, so the lips move and such.
So I want to know if it is at all possible to:
Load the "face" that I made from blender from my main python script (so when my programm start the face would be there on the screen too)
Run from the script the animations such that when for example when my programm says "You're welcome" I would run the animation that the lips move on the face to simulate it is speaking.
I know that blender has a good python integration (maybe correct is to say it is built on?) and that is why I thought it would be a good program to use.
Hope someone can help and tell me if that is at all possible and maybe show me some right way to go, my googling just showed me always python scripting with Blender which is not what I exactly need here... I think...
Cheers,
Flavio

Indeed, what you want is possible.
If all you want is to play pre-rendered animation videos based on decisions on your program, any GUI that allows you to embedd and play video in a widget will do for your application.
You could rool out your own GUI using Pygame (which has video support, but you will need one of the "minor" more or less "amateur" widget toolkits made for pygame to make up the remaining of your application, as pygame is pretty low level.
On a higher level, although I'had not embedded video, I think you could go with PyQT4 (googled a bit, not that many examples either, buthints that there are eamples in QT4 source) or GTK+ (the samething, it looks like there are more examples).
Another option would be to build your application to run inside the Blener Game Engine itself - It offers both a high level Toolkit, and ways to customize behaviors to user actions (even without coding).
The major drawback in doing this is: I don't know which are the options to distribute an application that needs Blender Game Engine nowadays - your users will need to install Blender (but it is likely Blender folks made an easy way to jhandle this).
On the upper hand: you get the most flexibility, it would even be possible to render some sequences in realtime (as opposed to pre-rendered videos) in your app.
One thing: Blender nowadays use Python 3.x - if the other libraries you need are Python 2, you willl need to make one different process for the GUI inside Blender, and exchange data with your application's backeend in Python 2 (for example using jsonrpc or xmlrpc - that is enoguh simple in Python).

Python, transparent window with a red outine of a rectangle

Hi I am new to this whole coding thing I was suggested to use Python. The version I have now is 2.7. I need help with making a transparent window to the copacity of 100 so that you can actually see through it and I also want to know how to make a fairy thick, out line of a rectangle in the colour red.
Help me please :S Thanks!

Unfortunatelly, there is not such an easy thing as sa "trasnparent window" - althougmodern widnow managaers do have various opacity controls for the windows, those just affect the windows as a whole - and do not integrate at all with the program running "inside" the windows. There may even be, for some of them, a way to call functions to explicitly set up the opacity level of a given window, but I don't think it willbe possible for all of them.
That said, it is possible to get grab of the "root" window and draw directly on the screen - -bypassing the window manager. There are APIs for that at least on Windows and Linux (you have to mention in what operating system you need that working) - but it will amount to not a trivial research work, since this is not what is expected of a "well behaved app" - for which the GUI toolkits are written and documented. You will need to write xlib code in Linux, and directly call win32 api's on windows - both are possible from Python - as possible as under-documented.
And once you get to draw the rectangle, since you are bypassing the window manager, you willhave to care about every low-level detail of your app: mouse event handling, screen-redrawing (and notifying the system of drawing taking effect over other windows), and so on.

2D animation in Python

I'm writing a simulator in Python, and am curious about options and opinions regarding basic 2D animations. By animation, I'm referring to rendering on the fly, not displaying prerendered images.
I'm currently using matplotlib (Wxagg backend), and it's possible that I'll be able to continue using it, but I suspect it won't be able to sufficiently scale in terms of performance or capabilities.
Requirements are:
Cross-platform (Linux, MacOS X,
Windows)
Low complexity overhead
Plays well with wxpython (at least won't step on each other's toes unduly)
Interactivity. Detect when objects are clicked on, moused over, etc.
Note that high performance isn't on the list, but the ability to handle ~100 bitmap objects on the screen would be good.
Your thoughts?

I am a fan of pyglet which is a completely self contained library for doing graphical work under win32, linux, and OS X.
It has very low overhead, and you can see this for yourself from the tutorial on the website. It should play well with wxpython, or at least I seem to recall posts to the mailing list about wxpython and pyglet being used together.
It however does not offer selection of objects via mouse clicks - this you will have to handle yourself. Generally speaking for a 2D application this is not too difficult to do.
mactorii is an OS X application of mine written in pure python+pyglet, and has some basic animation (scrolling) and click detection. It doesn't use wxpython, but perhaps it will give you an idea of what is involved. Note however mactorii is using the old pyglet api, so the run loop I have in there is obsolete. I will get around to updating it one day... :P

You can try pygame, its very easy to handle and similar to SDL under c++

Arcade works on any platform with OpenGL 3.3+ (i.e. not the Raspberry Pi, but most other platforms). Although it's intended for simple games, Arcade offers great bitmap and sprite handling, as well as simple graphics primitives such as rectangles, arcs and circles.