Minimalistic but modern OpenGL drawing for technical applications
This Python module provides the class PainterWidget, extending
PyQt5's QGLWidget class with boilerplate code neccessary
for applications which want to build a classical orthagnoal 3D world
in which the user can interactively navigate with the mouse via the
classical (and expected) Pan-Zoom-Rotate paradigm implemented via a
virtual trackball (using quaternions for rotations).
This class is especially useful for technical visualizations in 3D
space. It provides a simple Python API to draw raw OpenGL primitives
(LINES, LINE_STRIP, TRIANGLES, etc.) as well as a number of useful
composite primitives rendered by this class itself (Grid, Star,
CoordSystem, Text, etc., see files in classes/items). As a bonus,
all objects/items can either be drawn as real 3D world entities which
optionally support "billboard" mode (fully camera-aligned or arbitrary-
axis aligned), or as a 2D overlay.
It uses the "modern", shader-based, OpenGL API rather than the deprecated "fixed pipeline" and was developed for Python version 3 and Qt version 5.
Model, View and Projection matrices are calculated on the CPU, and then utilized in the GPU.
Qt has been chosen not only because it provides the GL environment but also vector, matrix and quaternion math. A port of this Python code into native Qt C++ is therefore trivial.
Look at example.py, part of this project, to see how this class can be used. If you need more functionality, consider subclassing.
Most of the time, calls to item_create() are enough to build a 3D
world with interesting objects in it (the name for these objects here
is "items"). Items can be rendered with different shaders.
This project was originally created for a CNC application, but then extracted from this application and made multi-purpose. The author believes it contains the simplest and shortest code to quickly utilize the basic and raw powers of OpenGL. To keep code simple and short, the project was optimized for technical, line- and triangle based primitives, not the realism that game engines strive for. The simple shaders included in this project will draw aliased lines and the output therefore will look more like computer graphics of the 80's. But "modern" OpenGL offloads many things into shaders anyway.
This class can either be used for teaching purposes, experimentation, or as a visualization backend for production-class applications.
Left Button drag left/right/up/down: Rotate camera left/right/up/down
Middle Button drag left/right/up/down: Move camera left/right/up/down
Wheel rotate up/down: Move camera ahead/back
Right Button drag up/down: Move camera ahead/back (same as wheel)
The FOV (Field of View) is held constant. "Zooming" is rather moving the camera forward alongs its look axis, which is more natural than changing the FOV of the camera. Even cameras in movies and TV series nowadays very, very rarely zoom.
Your graphics hardware and drivers need to support at least OpenGL version 2.1 with GLSL version 1.20.
Get and install Python3 and git. Then:
git clone https://github.com/michaelfranzl/pyglpainter
cd pyglpainter
git clone https://github.com/michaelfranzl/gcode_machine.git
pip install PyQt5
pip install numpy
pip install PyOpenGL
apt-get install python3-numpy python3-pyqt5 python3-pyqt5.qtopengl python3-opengl
python ./example.py
If you are on Windows and you are getting warnings about missing .dll's, you may need to restart Windows.
You first need to create a PyQt5 window, then add to it one PainterWidget
instance (for working code see example.py). Let's say this PainterWidget
instance is stored in the variable painter. You then can simply draw a
coordinate system:
mycs1 = painter.item_create("CoordSystem", "mycs1", "simple3d", 12, (0, 0, 0))
This means: Painter, create an item of class CoordSystem labeled "mycs1"
with the shader program called "simple3d". Scale it by 12 and put its origin to
the world coordinates (0,0,0).
Copyright (c) 2015 Michael Franzl
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.