Welcome to python-cg’s documentation!¶
python-cg¶
What is python-cg?¶
python-cg is a Python wrapper for NVidia Cg Toolkit runtime. I’ve started it because I like Python, I like NVidia CG and I want to to do some computer game/3d graphicsprototyping and research. Also I still find C++ counterproductive as far as my needs are concerned and I don’t want to waste my time doing boring stuff. Programming in Python is fun.
I know about some projects that were meant to bring CG to Python but as far as I know they’re history now.
Project is hostead at GitHub: https://github.com/jstasiak/python-cg.
What’s the state?¶
The project is in very early development stage. Overview of what’s supported right now:
- Cg contexts
- creating
- destroying
- CgFX effects
- creating from file
- creating directly from source code
- accessing effects` techniques and their passes
- accessing effect parameters with their names, semantics and parameter-specific metadata (rows, columns etc.)
- setting sampler parameters and most of numerical parameters
What doesn’t work at the moment and there’s no plan to implement it:
- everything that’s left (well, until I decide I need some of it or someone else does that)
Requirements¶
This project requires:
- NVidia Cg Toolkit ≥ 3.0
- Python interpreter (+ development files):
- 2.x ≥ 2.6, or
- 3.x ≥ 3.2
- C and C++ compiler
Python packages required to build and install python-cg:
- Cython ≥ 0.18
- numpy
To build documentation/run tests you also need:
- Mock ≥ 1.0
- Nose ≥ 1.2
- Sphinx ~ 1.2 (development version)
Documentation¶
Pregenerated documentation can be found at https://python-cg.readthedocs.org/en/latest/.
You can also build documentation all by yourself by calling:
sphinx-build -b html docs docs/build/html
Generated HTML files are placed in docs/build/html/ directory.
Important information¶
- This project works with OpenGL and OpenGL only
- It uses row-major matrices by default, just like numpy does
Quickstart¶
First you need to create an instance of CG class and use it to create new Context:
from cg import CG
cg = CG()
context = cg.create_context()
We want to use an effect to render some stuff so we’re gonna create Effect from file:
effect = context.create_effect_from_file('effect.cgfx')
Note
This assumes that you have a file named effect.cgfx and that it contains a valid CG effect.
We now have access to Effect’s techniques and parameters:
for technique in effect.techniques:
# ...
for parameter in effect.parameters:
# ...
For the sake of simplicity let’s say we have a parameterless effect with only one Technique:
technique = effect.techniques[0]
Now we can access technique’s passes. Each Pass has methods begin() and end() and the actual drawing has to take place between a call to begin and end:
gl.glClear(gl.GL_COLOR_BUFFER_BIT)
for pass_ in technique.passes:
pass_.begin()
gl.glBegin(gl.GL_TRIANGLES)
gl.glVertex3f(-0.5, -0.5, 0)
gl.glVertex3f(0.5, -0.5, 0)
gl.glVertex3f(0, 0.5, 0)
gl.glEnd()
pass_.end()
# swap buffers
You can find complete, runnable example application in example directory. Please note that it requires (in addition to python-cg requirements):
Development version of SFML 2
Python packages listed in example/requirements.txt:
pip install -r example/requirements.txt
Then to run the example:
python setup.py build_ext --inplace
PYTHONPATH=. python example/main.py