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o Little readme updates.

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This commit is contained in:
Henner Zeller 2016-09-05 18:41:06 -07:00
parent da0973cea5
commit d4225c7ecd
2 changed files with 20 additions and 7 deletions
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7
examples-api-use/README.md
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@ -200,7 +200,8 @@ You might choose a different physical layout than the wiring provides.
Say you have 4 displays with 32x32 and only a single output
like with a Raspberry Pi 1 or the Adafruit HAT -- if we chain
them, we get a display 32 pixel high, (4*32)=128 pixel long. If we arrange
the boards in a square, we get a logical display of 64x64 pixels:
the boards in a U-shape so that they form a square, we get a logical display
of 64x64 pixels:
<img src="../img/chained-64x64.jpg" width="400px"> In action:
[![PixelPusher video][pp-vid]](http://youtu.be/ZglGuMaKvpY)
@ -209,7 +210,7 @@ the boards in a square, we get a logical display of 64x64 pixels:
So the following chain
[<][<][<][<] }- Raspbery Pi connector
is arranged in this U-shape
is arranged in this U-shape (on its side)
[<][<] }----- Raspberry Pi connector
[>][>]
```
@ -229,7 +230,7 @@ Sometimes you even need this for the panel itself: In newer panels
(often with 1:4 multiplexing) the pixels are often not mapped in
a straight-forward way, but in a snake arrangement for instance.
The CanvasTransformer allows you to work around that (I recently have gotten
some of these to test myself. This will be a new multiplexing option).
some of these to test myself. This will be a new multiplexing option soon).
Back to the 64x64 arrangement:

20
python/README.md
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@ -6,12 +6,15 @@ Building
In the root directory for the matrix library simply type:
### Python 2
```shell
sudo apt-get update && sudo apt-get install python2.7-dev python-pillow -y
make build-python
sudo make install-python
```
### Python 3
You can also build for Python 3:
```shell
@ -20,8 +23,17 @@ make build-python PYTHON=$(which python3)
sudo make install-python PYTHON=$(which python3)
```
Speed
-----
### PyPy
The cython binding to PyPy seems to be somewhat working but extremely slow (20x
slower even than the regular Python binding, 160x slower than C++), so this is
not recommended. From glancing at the docs, the library might need to
be bound via **[CFFI](https://cffi.readthedocs.io/)** first. If anyone has
experience doing that, please consider preparing a pull request (ideally in
a way that it can be used as well for Python2/3 and does not change the
interface of the current Python binding).
Performance
-----------
The simplicity of scripting comes at a price: Python is slower than C++ of course.
If you have to do a lot of pixel updates in your demo, this can be too slow
depending on what you do. Here are some rough numbers for calling `SetPixel()`
@ -34,8 +46,8 @@ in a tight loop:
corresponding C++ program. Given that the Pi-1 is already about 1/10 the
speed of a Pi-3, this almost makes Python unusable on a Pi-1
(~0.015 Megapixels/s Python vs. ~0.36 Megapixels/s C++)
* Also interesting: Python3 is about 40% slower than Python2.7 (measured on
a Pi-3). So if you can, stick with Python2.7 for now.
* Also interesting: Python3 is a little bit slower than Python2.7.
So if you can, stick with Python2.7 for now.
* The good news is, that this is due to overhead per function call. If you
can do more per function call, then this is less problematic. For instance
if you have an image to be displayed with `SetImage()`, that will be faster