Game Development Reference
In-Depth Information
Figure 6-11.
Another image comparison
Because the absolute difference is calculated by subtracting one set of pixels from the other, the result shows
you where there are rendering deviations. (If the images are exactly the same, the absolute difference will come out
black, so the blacker the absolute difference, the more the images match.) The relative difference is the grayscale
representation of those absolute differences normalized. The magnitude of the greatest difference is shown as white,
which means that anywhere you see white, the relative difference image differs most from the comparison image.
Troubleshooting
You will find troubleshooting help for specific tests and conditions within the GUI test reports. However, here are
some general tips.
Setup
If the test suite will not launch, run the Python script from the command line to see error reports. If wx or OpenGL
is mentioned, make sure you installed both packages into the correct Python version. If your script code doesn't
compile, the suite will not launch. Rendering .
PNG
images at a resolution greater than 512 x 512 could cause memory
problems. If your output document is significantly larger than your input document, you will get a warning. You won't
fail the test, but do follow these recommendations to avoid excessive growth of documents:
•
Strip non-significant leading/trailing zeros from numbers in the output.
•
Keep XML output indentations to a reasonable minimum. Two spaces or one hard tab per
level is sufficient.
•
Avoid indentations when writing large arrays or lists of numbers. Write them as a single long
line of text with separating spaces or break them into multiple non-indented lines.
