Brush aspect ratio is strange, doesn't match documentation
GIMP version: 2.10.4
Operating System: macOS High Sierra 10.13.6 (17G65)
Package: download from gimp.org
Description of the bug
The brush aspect ratio setting doesn't change the brush shape as the documentation says, or as aspect ratio is normally defined.
Reproduction
Is the bug reproducible? Always
Reproduction steps:
- Go to brushes dialog.
- Pick the big circle brush "2. Hardness 100"
- Set size to 50 pixels and aspect ratio to 2
- Click to draw with the brush
Expected result:
Circle should have 50 pixels width and 25 pixels height. (Or maybe 100 pixels width, 50 pixels height.)
Actual result:
Circle has 50 pixels width and 17 pixels height. This is an aspect ratio of 2.9, not 2.
Additional information
All values of aspect ratio are strange. 0 gives a normal aspect ratio, which should be "1". Other brushes have similar problems. E.g. single pixel brush, size 10, aspect ratio 1: size drawn is 7x3. Expected size 10x10.
Documentation says "Aspect ratio This parameter controls the brush Width/Height ratio. A diamond with a 5 pixels radius and an Aspect Ratio = 2, will be flattened with a 10 pixels width and a 5 pixels height (1.0-20.0)."
Bug #486 on aspect ratios is potentially related but different.