This selection improvement feature is hidden behind the advanced
configuration key "PcbSelectionVisibilityRatio". It is turned off (1.0)
by default. Value values are from 0.0 to less that 1.0. From testing,
using a value between 0.1 and 0.3 produces the best results.
This fix uses normal alpha blending described in the link below. The
current design only uses the alpha of the object's color. It could be
improved by doing a full color alpha blending but using the color alpha
alone seems to result in satisfactory results.
https://en.wikipedia.org/wiki/Alpha_compositing
Fixes https://gitlab.com/kicad/code/kicad/-/issues/16126
The old bottom to top layer stack up sequence from back to front layer was
only used for plotting so it was renamed appropriately. This will be used
for future board object select disambiguation improvements.
stdlib checks do not allow dereferencing the first element of a vector
when there are no elements in the vector (regardless of whether we have
allocated memory for them). This whole function is rather
over-engineered, setting up multiple allocations and branches depending
of the string size. This commit reduces the function to the actions
needed (get the string size, print it into the output)
Wayne Stambaugh
Seth Hillbrand
Marek Roszko