Created attachment 1594 [details]
new window with all 3 lines, only the opaque line remains after resizing the window.
if you plot something like
using the "grid" package, all 3 lines are displayed correctly upon opening a new device - if the graphics window is resized, the transparent elements disappear (see screenshot). line width, etc. do not affect this behavior.
resizing the graphics device works fine under debian and kubuntu, so i guess it's windows-specific.
Created attachment 1821 [details]
disappearing semitransparent lines using grid
# this bug is still reproducible in R 3.2.0 and R-devel.
# short code example to show the behavior of base graphics vs. grid.
# setting up colors
y <- seq(0, 255)
w <- abs(seq(-255, 255, length.out = 256)) # transparency
greenred <- rgb(y, 255-y, y*0, alpha = w, maxColorValue = 255)
# lines with alpha < 1 are displayed when resizing a "base graphics" window:
plot(NA, type = "n", xlim = c(0, 255), ylim = c(0, 1))
segments(y, 0, y, 1, col = greenred)
# in "grid", resizing the window causes all alpha < 1 lines to disappear:
pushViewport(viewport(xscale = c(-.1, 1.1), yscale = c(-.1, 1.1)))
grid.segments(y/255, 0, y/255, 1, gp = gpar(col = greenred), default.units = "native")
This is not reproducible on ...
system x86_64, linux-gnu
status Under development (unstable)
svn rev 67980
version.string R Under development (unstable) (2015-03-11 r67980)
nickname Unsuffered Consequences
(In reply to Paul Murrell from comment #2)
> This is not reproducible on ...
> > R.version
> platform x86_64-unknown-linux-gnu
> arch x86_64
> os linux-gnu
> system x86_64, linux-gnu
> status Under development (unstable)
> major 3
> minor 2.0
> year 2015
> month 03
> day 11
> svn rev 67980
> language R
> version.string R Under development (unstable) (2015-03-11 r67980)
> nickname Unsuffered Consequences
this problem is windows-specific - debian, kubuntu, etc. work fine (couldn't test it on a mac). just reproduced this on another windows machine:
system x86_64, mingw32
svn rev 68343
version.string R version 3.2.0 Patched (2015-05-07 r68343)
nickname Full of Ingredients