Update upstream source from tag 'upstream/5.1.0'

Update to upstream version '5.1.0'
with Debian dir 93ca74b8b4602fce4c9c7740e0cfdde25f086673

1 files changed, 20 insertions, 4 deletions

diff --git a/app/doc/optionm.but b/app/doc/optionm.but
index c7f00d9..0c2adfb 100644
--- a/app/doc/optionm.but
+++ b/app/doc/optionm.but
@@ -138,6 +138,10 @@ The \f{Display} dialog contains items which control the display of objects on th
 
 \u000
 
+\dd \f{Draw Unconnected EndPts} - how to draw unconnected endpoints; normally, with a thick line or with a thick line in the exception color.
+
+\u000
+
 \dd \f{Draw Ties} - how to draw ties under the rails when the drawing Scale is smaller than half of the \f{Two Rail Scale}.
 
 \u000
@@ -241,13 +245,25 @@ The \f{Easement} dialog is invoked from the Options (\K{optionM}) menu.
 
 \u000
 
-\dd Radio button group with \f{None}, \f{Sharp}, \f{Normal} and \f{Broad}. Corresponding \f{Value}s for these buttons are 0, 0.5, 1.0 and 2.0. Select \f{None} to turn easements off.
+\dd Radio button group with \f{None}, \f{Sharp}, \f{Normal}, \f{Broad} and \f{Cornu}. Corresponding \f{Value}s for these buttons are 0, 0.5, 1.0, 2.0 and -1.0. Select \f{None} to turn easements off.
+
+For traditional fixed sharpness easements see \k{EasementsTraditional}, for Cornu Easements see \k{EasementsCornu}.
+
+\S2{EasementsCornu} \i{Cornu Easements}
+
+The Cornu Easements work in a different way to the other easements. They use all the space available to minimize sharpness, so you can control the sharpness for each curve you draw by the distance apart, radius and angle of the two end points.
+
+The Cornu is a mathematical curve that has the property that the curvature (inverse of the radius) varies linearly along its length. Using an open-source Cornu library written by Dr Raph Levin, we can calculate an Cornu easment to suit the end conditions of radius, curve center, angle and position. A Cornu easement can be constructed between two tracks by using the values of these parameters.
+
+To draw an cornu easement see \k{joinCornu}, to Modify it afterwards see \k{chgCornu}.
+
+\S2{EasementsTraditional} \i{Easements with Fixed Sharpness}
 
-The values \f{R}, \f{X} and \f{L} are read-only.
+The values \f{R}, \f{X} and \f{L} are read-only. They are set using the radio buttons or the \f{Value} field which can be set to 0 (No Easment) or between 0.21 (sharpest Easement) 100 (broadest Easment). 
 
 These values indicate the worst case of joining a straight track with a curve of radius \f{R}. The two tracks are separated by the offset \f{X} while the easement curve extends for \f{L/2} inches or centimeters to each side of the endpoints.
 
-The formula used to draw easements is:
+The formula used to draw non-Cornu easements is:
 
 \c          x = l * l * l / (6 * R * L)
 \e                               b   b
@@ -301,7 +317,7 @@ The font selection dialog allows selection of the font used by the text (\K{cmdT
 
 \S{cmdLayout} Layout Dialog
 
-The \f{Layout Options} dialog, displayed by the Options (\K{optionM}) menu, contains items controlling the current layout.
+The \f{Layout Options} dialog, displayed by the Options (\K{optionM}) or the File (\K{fileM} menu, contains items controlling the current layout.
 
 \dd \G{png.d/layout.png}