puts ""
puts "=========================================================================="
puts "OCC31016: Projection of an ellipse or a circle is a B-spline in some cases"
puts "=========================================================================="
puts ""

set startPar 1
set endPar 4.5

ellipse c 0 0 0  0.866025403784439 0 0.5  0.5 0 -0.866025403784439  20 10
trim c c $startPar $endPar
plane p 0 0 0  0 0 1
projonplane r c p 0

if {![regexp {Circle} [dump r]]} {
  puts "ERROR: Projected curve is not a circle"
}

# calculate a parametric shift on the projected curve
set pnt [ProjectCurvePointToPlaneAlongDir c $startPar p]
trim ru r
parameters ru [lindex $pnt 0] [lindex $pnt 1] [lindex $pnt 2] 0.1 shift

if {[CheckProjectionToPlane 100 c $startPar $endPar r [dval shift] [expr $endPar-$startPar+[dval shift]] p]} {
  puts ""
  puts "OK: All sample points are projected correctly"
  puts ""
} else {
  puts ""
  puts "ERROR: Projection is incorrect for some points"
  puts ""
}