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

set projDir { 1 1 1 }
set startPar 1
set endPar 4.5

circle c 0 0 0  10
trim c c $startPar $endPar
plane p 0 0 0  1 0 1
projonplane r c p [lindex $projDir 0] [lindex $projDir 1] [lindex $projDir 2] 0

if {![regexp {Ellipse} [dump r]]} {
  puts "ERROR: Projected curve is not an ellipse"
}

# calculate a parametric shift on the projected curve
set pnt [ProjectCurvePointToPlaneAlongDir c $startPar p $projDir]
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 $projDir]} {
  puts ""
  puts "OK: All sample points are projected correctly"
  puts ""
} else {
  puts ""
  puts "ERROR: Projection is incorrect for some points"
  puts ""
}