What: 3dcanvas (DRH)
 Where: http://3dcanvas.tcl.tk/ 
 Description: This widget implements a high-level canvas type interface
        to OpenGL.
        The program describes a scene as a bunch of polygons and lines with
        various properties (color, transparency, etc) and the position of lights
        and the camera.  Simple commands allow the camera to moved to fly
        through the scene.
 License: BSD
 Status: Under active development
 Updated: 2005-08-17
 Contact: mailto:[email protected] 

 What: Qanim - tclogl Animation Demo 
 Where: [L2 ]
 Description: This code demonstrates a 3d canvas built using Tcl code on top of tclogl.
 License: Free for non commercial purposes.
 Status: Proof of concept, other tclogl code under development.
 Updated: 2005-10-22
 Contact: Philip Quaife

 What: 3dcanvas (Peter Loborg)
 Where: http://www.ida.liu.se/~petlo/3D_canvas/  (dead link)
 Description: This widget implements a three dimensional space in which
        structured graphics can be rendered. A 3dcanvas displays any
        number of items, which may be things like spheres, polygons,
        lines and prisms.  Items may be manipulated (e.g. moved or
        re-colored) and commands may be associated with items in much
        the same way that the bind command allows commands to be bound
        to widgets.  The 3dcanvas also contains a powerful grouping
        mechanism for manipulating several spatially related objects as
        one.  The objects in a 3dcanvas are stored in a hierarchical
        database together with associated relations and attributes.
        This hierarchy is constructed using a special item type called
        the group item, which is capable of containing other items
        including group items. In the 3dcanvas, all items have their
        own coordinate system, which is relative to that of its parent
        group (this is the group in which the item is currently
        placed). All transformations such as scaling or rotating is
        performed on this local coordinate system. This means that if a
        group is rotated, its coordinate system.
        3dcanvas is an old project (Tk4.2) introduced by Peter Loborg.
        The small graphics kernel doesn't depend on a third party library.
 License: LGPL
 Status: No longer maintained
 Updated: 12/1996 (but v1.0 released 12/2003)
 Contact: mailto:[email protected] 

# objviz-3dc.tcl
 # Author: Gerard Sookahet
 # Date: 2004-01-04
 # Description: Simple .obj (Alias-Wavefront graphics file format) viewer

 load c:/tcl/lib/dddcanvas/dddcanvas.dll

 bind all <Escape> { exit }

 # Parse .obj file format
 proc ObjReader { f } {
     global G

  if {$f == ""} then return

  .c delete all
  set nv 0
  set nf 0
  array set tcoords  {}
  array set tconnect {}

  set fp [open $f r]
     set data [read $fp [file size $f]]
  close $fp

  set data [split $data "\n"]
  foreach line $data {
         if {[lindex $line 0] == "v"} then {
           # --- vertex
           incr nv
           set tcoords($nv) [lrange $line 1 end]
         } elseif {[lindex $line 0] == "f"} then {
           # --- face
           #     JAG,04-Mar-2005
           #     Updated to handle face record containing "vt" and "vn" flags
           #     So, "f 1 2 3" or "f 1/1/1 2/2/2 3/3/4 4/4/3" should now work...
           
           #     next line commented out as it does not handle vt and vn flags
           #set tconnect($nf) [lrange $line 1 end]
           incr nf
           foreach item [lrange $line 1 end] {
                lappend tconnect($nf) [lindex [split $item "/"] 0]
           }
         }
  }

 # Create group items and display lines
  set G [.c create group]

  for {set i 1} {$i <= $nf} {incr i} {
     set lcoords {}
     foreach j $tconnect($i) { lappend lcoords $tcoords($j) }
     .c addgroup $G items [eval .c create line [join [concat $lcoords] " "] -fill blue]
  }

 }

 # Simple rotation animation for phi and theta angle
 proc Animate {} {
     global G

  .c phirot $G 2
  .c thetarot $G 2
  after 50 Animate
 }

 proc BrowseFile { dir filter } {

  switch $filter {
        obj  { set file_types {
                    { {Obj files} {.obj} }
                    { {all files}  * }
             }
        }
  }

  set file [tk_getOpenFile -filetypes $file_types \
                           -initialdir $dir \
                           -title "$filter File"]
  if {$file != ""} { return $file } else { return ""}
 }

 proc Main {} {
     global scx scy scz
     global somega sphi stheta
     global vdist
     global G

  set scx 0
  set scy 0
  set scz -20
  set vdist 400

  wm title . "Objviz with 3dcanvas"
  3dcanvas .c -bg black -width 700 -height 500
  pack .c -side top

  set f0 [frame .f0]
  pack $f0

  set f1 [frame $f0.f1]
  scale $f1.scx -from 200 -to -200 -length 400 -label "X translation" -orient horiz \
                -showvalue true -variable scx -command {.c configure -ox}
  scale $f1.scy -from 200 -to -200 -length 400 -label "Y translation" -orient horiz \
                -showvalue true -variable scy -command {.c configure -oy}
  scale $f1.scz -from 1000 -to -1000 -length 400 -label "Z translation" -orient horiz \
                -showvalue true -variable scz -command {.c configure -oz}
  scale $f1.vd -from 3000 -to -1000 -length 400 -label "View distance" -orient horiz \
                -showvalue true -variable vdist -command {.c configure -viewdistance}
  eval pack [winfo children $f1]

  set f2 [frame $f0.f2]
  scale $f2.scomega -from 180 -to -180 -length 180 -label "Omega angle" -orient horiz \
                -showvalue true -variable somega -command {.c configure -omegaangle}
  scale $f2.sphi -from 180 -to -180 -length 180 -label "Phi angle" -orient horiz \
                -showvalue true -variable sphi -command {.c configure -phiangle}
  scale $f2.stheta -from 180 -to -180 -length 180 -label "Theta angle" -orient horiz \
                -showvalue true -variable stheta -command {.c configure -thetaangle}
  eval pack [winfo children $f2]

  set f3 [frame $f0.f3]
  button $f3.bloadobj -text "Load obj" -width 9 -command {ObjReader [BrowseFile [pwd] obj]}
  button $f3.bromega -text "Omega rotate" -width 9 -command {.c omegarot $G 8}
  button $f3.brphi -text "Phi rotate" -width 9 -command {.c phirot $G 8}
  button $f3.brtheta -text "Theta rotate" -width 9 -command {.c thetarot $G 8}
  button $f3.banim -text Animate -width 9 -command {Animate}
  button $f3.babout -text About -width 9 -bg grey -command {About}
  button $f3.bquit -text Quit -width 9 -bg grey -command exit
  eval pack [winfo children $f3]

  pack $f1 $f2 $f3 -side left
 }

 proc About {} {
  set w .about
  catch {destroy $w} ; toplevel $w
  wm title $w "About this demo"
  message $w.msg -justify center -aspect 250 -relief sunken \
                 -text "3dcanvas demo: a simple .obj viewer\n\nGerard Sookahet\n\
                        2004-01-04"
  button $w.bquit -text Quit -command {destroy .about}
  eval pack [winfo children $w]
 }

 Main