Near clipping plane cuts small objects

Question

Small objects loaded into Acrobat3D are hidden behind view near clipping plane.
The 3D annotation rendering in Acrobat3D, Acrobat Pro and Adobe Reader at versions 7.0.9, 8.1, 8.1.1, all show that the near clipping plane is set so that small objects may not be correctly rendered.
If the extent of an object is less than approximatly 0.001, it is likely to be hidden behind the front (near) clipping plane in the 3D viewport. It appears that specification of the near clipping plane numerical value which may be present in the U3D data structures are ignored, and a fixed near clip value is used.
A further sympton of this is that when the bounding box size of an object is below 0.001 in each of X,Y,Z, The bounds reported in the Part Tree panel shows zero, as values are only printed at 2 decimal digits of precision.
I would like to have near clip value be controllable from U3D 3D annotations, appropriate for small objects.
Platform:
Acrobat3D 8.1, Windows XP 32-bit
Test Case:
Take sample object (below) as ASCII VRML files (.wrl) with small
coordinate values.
Load into Acrobat3D. The object is invisible, hidden behind view near clip plane. Then sweep the right mouse slowly downwards 3 or 4 times, to "zoom out". At some point the small object will appear in the center of the window, as it is revealed on the other side of the near clip plane.
#VRML V2.0 utf8
Viewpoint { description "Initial view" position 0 0 9 }
NavigationInfo { type "EXAMINE" }
#  A tetrahedron, with 4 vertices and 4 faces and a color at each vertex.
Transform {
  translation 1.5 -1.5 0.0
  children Shape {
    appearance DEF A Appearance { material Material { } }
    geometry IndexedFaceSet {
      coord Coordinate {
        point [
           1.0e-5  1.0e-5  1.0e-5,
           1.0e-5 -1.0e-5 -1.0e-5,
          -1.0e-5  1.0e-5 -1.0e-5,
          -1.0e-5 -1.0e-5  1.0e-5,
      coordIndex [
        3, 2, 1, -1,
        2, 3, 0, -1,
        1, 0, 3, -1,
        0, 1, 2, -1,
      color Color {
        color [
          0.0 1.0 0.0,
          1.0 1.0 1.0,
          0.0 0.0 1.0,
          1.0 0.0 0.0
      colorPerVertex TRUE

Answer 1

IanC,
Have you tried using Javascript to set the clipping plane? Here's a hunk of code to set it and then move it with the Keyboard x,y,z or Shift+ x,y,z. Let me know if this helps...
//code snippet ================================
clippingPlane = scene.createClippingPlane();
//create vectors
xDir = new Vector3(3, 0, 0);
yDir = new Vector3(0, 3, 0);
zDir = new Vector3(0, 0, 3);
nxDir = new Vector3(-3, 0, 0);
nyDir = new Vector3(0, -3, 0);
nzDir = new Vector3(0, 0, -3);
//transform clippingPlane
myKeyHandler = new KeyEventHandler();
myKeyHandler.onEvent = function(event)
if (event.characterCode == 120) //x
clippingPlane.transform.translateInPlace(xDir);
console.println("move x+");
else if (event.characterCode == 121) //y
clippingPlane.transform.translateInPlace(yDir);
console.println("move y+");
else if (event.characterCode == 122) //z
clippingPlane.transform.translateInPlace(zDir);
console.println("move z+");
else if (event.characterCode == 88) //shift + x
clippingPlane.transform.translateInPlace(nxDir);
console.println("move x-");
else if (event.characterCode == 89) //shift + y
clippingPlane.transform.translateInPlace(nyDir);
console.println("move y-");
else if (event.characterCode == 90) //shift + z
clippingPlane.transform.translateInPlace(nzDir);
console.println("move z-");
else if (event.characterCode == 114) //r
clippingPlane.transform.rotateAboutYInPlace(Math.PI / 30);
//register and process
runtime.addEventHandler(myKeyHandler);