How can I transform a 3D world coordinate to a 2D device coordinate?

Question

I have been working with Java 3D for a few months and I can create a scene graph and display it. Now, I want to transform a 3D world coordinate to a 2D device coordinate. I don't want to draw the 3D point in the scene, I just want to know what the 2D coordinates would be. Does anyone know what sequence of transformations must be made to do this?

Answer 1

Thank you for your reply. I used your code and it solved most of my problems. However, I can't get it to apply a perspective projection to the point in question.
I took the following line of code from your response above.
view.getCanvas(0).getPixelLocationFromImagePlate(somePointInNode, awtPoint);From your code, and the javadoc that I've read, it appears that it should perform a perspective projection, but in my case it doesn't.
I have included output from my program below. I wrote a program that displays the x, y, and z axes on a Canvas3D. The viewpoint is looking down the z-axis with the positive x-axis pointing to the right and the positive y-axis pointing up. I then used your code to compute 2D points at the origin and along each of the three axes (calls 1-4 in my output). On the Canvas3D, the origin and the point along the positive z-axis are at two distinct locations, as one would expect of a perspective projection. However, when I compute the 2D location using your code, the 2D points are identical, as one would expect of a parallel projection. My view's projection policy is PERSPECTIVE_PROJECTION, but as my output below shows, the transformation from somePointInNode to awtPoint in calls 1 and 4 appears to be created as if it is a parallel projection. It is as if the z component is ignored. Why? Am I doing something wrong?
My output:
projection policy = perspective projection
call 1:
somePointInNode
origin: x=0.12699998915195465 y=0.15931445360183716 z=0.0
awtPoint
x=445.999961562044 y=435.4999675525455
call 2:
somePointInNode
x-axis: x=0.2528710961341858 y=0.15931445360183716 z=0.0
awtPoint
x=891.9999469321543 y=435.4999675525455
call 3:
somePointInNode
y-axis: x=0.12699998915195465 y=0.2851855605840683 z=0.0
awtPoint
x=445.999961562044 y=-10.500017817564867
call 4:
somePointInNode
z-axis: x=0.12699998915195465 y=0.15931445360183716 z=0.12587110698223114
awtPoint
x=445.999961562044 y=435.4999675525455