[gl4java-usergroup] Questions with GLCanvas and Selection

[<dom...@so...>]

Hi there, 

I've two questions about GLCanvas and Selection. 

1. Instead of having the Canvas keeps redrawing itself (that's why I'm not 
using GLAnimCanvas), I want to take over the control of the rendering 
process so that it only redraws when I ask it to (e.g. when the mouse or 
keyboard is pressed).
I've done this successfully in GLUT, where I only call glutPostRedisplay() 
when mouse/keyboard events are triggered.
In GL4Java, I tried to archieve this by using a GLEventListener attached to 
GLCanvas. I attach my mouse and keyboard listener classes to glDrawable 
under the init function of my GLEventLister, and try to see if any control 
is pressed in the postDisplay() function. If so, glDrawable.repaint() is 
called to redraw the window.
The problem is that it only listen to events when I left click on the mouse! 
For example, I setup the 'up' key to scroll the screen upwards. The canvas 
only starts redrawing when I press/hold the key and click the mouse once.
What is the problem of this? Would subclassing GLCanvas instead of using 
GLEventListener help? 

2. I have a selection routine and it works well with GLAnimCanvas. Once I 
switched to GLCanvas (I'm using GLEventListener, therefore the only change 
to code by this is the line that declaring the canvas, plus some GLAnimCanva 
specific code such as setFpsSleep()), the selection no longer works. I 
tracked the variables and found that in my selection routine, the viewport 
values got by glGetIntegerv are all zero! Where I tested it in the reshape 
function and the values are correct.
Again, what's the problem causing this? Would that subclassing stuff help 
again? 

Thank you very much! 

Regards,
Dominic