Hi, I'm stuck with this custom perspective matrix thing.

I would like to perform a custom perspective transformation (exactly like Gimp's perspective tool). Actually, I want to map a quad (the applet window) to another quad (arbitrary coordinates). I am using Sun's Java Advanced Imaging (JAI) library since it seems to provide all needed methods for such things.

The problem is, I reset the matrix and apply the matrix I just got from JAI, and I've got this ArrayIndexOutOfBoundsException. If I don't reset the matrix before applying the new one, I don't get expected results either.

Here is the matrix JAI is returning and that I would like to apply :
Code:

Perspective transform matrix
90000.0  0.0  6000000.0
0.0  80000.0  6000000.0
0.0  0.0  120000.0 

Here is what I get with printMatrix() after reseting and applying (looks ok) :
Code:

0090000,0000  0000000,0000  6000000,0000  0000000,0000
0000000,0000  0080000,0000  6000000,0000  0000000,0000
0000000,0000  0000000,0000  0120000,0000  0000000,0000
0000000,0000  0000000,0000  0000000,0000  0000001,0000 

My window's dim are 400 x 300 and I've got this exception (looks like an overflow) :
Code:

java.lang.ArrayIndexOutOfBoundsException: 120200

at processing.core.PLine.drawLine_plain_spatial(PLine.java:762)
... 

What's wrong?

Actually, I am not iterating the array myself, so there is no possible confusion. I'm just drawing a simple rect and the exception is thrown at runtime when - it seems - Processing tries to draw things out of screen : 120200 is just above 400x300 (which are my window's dimensions).

I think the values I try to apply to the matrix should be somehow scaled down but is there a rule?

Edit : I think I'm going to give up this matrix thing (just thought of another idea for simulating the perspective).