Transform Matrix Problems
I was recently working on a script run particle system to provide a realistic fireing effect from a gattling gun. The script was setup to track the positions of each of the 6 barrels, and when any of the barrels pass over the particle emitter it would trigger to fire a single bullet as well as a muzzle flash. The issue I ran into was when I tried to align point helpers positioned on each barrel tip with the particle emitter.
I first tried the align tool, and then later in the listener did a direct transform matrix replacement to get the alignment directly ontop of one another when I found the matrix problems. Both methods came to the same result, a small inconsistancy within the transform matrix of the objects which caused comparing positions to return false. I have since found a better way to handle the position detection, but my question is, is this a documented problem with 3DS MAX or a fluke I came across?
Below I've provided a test that I ran in in the listener to document the problem. You'll notice the inconsistancy in many of the matrix variables in the 5th or higher decimal place. This test was done after a direct replacement with
$BarrelPoint03.transform = $PF_MuzzleFlash.transform
$BarrelPoint03.transform
(matrix3 [0.13576,0.984956,-0.10691] [-0.139704,-0.087799,-0.986293]
[-0.980843,0.148834,0.125682] [-4.21852,-2.75201,45.2194])
$PF_MuzzleFlash.transform
(matrix3 [0.13576,0.984957,-0.106909] [-0.139705,-0.0877978,-0.986293]
[-0.980843,0.148835,0.125684] [-4.21852,-2.75201,45.2194])
$BarrelPoint03.pos
[-4.21852,-2.75201,45.2194]
$PF_MuzzleFlash.pos
[-4.21852,-2.75201,45.2194]
$BarrelPoint03.pos == $PF_MuzzleFlash.pos
false
test = $BarrelPoint03.pos / $PF_MuzzleFlash.pos
[0.999999,1,1]
test[1] --This one isn't surprising as the 9's surely continue indefinitely
0.999999 -- So testing against a limited value will not return true.
test[1] == 0.999999
false
test[1] - 1.0
-6.55651e-007 -- 0.000000655651
test[2]
1.0
test[2] == 1.0
false
test[2] - 1.0
-4.17233e-007 -- 0.000000417233
test[3]
1.0
test[3] == 1.0
false
test[3] - 1.0
1.19209e-007 -- 0.000000119209