Fixing angularAlignVelocity for emitters not at origin

[AndrewRayCode]

Before the angle was always pointing to the origin. Addresses issue #29. Heyo @stemkoski - can you review? (it works if he is afk)

[squarefeet]

I did exactly the same thing last night and it didn't work for me... Let me experiment again and I'll get back to you on this.

[squarefeet]

Yeah, sorry... this approach doesn't work :(

FYI: Just tested on Chrome 32, OSX 10.9.

[AndrewRayCode]

What does "doesn't work" mean? It corrected the behavior in my game. Are you changing the z position of the emitter? that's the only thing I didn't try.

[squarefeet]

The angles aren't aligned properly for the following settings:

type: 'sphere',
position: new THREE.Vector3(20, 0, 0),
radius: 20,
speed: 5,
colorStart: new THREE.Color('white'),
sizeStart: 5,
sizeEnd: 0,
particlesPerSecond: 5000,
angleAlignVelocity: 1

Taken whilst camera was circling 0,0,0 on x and z axes:

With static camera at 0,0,0

[squarefeet]

FYI: I made this test by modifying the sphere example - just changed position to 20, 0, 0

[AndrewRayCode]

maybe it "works" for me because my perspective is always top town. I'd imagine that to get actual alignment in a true 3d sphere, you would have to actually rotate the particles, not do it in the shader. Can you actually rotate particle geometry? Otherwise in the shader you'd have to take in to account camera position (I think) and pespective matrix (I think?) and do some other fun math.

[squarefeet]

Ah yeah, that might be why it works for you. @stemkoski and I discussed this very problem a while back - he had the same idea re. camera pos and matrices :)