michelez

I have a camera that moves around while looking at the center of the world. I have one object displaced from the center. As the camera moves I want to track the position of the displaced object 

. In particular I would like to track the x position in the window. I can get the world position of the object but how do I translate that position into point of view position?

I attach a patch that should make this clear

loadmess

comment

message

flonum

zl.slice

jit.iter

jit.gl.gridshape

jit.matrix

route

prepend

qmetro

loadbang

outlet

pack

unpack

vexpr

inlet

jit.gen

length

gate

jit.time.perlin

jit.time.sin

toggle

jit.gl.camera

jit.world

Hello again,
I have a camera that moves around while looking at the center of the world. I have one object displaced from the center. As the camera moves I want to track the position of the displaced object in the window. In particular I would like to track the x position in the window. I can get the world position of the object but how do I translate that position into point of view position?
I attach a patch that should make this clear


Hello again,
I have a camera that moves around while looking at the center of the world. I have one object displaced from the center. As the

track-position-in-window

Just use the lookat attribute of jit.gl.camera (lookat x y z).

unfortunately that is not what I am trying to do. I am using the lookat and locklook attribute already the way I intend to: the camera looking at the center of the world. What I need is to extract the normalized coordinates of the object within the window since I need them to do sound mapping (if the object is on the left pan left...). I think I need to get the rotation values from the camera: they are always changing because of the lookat and locklook attribute. Then I need to translate the position of the object according to the rotation of the camera to see where the object will appear on the window. Does this make sense?

unfortunately  that is not what I am trying to do. I am using the lookat and locklook attribute already the way I intend to: the camera looking at the center of the world. What I need is to extract the normalized coordinates of the object within the window since I need them to do sound mapping (if the object is on the left pan left...). I think I need to get the rotation values from the camera: they are always changing because of the lookat and locklook attribute. Then I need to translate the position of the object according to the rotation of the camera to see where the object will appear on the window. Does this make sense? 

Yes, it does. I've done something similar 

. I had a matrix with object positions to be used with jit.gl.multiple, but I needed their relative positions to the camera/ears in order to process the corresponding audio accordingly. There's a jit.gen code that does the 3D transform you want (translation and rotation) in this example patch. I hope it helps.

On a related note, I think that you may be better served by using an ambisonics package such as ICST or HOA for the panning and volume attenuation, etc. according to the position and rotation...

Yes, it does. I've done something similar in this topic. I had a matrix with object positions to be used with jit.gl.multiple, but I needed their relative positions to the camera/ears in order to process the corresponding audio accordingly. There's a jit.gen code that does the 3D transform you want (translation and rotation) in this example patch. I hope it helps. 

Thanks, this works nicely. I scaled the coordinate of the object by the distance of the camera from the center to match the position in the window. I was planning to use something like ICST or HOA, though I will use a stereo output which kinda ruins everything? Or is it still worth using ambisonics?

Also, is HOA better better/worse than ICST? I always used the HOA as it seems more thorough, though you can't use cartesian coordinates which is inconvenient.

 Also,  is HOA better better/worse than ICST?  I always used the HOA as it seems more thorough, though you can't use cartesian coordinates which is inconvenient.



track position in window