I’m trying to implement a sound spacialisation algorithm.
The convex hull of speakers is a sphere where speakers can be positionned onto.
So few questions here:
First: let’s say I want to position a speaker in a random position, this would likely be wrong value as it’s not positionned onto the hull, so how can I get the closest point onto the hull to correct the position.
Second: If I try another technic which would be to use the points of the SphereGeometryhow could I find the good rotation to align a first reference speaker to one of the point of the sphere, after that I guess I could use closest point algorithm to place the other speakers according to the other points of the sphere.
Third: I’m trying to get a triplet of speakers, if I have 4 speakers I would have 2 pairs of triplets.It’s a bit like wireframes in THREE.js.I heard about the delaunay triangulation but is there other algorithms out there.
Hello and thank you for your answer, I don’t need random points please tell me what is unclear for you. Thank you for the lookAt tip by the way I totally forgot about this function and need it to point speakers to the center of the hull
@manthrax thank you for your answer but as told before I don’t need random points.Please tell me if the following questions mentionned above are unclear to you I’ll make a pleasure explaining the to you in order to find a solution
As you can see I have a set of speakers (yellow boxes). One of the speaker is a reference speaker (giving the radius of the sphere the one on the right in this picture), which is on the sphere (the convex hull). Now I need to position my all three of my speakers onto the sphere but I need the nearest point onto the hull. I have 3 possibilities
find the closest point according to the current SphereGeometry and place my speaker at the corresponding point.
rotate the SphereGeometry to have one of the geometry’s point be equal to my reference speaker’s position then align the other speakers to one it’s closest point on the geometry
calculate the closest point onto the hull without taking in account the existing points of the geometry but instead process the point onto a generic sphere
so first and second option, I need to get points fro the geometry and third option I instead need to calculate with a more generic formula the point onto a sphere of radius r
There’s a setFromSpherical method if that helps, another option would be to add each speaker to it’s own relative parent with the same offset and then rotate each parent individually…
@Lawrence3DPK Thank you for your answer but I don’t understand both of them. What’s the aim of setFromSpherical? Are you telling me to add a speaker onto a point of the SphereGeometry then rotate it to match the desired coordinates, if so How can I rotate it for perfect match?
Here’s a simple demonstration of setFromSpherical by @PavelBoytchev
Here’s a quick demo of this suggestion for you to visualize, all three spheres (or speakers) are simply added to an empty parent, offset by a radius on the z axii and then each parent rotated on the y axii…
It’s still quite unclear what you’re trying to achieve, if you know the desired coordinates as suggested by the above quote, can you not use those desired coordinates absolutely?
Is the convexHull somewhat a “cage” you need all the speakers to be connected to at pre defined surface points? What are the desired surface points? Can you provide more details and further illustration of what you have and the result you’re after (a minimal live demo would be ideal) ?
@manthrax We defenitely don’t understand each other I guess, I do not need to have speakers equally spaced if that’s what you are trying to answer me.I need to have my speakers setted on the nearest point of the convex hull, option 1 this could be the nearest point of the spheregeometry or option 2 any point of the convex hull as long as it is onto it. Hope you understand better.Thanks a lot
This is thread is very confusing. Why do you need the geometry, can’t you just use a mathematical sphere? Also how can you possibly find a single closest point, it’s either going to be the whole sphere (if you’re in the center) or a circle (a cone intersecting the sphere). In both cases it’s infinitely many points.
If you just need to find the closest vertex on the sphere from each speaker you can use something along the lines of the following formula…
let closestVertex = null;
let closestDistance = Infinity;
let currentVertexPos = new THREE.Vector3()
const positionAttribute = sphere.geometry.getAttribute('position');
for (let i = 0; i < positionAttribute.count; i++) {
const vertex = currentVertexPos.fromBufferAttribute(positionAttribute, i);
const distance = speaker.distanceTo(vertex);
if (distance < closestDistance) {
closestDistance = distance;
closestVertex = vertex;
}
}
speaker.position.copy(closestVertex)
This is psudo code, I’m sure there’ll be a more sophisticated way but this, in theory (from what it seems like you’re asking) should position the speakers to their relative closest point on the sphere…
Otherwise you’re going to have to make some more clear definitions and illustrations of what you’re referring to as convexHull, sphereGeometry and “closest point”, eg…
“I need to move the speaker circled red to the point circled purple for each speaker”…
I don’t think it’s technically a sphere if he is looking at the mesh points like this. If he changes the resolution of the sphere it’s going to be a vastly different point probably.
@dubois I thing you are pointing a problem in my reasoning, effectively finding a closest point would be onto a circle so I’ll just leave this option.
Couldn’t find anything about topology and geosphere (if you have a link).
You’re right if I increase/decrease the spheregeometry resolution I’ll end up with different points.
This is why I would like the spheregeometry to rotate in order for one of the point to match a reference speaker.Thank you for your answer
@Lawrence3DPK This is exactly what I’ve though about but as saying to @dubois I think that one good thing would be to rotate the spheregeometry to rotate to match the already exisitng reference speaker position then move the other speakers using your algorithm.Thank you
Can you draw a picture of what you’re trying to do?
