How convert meshes position? (cannon -> three || three -> cannon)

[nedcrow]

I made the land tilted 45 degrees.
And gravity too 45 degrees.

I want see stacked boxes at center of ground.
When this time, how convert position of plane or ground?

this like a,
const posY = useRef( convertY(plane.position, y) );
const posZ = useRef( convertZ(plane.position, z) );

return <>
. <Box position ={[x,posYs, posZ]} />
</>

sandbox:
https://codesandbox.io/s/r3f-cannon-instanced-physics-z1iwd?file=/src/index.js

[codynova]

Hi @Nedrow, I'm having trouble understanding your question. I can see how you've set the gravity at 45 degrees, but I don't understand what you are trying to achieve with positions.

[nedcrow]

Hi @codynova , I want multiple drop box. but boxes should straight align.

example 45 degrees,
ground position = [0, 0, 0]
box & ground rotation = [Math.PI/4, 0, 0]
box1 position = [0, 0 + 1/root2, 1/root2];
box2 position = [0, 2/root2, 2/root2];

and 50 degree, 75 dgree.. so I was wondering if there is an easy way (or formula).