orient grids to origin by edge

[papsphilip]

I have some randomly rotated grids in 3d space that i'd like to orient to the origin on XZ plane (flat on the ground) and have the longest edge align with the Z axis.

How can i figure out each grid's transform and orient and reset it. Controlling the way it gets oriented (longest edge) is important for UVing later
 

[animatrix]

Hi,

One way would be like this:

vector p0 = point ( 1, "P", 0 );
vector p1 = point ( 1, "P", 1 );
vector p2 = point ( 1, "P", 2 );

vector dir0 = p1 - p0;
vector dir1 = p2 - p0;

vector dir = dir0;
if ( length2 ( dir1 ) > length2 ( dir0 ) )
    dir = dir1;
    
@P -= p0;

vector n = primuv ( 1, "N", 0, 0.5 );

matrix3 m = maketransform ( normalize ( dir ), normalize ( n ) );

@P *= invert ( m );

 

[tamagochy]

You can use this wrangle in foreach 

// Build Matrix From Edge
int pts[] = neighbours(0,@ptnum);
float dists[];
vector dirs[];
foreach(int pt; pts){
    vector pos = point(0,"P",pt);
    vector dir = pos-@P;
    float dist = length(dir);
    append(dists,dist);
    append(dirs,normalize(dir));
}
dirs = reorder(dirs,argsort(dists));
vector z = dirs[-1];
vector y = dirs[0];
vector x = cross(z,y);


matrix m = set(x, y, z);

translate(m,@P);

4@m = m; 

And then choose point 0 take matrix and make invert multiplication for the grid

 

[papsphilip]

thank you!

i m not sure if i implemented your methods correctly but they are not working

orient planes.hip

Edited December 9, 2020 by papsphilip
spelling

[tamagochy]

You forget to multiply for inverted matrix.

 

orient planes_fix.hipnc

[papsphilip]

almost there, one problem i see is that the plane normals are not all facing the same way.

Also if i transform them at the origin can place them back at their original positions?

orient plane.hip

[tamagochy]

Yes normals can be in different directions, if you need one direction you can use normal vector in building matrix.

orient plane_fix.hipnc

[papsphilip]

4 hours ago, tamagochy said:

Yes normals can be in different directions, if you need one direction you can use normal vector in building matrix.

orient plane_fix.hipnc

thanks a lot for the help, this was really usefull!