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Transfer a bounding box pivot orientation to another object

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symbi
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Joined: Oct. 2021
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Hello,

i have a question maybe someone could help with.

I basically have an object already at a specific position in space, where its actual pivot lay at origin (0,0,0).

Using $CEX,$CEY,$CEZ is fine in a transform node to get the pivot to the middle of the object, but the pivot rotate is still using the default rotation values (thus not following the object local axis), i need to orient the pivot to match the "bounding box" of the object. And I'm not too sure how to achieve this, I just want the pivot of the object to match the object bounding box.

I hope this make sense

thanks for the help
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BabaJ
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Joined: Sept. 2015
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If I'm understanding you right...did you put $CEX, etc. in the pivot translate parameter?

If you did, the rotations will be based around the object center. Maybe post what you've done.
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paulbrownv
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Joined: July 2015
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Hi!

I have the same question. Using $CEX, etc does translate the pivot but you don't get the rotation of that object from that.
If we use a BOUND node, we can activate "Oriented Bounding Box" and you get exactly that, but then how can we use that operation for a pivot? It says you can export xform and radii as attributes, but how to access them? (if that's where the information we need is stored)

Can someone help figure this out?
I'm a Houdini beginner too ;-)

Thanks!
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cncverkstad
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Joined: Aug. 2017
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Rabbit 
int dotranslate = chi("dotranslate");
int dotrotate = chi("dotrotate");
int doscale = chi("doscale");
int uniformscale = chi("uniformscale");
vector min0,max0,min1,max1;
getbbox(0,min0,max0);
getbbox(1,min1,max1);
vector size0 = max0-min0;
vector center0 = (max0+min0)/2;
vector size1 = max1 -min1;
vector center1 = (max1+min1)/2;

matrix T = 1 ;
matrix R = 1 ;
matrix S = 1 ;

if ( dotranslate){
    vector t = center1 -center0;
    translate(T,t);
    }

if (dotrotate){
    float size0_array[]= set(size0);
    float size1_array[]= set(size1);
    
    int size0_argsort[]= argsort(size0_array);
    int size1_argsort[]= argsort(size1_array);
    vector newsize = size0;
    
    vector mr[];
    for(int i;i<3; i++){
        vector axis;
        axis[size1_argsort[i] ]=1;
        mr[size0_argsort[i] ]=axis;
        
        newsize[size0_argsort[i]]= size0[size0_argsort[i]];
        }

        
    size0 = newsize;
    //mr[2]= cross(mr[0],mr[1]);
    R = set(mr);

}
if(doscale){
    //@P = fit(@P,min0,max0,min1,max1);
    vector s = size1/size0;
    if (uniformscale){
        s = min(s);
        }
        scale(S,s);
}

vector p = center0;matrix X = 1;translate(X,p);

matrix xform = invert(X)*R*S*T*X;

string prim_type_name = primintrinsic(0,"typename",@primnum);
if(match('Packed*',prim_type_name)){
    matrix xform0 = getpackedtransform(0,@primnum);
    setpackedtransform(0,@primnum,xform0*xform);
    }else{
        @P *= xform;
    }

other 
node = hou.pwd()
geo = node.geometry()

obb = geo.orientedBoundingBox()
t = obb.center()
size = obb.sizevec()
rotation = obb.rotation().inverted()
r = rotation.extractRotates()

box = hou.sopNodeTypeCategory().nodeVerb('box')
box.setParms({'size':size,'r':r,'t':t});
geo1 = hou.Geometry()
box.execute(geo1,[])
geo.merge(geo1)

obb_min = t-size/2
obb_max = t+size/2
geo.addAttrib(hou.attribType.Global,'obb_min',hou.Vector3(),0,0)
geo.addAttrib(hou.attribType.Global,'obb_max',hou.Vector3(),0,0)
geo.addAttrib(hou.attribType.Global,'obb_rot',hou.Vector3(),0,0)
geo.setGlobalAttribValue('obb_min',obb_min)
geo.setGlobalAttribValue('obb_max',obb_min)
geo.setGlobalAttribValue('obb_rot',r)

with 2
int dotranslate = chi("dotranslate");
int dotrotate = chi("dotrotate");
int doscale = chi("doscale");
int uniformscale = chi("uniformscale");


vector min0 = detail(0,'obb_min');
vector max0 = detail(0,'obb_max');
vector rot0= radians(detail(0,'obb_rot'));

vector min1= detail(1,'obb_max');
vector max1 = detail(1,'obb_max');
vector rot1= radians(detail(1,'obb_rot'));

vector size0 = max0-min0;
vector center0 = (max0+min0)/2;
vector size1 = max1 -min1;
vector center1 = (max1+min1)/2;

matrix T = 1 ;
matrix R = 1 ;
matrix S = 1 ;

if ( dotranslate){
    vector t = center1 -center0;
    translate(T,t);
    }

if (dotrotate){
    float size0_array[]= set(size0);
    float size1_array[]= set(size1);
    
    int size0_argsort[]= argsort(size0_array);
    int size1_argsort[]= argsort(size1_array);
    vector newsize = size0;
    
    vector mr[];
    for(int i;i<3; i++){
        vector axis;
        axis[size1_argsort[i] ]=1;
        mr[size0_argsort[i] ]=axis;
        
        newsize[size0_argsort[i]]= size0[size0_argsort[i]];
        }

        
    size0 = newsize;
    //mr[2]= cross(mr[0],mr[1]);
    R = set(mr);

}
if(doscale){
    //@P = fit(@P,min0,max0,min1,max1);
    vector s = size1/size0;
    if (uniformscale){
        s = min(s);
        }
        scale(S,s);
}

vector p = center0;matrix X = 1;translate(X,p);

matrix R0 = 1;rotate(R0,rot0,0);
matrix R1 = 1;rotate(R1,rot1,0);

matrix xform = invert(X)*invert(R0)*R*S*R1*T*X;

string prim_type_name = primintrinsic(0,"typename",@primnum);
if(match('Packed*',prim_type_name)){
    matrix xform0 = getpackedtransform(0,@primnum);
    setpackedtransform(0,@primnum,xform0*xform);
    }else{
        @P *= xform;
    }
Edited by cncverkstad - Oct. 3, 2023 07:10:26

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