Measure

if (primvertexcount(0, @primnum) > 4) - test by by n-gons Find N-gones /// UZUPEŁNIC

Distance

distance() - Distence between 2 points
surfacedist() - Distance of a point to a group of points along the surface of a geometry

Distance From Geometry SOP

@dist = distance({0,0,0},@P); -
@mask = 1-clamp(pow(distance(@P*{1,0,1},{0,0,0}),ch("pow"))*ch("multi"),0,1); -

Spherical Mask between points

vector p1 = point(1,'P',0);
vector p2 = point(1,'P',1);

float r = distance(p1,p2);
@Cd = (r-distance(@P, p1))/r;

Linear Gradient

vector p1, p2, v1, v2;
p1 = point(1,'P',0);
p2 = point(1,'P',1);

v1 = @P-p1; // treat p1 as origin;
v2 = normalize(p2-p1);

float r = distance(p1,p2);
@Cd = dot(v1,v2)/r;

XYZ Dist

Hou doc xyzdist()
Hou doc PrimUV - need to know the nearest @primnum and uv
primuv() - interpolated value of an attribute over the parametric surface of the primitive primuv(2, "P", posprim, primuv)

Fix points on a moving object
Input0: the scattered points in a static position (init frame)
Input1: geometry at rest position
Input2:- moving object

int posprim;
vector primuv;
float maxdist = 10;
float dist = xyzdist(1, @P, posprim, primuv, maxdist);
vector pos = primuv(2, "P", posprim, primuv);
@P = pos;

Nearpoint(s)

Use spatial proximity (closest point in a geometry) nearpoint() -
nearpoints() -

i@nearpt = nearpoints(0, @P, 1e34, 2)[1:][0]; - All the closest point in a geometry (not self)

int pts[] = {1,2,3,4};

Neighbour(s)

Return connected points (that share an edge with a given point)
Group Expand SOP - Attribute is spread to its connected neighbors

neighbour() -
neighbours() -
polyneighbours() - same for shared edge in prims

Return @ptnum or array of @ptnums of the next point connected to a given point

` …. neighbour()-i[]@pts = neighbours(0, @ptnum);` - Array of Connected Points @ptnum’s

Neighbourcount

neighbourcount() - How Many points connected

i@count = neighbourcount(0,@ptnum); - How Many Edges from point
if (neighbourcount(0,@ptnum)<3) removepoint(0, @ptnum); - Delete inline points with only 2 edges

ptlined

Distance to line (defined by 2 points)

f@dist_to_line = ptlined({0,0,0}, {0,1,0}, @P);

MinPos

minpos() - stuff to “stick” stuff to an object. Closest position on the surface of a geometry
position of the closest point on the target geo

Closest point on geo to line (RunOver:Prims)
Input0: point or spline
Input1: geometry or spline to find closest point

int pts[] = primpoints(0,@primnum);
int count = len(pts);
float mindist = 999999;
vector currminpos = {0,0,0};

for(int i=0;i<count;i++){
    vector minpos = minpos(1,point(0,"P",pts[i]));
    float dist = distance(minpos,point(0,"P",pts[i]));
    if(dist < mindist){
        mindist = dist;
        currminpos = minpos;
    }
}

addpoint(0, currminpos);
setpointgroup(0, "closest", count, 1, "set" );

Find Shortest Path

Bounding Box

v@Cd = relbbox(0, @P); - relative position of point in relation to bbox.
v@bbox_size = getbbox_size(0); - Bound size
v@centroid = getbbox_center(0); - Relative Bbox
v@bbox_min = getbbox_min(0); - get world min of geometry bounds
v@bbox_max = getbbox_max(0); - get world max of geometry bounds
getbbox(0,vector min,vector max); - get both min and max

vector min, max;
getbbox(0,min, max);
vector center = (min+max)/2;

voxelpixel.xyz blog: dist and neighbors

Point Clouds

!video

Point Clouds architecture in VEX is based on data structure called kd-trees. They are created in memory from Houdini geometry and kept in cache for a period of VEX execution. Handle is like a reference of this structure inside a single VEX instance . If you create two point clouds, they will probably have handles 0 and 1 pc functions require that handle to find the point cloud to both read and write in to the separate memory. It’s basically an integer which lets you tell to other pc* functions which point cloud you’re interested in (among many possibly created)

pcopen() - the points are ordered from closest to farthest. (Returns a handle to a point cloud file)
pcclose(handle) Na koniec zamykamy uchwyt, aby uzyskać dostęp do bazy danych punktu
pcfilter() - Filters points found by pcopen using a simple reconstruction filter
pcfind - [] List of closest points (nearpoints) pcfind(1,'P',@P,ch('d'),25);
pcfind_radius(1,"P","pscale", 1.0, @P, maxdist, maxpts); - [] List of closest points taking into account their radius
pcfarthest() Returns the distance to the farthest point found in the search performed by pcopen.

Nearest point distance

int handle = pcopen(0,"P",v@P, 111,2);
float dist = pcimportbyidxf(handle,'point.distance',1);
@dist_neartst = dist;
@pscale =  dist;

Blur Attributes

int pc = pcopen(0, "P", @P, ch("rad"), chi("num"));
v@Cd = pcfilter( pc, "Cd");

Points Density

int handle = pcopen(0, "P", @P, ch("rad"), chi("num"));
int count = pcnumfound(handle);
f@density = float(count)/float(chi("num"));

Points Density

int pc[] = pcfind(0,'P',@P,ch('maxdist'),ch('maxpt'));
@Cd = float(len(pc))/ch('maxpt');

Transfer Attributes

int handle = pcopen(1,"P", @P, ch("rad"), chi("num"));
@`chs("attribute")` =  pcfilter(handle,chs("attribute"));

Iterate

int handle = pcopen(0,"P", @P, ch('rad'), 2);
vector close_pt;
while(pciterate(handle)){
    pcimport(handle, "P", close_pt);
    @N = close_pt - @P;
}

Remove overlaped prims

int prim_points[] = primpoints( geoself(), @primnum );
vector pos_accum = 0;

for ( int i = 0; i < len(prim_points); i++ )
{
    pos_accum += attrib( 0, "point", "P", prim_points[i] );
}

pos_accum /= len(prim_points);

int xyz_prim;
vector xyz_uv;

float xyz_dist = xyzdist( 0, pos_accum, xyz_prim, xyz_uv);

if ( xyz_prim > @primnum && xyz_dist < 0.001 )
    removeprim(0, @primnum, 1);
else if ( xyz_prim < @primnum && xyz_dist < 0.001 )
    removeprim(0, xyz_prim, 1);

delete points

if(@myAttribute > 0) removeprim(geoself(), @primnum, 1); // if you want to delete points owned by primitive itself or

if(@myAttribute > 0) removeprim(geoself(), @primnum, 0);