Does anyone know why the expression function xyzdist has a return_type argument that allows you to query UV values while the VEX equivalent does not?

I'm trying to loop through a collection of points scattered in space and get the interpolated UV value of the nearest spot on a mesh.

Thanks,
Kevin

Common for VEX functions is to have multiply signatures (while in hscript this doesn't work):
http://www.sidefx.com/docs/houdini12.5/vex/functions/xyzdist [sidefx.com]

Hey, thanks for the reply.

I get that VEX functions can be overloaded, but there's no version with a return_type argument, so I can't get back UV values like I can with the expression function. Why the difference?

I have a random point in space and I want to get the closest UV value from a nearby mesh. Any idea how to do that?

You could ray SOP the point onto the geometry and attribute transfer the uv…
It can also be done in VOPs and probably faster.

Cheers

KMcNamara
Hey, thanks for the reply.

I get that VEX functions can be overloaded, but there's no version with a return_type argument.

Second signature returns uvs and prim number in arguments (VEX's arguments are by reference in general):

float xyzdist(string geometry, vector pt, int &prim, vector &uv)

so (untested):


vector hitUV = 0;
int hitPrim = -1;
float dist = xyzdist(geometry, P, hitPrim, hitUV);

to get the distance, hit primitive number, and hit uv…

Ah, thanks guys. Got it working with both VOPSOP and Point Wrangle. My main problem was that my mesh was storing its UVs in barycentric coordinates, so I had to convert these to the actual UV space.

For example, my point wrangle code:

vector primUV = 0;
int hitPrim = -1;
xyzdist(@OpInput2, @P, hitPrim, primUV);

vector finalUV = 0;
prim_attribute(@OpInput2, finalUV, “uv”, hitPrim, primUV, primUV);

@uv = set(finalUV);