reading from arbitrary geo in a shader

[meeotch]

Is it possible to access an arbitrary piece of geo (i.e., not the one being shaded) from a shader?  I know that you can read data from pointclouds on disk.  I also read somewhere that the "op:" syntax doesn't work for shaders (although it does work for referencing COPs from a shader, yes?).  Presumably, you'd have to alert houdini somehow to the fact that there was non-rendered geo that needed to be pushed to the ifd.

The context is that I'm trying to write a shader that does coloring based on distance from a set of guide curves.  The color transitions need to be sharp, not blurry, therefore baking the colors into the shaded surface's points in SOPs isn't an option, unless I dice it up into a zillion polys.  (I suppose a fallback plan would be cooking the color info down into a very large texture.  But all of this is animated, so I'd prefer not to render a few hundred frames of textures.)

I can confirm that using the xyzdistance VOP from within the shader doesn't seem to work - neither with op: syntax, nor reading the curves from a file on disk.

[dchow1992]

check to see if you forgot to transform P to object/world space before xyzdist

[meeotch]

D'oh!  Dude - nice one.  You're like a psychic for boneheaded mistakes. Reading the curve geo from a file seems to work, with that fix.

op: syntax still doesn't work, which is not entirely surprising.  Anyone know if that's is something that's been implemented, and maybe it's another "PEBKAC" issue?