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Showing results for tags 'vex expression'.
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Hi, I am trying to apply pop wind force to only non-isolated points in flip sim. Basically I don't want to apply this force to droplets. My VEX expression is like this but it doesn't seem to be working. Am I missing something or doing completely wrong? Thanks.
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I have some prims that I need to drive through a Clip SOP. Each prim has got its own clipping plane origin and direction, previously computed and stored in prim vector attributes, eg v@clipOrigin and v@clipDirection I would like to connect these attribute values to the inputs of a Clip SOP: Origin & Direction parameters but cannot figure out how to do it. I tried (just showing the Origin.x parameter of the Clip here, but the y/z and the Direction.x/y/z would be analogous: @clipOrigin.x no error, but wrong result (alway zero) v@clipOrigin.x error: unable to evaluate expression - extra tokens detected in expression ch("../nodeJustAboveClip/clipOrigin/x") error (bad parameter reference) hou.ch("../nodeJustAboveClip/clipOrigin/x") error (unknown function in expression) also tried with a spare parameter I realize the clipOrigin is not a parameter on my nodeJustAboveClip SOP, but rather an attribute on its prim output. So 3-5 are likely just plain wrong. Just in case Clip assumes it is running over points rather than prims, I also inserted a Attribute Promote SOP to copy the prim v@clipOrigin to each point. With version 1 above, the result is the same - no error but always zero. If you know how to do this, thank you in advance ! This is in Houdini 16.5 Indie -------- SOLVED: I was using the wrong syntax in the parameter expressions. You can pick up prim or detail attributes in SOP (not just Clip SOP) parameters like this: prim(surface_node, prim_num, attrib_name, attrib_index) detail(surface_node, attrib_name, attrib_index) details(surface_node, attribute) point(surface_node, point_number, attribute, index) Note these are VEX expression functions used in parameter expression one-liners, not regular VEX functions used in wrangles. The signatures of the functions are slightly different.
