I stumbled on the 'rivet script' when I was looking for a solution to movement for snake scales. I need to constain a rigid object (the scales) at a consistent point to a deforming one. The script has been working great, but now further into the td process I have some other aspects that I need to resolve. I need an additional constraint direction besides the vertex normal vector obtained from the parent polygon to dictate how the child moves. The plan is to try and modify the script so that the secondary direction follows the edge flow towards the front end of the object. I am hoping I can take this vector direction easily from the edge itself, but I have a feeling it might not be that simple. I have some limited experience doing this sort of constraint based relationship using dot products and cross products in houdini, but in Maya its a bit more challenging for me. I am confident that I do only need one more direction though. Any suggestions on how to resolve this? I have attached several images on a low poly test object to give you a better idea. The first shows the curve at rest in rest position, while the two second images show how the secondary curve deviates from the ideal vector position along the 'snakes' body surface.
Here is the link to the script https://www.creativecrash.com/maya/script/rivet-button/description#tabs
Along with a link to the reference picture https://drive.google.com/file/d/0B1O6s3CJ1wwlN1lOS1E1ZXVuOVk/view?usp=sharing
And here is the script,
// Copyright (C) 2000-2001 Michael Bazhutkin - Copyright (C) 2000 studio Klassika
// www.geocites.com/bazhutkin
// bazhutkin@mail.ru
//
// Rivet (button) 1.0
// Script File
// MODIFY THIS AT YOUR OWN RISK
//
// Creation Date: April 13, 2001
//
//
// Description:
// Use "Rivet" to constrain locator to polygon or NURBS surfaces
// Select two edges on polygon object
// or select one point on NURBS surface and call rivet
// Parent your rivets and buttons to this locator
global proc string rivet ( )
{
string $nameObject;
string $namePOSI;
string $parts[];
string $list[] = `filterExpand -sm 32`;
int $size = size($list);
if ($size > 0)
{
if ($size != 2)
{ error("No two edges selected");
return "";
}
tokenize($list[0],".",$parts);
$nameObject = $parts[0];
tokenize($list[0],"[]",$parts);
float $e1 = $parts[1];
tokenize($list[1],"[]",$parts);
float $e2 = $parts[1];
string $nameCFME1 = `createNode curveFromMeshEdge -n "rivetCurveFromMeshEdge1"`;
setAttr ".ihi" 1;
setAttr ".ei[0]" $e1;
string $nameCFME2 = `createNode curveFromMeshEdge -n "rivetCurveFromMeshEdge2"`;
setAttr ".ihi" 1;
setAttr ".ei[0]" $e2;
string $nameLoft = `createNode loft -n "rivetLoft1"`;
setAttr -s 2 ".ic";
setAttr ".u" yes;
setAttr ".rsn" yes;
$namePOSI = `createNode pointOnSurfaceInfo -n "rivetPointOnSurfaceInfo1"`;
setAttr ".turnOnPercentage" 1;
setAttr ".parameterU" 0.5;
setAttr ".parameterV" 0.5;
connectAttr -f ($nameLoft + ".os") ($namePOSI + ".is");
connectAttr ($nameCFME1 + ".oc") ($nameLoft + ".ic[0]");
connectAttr ($nameCFME2 + ".oc") ($nameLoft + ".ic[1]");
connectAttr ($nameObject + ".w") ($nameCFME1 + ".im");
connectAttr ($nameObject + ".w") ($nameCFME2 + ".im");
}
else
{ $list = `filterExpand -sm 41`;
$size = size($list);
if ($size > 0)
{
if ($size != 1)
{ error("No one point selected");
return "";
}
tokenize($list[0],".",$parts);
$nameObject = $parts[0];
tokenize($list[0],"[]",$parts);
float $u = $parts[1];
float $v = $parts[2];
$namePOSI = `createNode pointOnSurfaceInfo -n "rivetPointOnSurfaceInfo1"`;
setAttr ".turnOnPercentage" 0;
setAttr ".parameterU" $u;
setAttr ".parameterV" $v;
connectAttr -f ($nameObject + ".ws") ($namePOSI + ".is");
}
else
{ error("No edges or point selected");
return "";
}
}
string $nameLocator = `createNode transform -n "rivet1"`;
createNode locator -n ($nameLocator + "Shape") -p $nameLocator;
string $nameAC = `createNode aimConstraint -p $nameLocator -n ($nameLocator + "_rivetAimConstraint1")`;
setAttr ".tg[0].tw" 1;
setAttr ".a" -type "double3" 0 1 0;
setAttr ".u" -type "double3" 0 0 1;
setAttr -k off ".v";
setAttr -k off ".tx";
setAttr -k off ".ty";
setAttr -k off ".tz";
setAttr -k off ".rx";
setAttr -k off ".ry";
setAttr -k off ".rz";
setAttr -k off ".sx";
setAttr -k off ".sy";
setAttr -k off ".sz";
connectAttr ($namePOSI + ".position") ($nameLocator + ".translate");
connectAttr ($namePOSI + ".n") ($nameAC + ".tg[0].tt");
connectAttr ($namePOSI + ".tv") ($nameAC + ".wu");
connectAttr ($nameAC + ".crx") ($nameLocator + ".rx");
connectAttr ($nameAC + ".cry") ($nameLocator + ".ry");
connectAttr ($nameAC + ".crz") ($nameLocator + ".rz");
select -r $nameLocator;
return ($nameLocator);
}
rivet;
