Time to summon the Wiki fairy...
> Here is a more in-depth JScript of how to play with hair... it's a JScript
> so you will need to convert it to Python but it shows a lot of examples of
> how to access different elements and how to find the right connected point
> from the emmitting geometry. I hope it can help out and if you have anymore
> questions, let us know! I'm assuming in this script you have allready
> created a hair object and it is named "hair" and that it has at least 4
> guide hairs...
>
>
>
>
> //Get hair object
> var oHair = Dictionary.GetObject( "Hair", false );
>
> //Get hair points
> var oPoints = oHair.Activeprimitive.Geometry.Points;
>
> //get count and position array
> var nb_HairPts = oPoints.count;
> var nb_HairGuides = nb_HairPts/14;
> var oPointsPositionArray = oPoints.PositionArray.toArray();
>
> //To get global transform for point positions
> var oMatrix = XSIMath.CreateMatrix4();
> var oPt = XSIMath.CreateVector3();
> oHair.Kinematics.Global.Transform.GetMatrix4(oMatrix);
>
> //log position information
> for ( var i=0; i<oPointsPositionArray.length; i+=3 ) {
> var no_hair = parseInt(oPoints(i/3).index/14); //the same as
> "parseInt((i/3)/14)" or "parseInt(i/42)"
> var guidePtNb = oPoints(i/3).index%14;
> LogMessage(oHair.fullname+".pnt[("+no_hair+","+guidePtNb+")] has local
> position of ("
> +oPointsPositionArray[i]+","+oPointsPositionArray[i+1]+","+oPointsPositio
> nArray[i+2]+")");
>
> oPt.Set(oPointsPositionArray[i], oPointsPositionArray[i+1],
> oPointsPositionArray[i+2]);
> oPt.MulByMatrix4InPlace(oMatrix);
> LogMessage(oHair.fullname+".pnt[("+no_hair+","+guidePtNb+")] has global
> position of ("
> +oPt.x+","+oPt.y+","+oPt.z+")");
> }
>
> //select a hair point
> SelectGeometryComponents("Hair.pnt[(3,13)]");
> var oPtSel = Selection(0);
> var oPtColl = oPtSel.SubComponent.ComponentCollection;
>
> logmessage("number of hair points: "+nb_HairPts);
> logmessage("number of guide hairs: "+nb_HairGuides);
> logmessage("number of selected points: "+oPtColl.count);
> logmessage("index of first point selected: "+oPtColl(0).index);
>
> //reselects the same point... just for demonstration reasons
> SelectGeometryComponents(oHair.fullname+".pnt["+oPtColl(0).index+"]");
>
> var no_hair = parseInt(oPtColl(0).index/14); //get the guide hair number
> var guidePtNb = oPtColl(0).index%14; //get the point along the guide hair
> strand (0 = root (not geometry but hair root), 13 = hair tip)
> SelectGeometryComponents(oHair.fullname+".pnt[("+no_hair+","+guidePtNb+")]")
> ; //yet another way to select
>
>
> //to find the connected point from the hair root to the geometry, we need to
> find the cluster if it exist:
> var oConstructionHistory = oHair.Activeprimitive.ConstructionHistory;
> var oHairGenOp;
> oEnum = new Enumerator( oConstructionHistory );
> for (;!oEnum.atEnd();oEnum.moveNext())
> {
> // Print the name of the operator
> if (oEnum.item().name == "Hair Generator Operator") {
> oHairGenOp = oEnum.item();
> break;
> }
> }
> var oCluster = FindCluster(oHairGenOp);
> if (oCluster) {
> LogMessage("Hair is applied on a cluster!!");
>
> //create a index table array that maps the hair guide index to the parent
> polymest point index
> var IdxMap = MapIdx_PolyCls_To_HairVtxCls(oCluster,
> oHair.parent.ActivePrimitive.Geometry);
>
> //selects the polymesh point index connected to hair guide point (3,13)
> SelectGeometryComponents(oHair.parent.fullname+".pnt["+IdxMap[no_hair]+"]")
> ;
>
> //or get the point directly in object model
> var oPt = oHair.parent.ActivePrimitive.Geometry.Points(IdxMap[no_hair]);
> }
> else {
> LogMessage("Hair is applied directly on object!!");
>
> //no cluster, the polymesh point indices are the same as the guide hair
> indices
> SelectGeometryComponents(oHair.parent.fullname+".pnt["+no_hair+"]");
> var oPt = oHair.parent.ActivePrimitive.Geometry.Points(no_hair);
> }
>
>
> function FindCluster(op)
> {
> // for each port group
> for ( var idxGroup = 0; idxGroup < op.GetNumPortGroups(); idxGroup++ )
> {
> // for each instance in a port group
> for ( var idxInstance = 0; idxInstance < op.GetNumInstancesInGroup(
> idxGroup ); idxInstance++ )
> {
> // for each port in a port group instance
> for ( var idxPort = 0; idxPort < op.GetNumPortsInGroup( idxGroup );
> idxPort++ )
> {
> // get a specific port
> var port = op.PortAt( idxPort, idxGroup, idxInstance );
> var target = port.target2;
> if (target != null){
> if (target.type == "poly")
> {
> //poly cluster found...
> return target;
> }
> }
>
> }
> }
> }
> //no poly cluster found...
> return null;
> }
>
>
> function MapIdx_PolyCls_To_HairVtxCls(polyCls, mesh)
> {
> var polysIdx = polyCls.Elements.Array.toArray();
> var polys = mesh.Polygons;
> var nbPolys = polysIdx.length;
> var nbVertices = mesh.points.count;
> var taken = new Array();
> for (var i=0; i<nbVertices; i++) taken[i] = false;
> var indices = new Array();
> for (i=0; i<nbPolys; i++){
> var face = polys(polysIdx[i]);
> var neighs = face.Points;
> var nbNeighs = neighs.count;
> for (var j=0; j<nbNeighs; j++){
> var idx = neighs(j).index;
> if (!taken[idx]){
> taken[idx] = true;
> indices.push( idx );
> }
> }
> }
> return indices;
> }
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf
> Of kim aldis
> Sent: Thursday, May 25, 2006 2:46 AM
> To: XSI(at)Softimage.COM
> Subject: RE: [scripting] hair geometry
>
>
> You can access hair point data in the same way as you do point data on a
> poly mesh.
>
> var aPoints =
> oObj.Activeprimitive.Geometry.Points.PositionArray.toArray();
>
> for ( var i=0; i<aPoints.length; i+=3 ) {
> }
>
> The number of strands is the count of points divided by 14. It's the only
> way to get the strand count.
>
> The root point of a hair strand doesn't exist in the hair point data, you
> have to retrieve it from the emitting geometry by looping through face nodes
> in a unique way:-
>
> Istrand = 0;
>
> For each face
> for each node on face
> if ( ! (point is visited) )
> iStrand ++
>
>
> Kind of thing. I usually push the point position onto an array so I can
> index it directly.
>
> > -----Original Message-----
> > From: owner-xsi(at)Softimage.COM
> > [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Greg Smith
> > Sent: 24-May-2006 23:30
> > To: XSI_MailingList
> > Subject: [scripting] hair geometry
> >
> > Okay so I cracked my knuckles, and started to get into the
> > nuts and bolts of the hair geometry primitive and so far I am
> > a little frustrated. Maybe its because I am still a little
> > wet behind the ears when tinkering with the internals of xsi,
> > I don't know.
> >
> > So down to the nitty gritty. Using python, I am trying to get
> > access at components of hair geometry object. one of the
> > things I am having an issue with is finding a direct method
> > in finding the total amount of guide hairs live on the hair
> > object. Thus far I haven't found a direct method. The only
> > thing I have come up with so far is dividing the total number
> > of points found in the hair object by the total amount of
> > points found in a guid hair. This gives me the appropriate
> > number, but I would prefer something a little more elegent.
> >
> > Is there any way to grab the 2d array index of a point using
> > the object model?
> > when I select a point on one of the guide hairs, I get this
> > line in the history log.
> >
> > Application.SelectGeometryComponents("Hair.pnt[(27,3)]")
> >
> > However I don't want to use a string argument, I'd much
> > rather use an object method, however when I try, I can't
> > figure out how to access a point component in that method. I
> > can gain access of a point by index number from the
> > pointcollection using the code below.
> >
> > xsi = Application
> > hr = xsi.ActiveSceneRoot.FindChild('Hair')
> > ohair = hr.ActivePrimitive.Geometry
> > oPnts = ohair.Points
> >
> > I tried appending .SubComponent to oPnts and work from there,
> > but I can't figure out where I am supposed to proceed.
> >
> > any Ideas?
> >
> > Thanks,
> >
> > Greg
> >
> >
> >
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> >
> >
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