I came across the same problem 2 weeks ago... Well I didn't find any
nice way of doing it but I wrote a
small scripted Event that stores in a UserDataBlob the coordinates at
which a particle is being emmited,
and than read the values and store it in the Goal_0_UVWI parameter for
the goal.
It gets slow with a lot of particle, but you could start from that
exemple and modify it to suit your need..
Hope this helps...
here is a small exemple scene of what I did.. just run it in a new scene
and you will see what it does.
//------------START-------------//
//Stick_Emission_01.js
//By Sebastien Nadeau
//Description:
//--------------
//USER PARAM
var nbParticle = 100000;
var poffset = 0.1;
//--------------
Main();
function Main()
{
//Create Sphere
var EmmiterGoal = CreatePrim("Sphere", "MeshSurface", null,
null);
ApplyTopoOp("TriangulatePolygons", EmmiterGoal, siUnspecified,
siPersistentOperation, null);
FreezeModeling(EmmiterGoal, null, null);
//Create WeigthMap
var WeightMap = CreateWM(EmmiterGoal);
//Create Particle
var Cloud = CreateParticleCloud(EmmiterGoal, "")(0);
//Find Ptype and Emission
var CloudOp =
Cloud.ActivePrimitive.NestedObjects("ParticlesOp");
for ( var i=0; i<CloudOp.InputPorts.Count; i++ ){
if(CloudOp.InputPorts(i).Target2.type == "ParType")
var pType = CloudOp.InputPorts(i).Target2;
if(CloudOp.InputPorts(i).Target2.type == "EmissionProp")
var EmissionProp= CloudOp.InputPorts(i).Target2;
}
//Setup Goal
var Goal = AddParticleGoal(pType , EmmiterGoal, null)(1)(0);
//Stick
Goal.Parameters("Behavior").Value = 4;
//Set Emission
EmissionProp.Parameters("Rate").value = nbParticle;
ApplyOp("MapCompOp2",
WeightMap+";"+EmissionProp.Parameters("Rate"), null, null, null, 0);
//Set Other Param
pType.Parameters("LiveForever").Value = true;
pType.Parameters("AlignOnVelocity").Value = true;
//Event
var PEvent = AddParticleEvent(pType, "", null)(0)(0);
PEvent.Parameters("EventTrigger").Value = 2;
PEvent.Parameters("TriggerValue").Value = 1;
PEvent.Parameters("EventAction").Value = 6;
PEvent.Parameters("ScriptLanguage").Value = 1;
PEvent.Parameters("ScriptContext").Value = 2;
//Offset Emission Animation
var oPlayCrtl = Dictionary.GetObject( "PlayControl" );
SetKey(EmissionProp.Parameters("Mute"),
oPlayCrtl.Parameters("Out").value - 1, false, null);
SetKey(EmissionProp.Parameters("Mute"),
oPlayCrtl.Parameters("Out").value, true, null);
SetKey(PEvent.Parameters("Mute"),
oPlayCrtl.Parameters("Out").value - 1, false, null);
SetKey(PEvent.Parameters("Mute"),
oPlayCrtl.Parameters("Out").value, true, null);
//Offset Particle Simulation
CloudOp.Parameters("Offset").Value =
oPlayCrtl.Parameters("Out").value - 1;
//Create UserDataBlob Properties to save Arrays
Cloud.AddProperty( "UserDataBlob", false, "Distribution" );
//Set Temp Event Script to store the Goal values in the
UserDataBlob
PEvent.Parameters("Script").Value = "var aDistrib = new
Array();\r\n\r\nfor ( var i=0; i<inParticleCloud.Particles.Count; i++
)\r\n {\r\n\tvar inParticle = inParticleCloud.Particles(i);\r\n\r\n//Get
UVWI\r\n\tvar q =
inParticle.Attributes(\"Goal_0_UVWI\").Value;\r\n\r\n//Particle
position\r\n\tvar v2 = XSIMath.CreateVector3();\r\n\tv2 =
inParticle.Position;\r\n\r\n//Point Locator\r\n\tvar EmitGeo =
Dictionary.GetObject(\""+EmmiterGoal.FullName+"\").ActivePrimitive.Geome
try;\r\n\tvar ClosestPointLocator =
EmitGeo.GetClosestLocations(VBArray(v2.Get2()).toArray());\r\n\r\n//Get
Triangle and Coordinate\r\n\tvar Poly =
EmitGeo.GetPolygonIndexArray(ClosestPointLocator).toArray();\r\n\tvar
BaryCoords =
EmitGeo.GetTriangleWeightArray(ClosestPointLocator).toArray();\r\n\tq.Se
t (Poly[0], BaryCoords[0], BaryCoords[2] , q(3))\r\n\r\n//Get Closest
point to Mesh\r\n\tvar v1 = XSIMath.CreateVector3();\r\n\tvar Cp =
EmitGeo.EvaluatePositions(ClosestPointLocator).toArray();\r\n\tv1.Set(
Cp[0], Cp[1], Cp[2]);\r\n\t\r\n//Get
Orientation\r\n\tv2.SubInPlace(v1);\r\n\tv2.NormalizeInPlace();\r\n\tv2.
ScaleInPlace("+poffset+");\r\n\r\n//Set the
offset\r\n\tinParticle.Attributes(\"Goal_0_Offset\").Value =
v2;\r\n\t\r\n//Set new
Index\r\n\tinParticle.Attributes(\"Goal_0_UVWI\").Value =
q;\r\n\t\t\r\n//Set UserDataBlob\r\n\taDistrib.push(v2.X, v2.Y,
v2.Z);\r\n\taDistrib.push(q.W, q.X, q.Y,
q.Z);\r\n}\r\nDictionary.GetObject(\""+Cloud.FullName+"\").Properties(\"
Distribution\").Value = aDistrib;";
//Go to Last Frame
LastFrame();
refresh();
//-----------------COMMENT THE REST TO STUDY THE FIRST PART OF THE
SCRIPT---------------------------//
//Set Event Script that will read the UserDataBlob at the first
frame
PEvent.Parameters("Script").Value = "var aDistrib =
Dictionary.GetObject(\""+Cloud.FullName+"\").Properties(\"Distribution\"
).Value.split(\",\");\r\n\r\nfor ( var i=0; i <
(inParticleCloud.Particles.Count * 7); i += 7 )\r\n{\r\n\tvar inParticle
= inParticleCloud.Particles(i/7);\r\n//Set the offset\r\n\tvar v1 =
XSIMath.CreateVector3();\r\n\tv1.Set(aDistrib[i], aDistrib[i+1],
aDistrib[i+2]);\r\n\tinParticle.Attributes(\"Goal_0_Offset\").Value =
v1;\r\n\r\n//Set new Index\r\n\tvar q =
XSIMath.CreateQuaternion();\r\n\tq.Set(aDistrib[i+3], aDistrib[i+4],
aDistrib[i+5],
aDistrib[i+6]);\r\n\tinParticle.Attributes(\"Goal_0_UVWI\").Value
=q;\r\n\r\n}";
//Reset Offset
CloudOp.Parameters("Offset").Value =
oPlayCrtl.Parameters("In").value;
//Animate Emission
RemoveAnimation(EmissionProp.Parameters("Mute"), 0,
null);
RemoveAnimation(PEvent.Parameters("Mute"), 0, null);
SetKey(EmissionProp.Parameters("Mute"),
oPlayCrtl.Parameters("In").value, false, null);
SetKey(EmissionProp.Parameters("Mute"),
oPlayCrtl.Parameters("In").value + 1, true, null);
SetKey(PEvent.Parameters("Mute"),
oPlayCrtl.Parameters("In").value, false, null);
SetKey(PEvent.Parameters("Mute"),
oPlayCrtl.Parameters("In").value + 1, true, null);
//Go Back to First Frame
FirstFrame();
//-----------------------------------------------//
}
function CreateWM(oObj)
{
var WM = CreateWeightMap(null, oObj, "Weight_Map", null,
null)(0);
var Weights = VBArray(WM.Elements.Array).toArray();
var Points = oObj.ActivePrimitive.Geometry.Points;
var p1 = oObj.ActivePrimitive.Geometry.Points(0).Position;
var vdist = XSIMath.CreateVector3();
var maxDist = 0;
for(var j = 0; j < Points.Count;j++)
{
vdist.Sub(p1, Points(j).Position);
Weights[j] = vdist.Length();
if(Math.random() < 0.8)
Weights[j] = 0;
if(Weights[j] > maxDist)
maxDist = Weights[j];
}
for(var k = 0; k < Points.Count; k++)
Weights[k] = (Weights[k] / maxDist);
WM.Elements.Array = Weights;
return WM;
}
//------------END-------------//
-----Original Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On Behalf
Of Kris Rivel
Sent: Monday, April 24, 2006 6:25 PM
To: XSI List Server
Subject: stick based goal with weight map
Is there a way to have particles stick to a weight map or texture map?
I need to generate some particles that are on a mesh as the mesh moves
around. The "stick" goal simply overrides any weight map you emit from
resulting in the particles being evenly scattered on the surface.
Kris
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