Softimage Blog

// query the geometry data
var obj = selection(0);
var geo = obj.Activeprimitive.Geometry;
var polygons = geo.Polygons;
 
// create an array to track which polygon has been visited
var polygonVisited = [];
var polygonsLeft = polygons.Count;
 
// fill up the array to say: "no polygon has been visited yet"
for(var i=0;i<polygons .count;i++)
{
	polygonVisited[i] = false;
}
 
// create some helper variables
var clusterIndices = [];
var currentRow = [];
 
// log the start of the process
logmessage("Starting with "+polygonsLeft+" polygons...");
 
// loop until there are no polygons left
// or there are still items in the cluster array
while(polygonsLeft > 0 || clusterIndices.length > 0)
{
	// if there are no items in the next row...
	if(currentRow.length == 0)
	{
		// if there are items in the cluster index array
		if(clusterIndices.length > 0)
		{
			// log the creation of the cluster
			logmessage("Creating cluster with "+clusterIndices.length+" elements...");
 
			// create a new mesh containing all of these polygons
			// first, create an array containing all pointindices
			// and two additional point hash arrays
			// of which one is used to determine if a point is already used
			// and the second one is used to map the original index to the new one
			var pointIndices = [];
			var pointUsed = [];
			var pointNewIndex = [];
 
			for(var i=0;i<clusterIndices.length;i++)
			{
				var poly = polygons.item(clusterIndices[i]);
				var pointIndexArray = poly.points.indexArray.toArray(); //(VBS to JScript conversion)
 
				// loop through all points and check if it they are used
				for(var j=0;j<pointIndexArray.length;j++)
				{
					var index = pointIndexArray[j];
					if(!pointUsed[index])
					{
						pointNewIndex[index] = pointIndices.length;
						pointIndices.push(index);
						pointUsed[index] = true;	
					}
				}
			}
 
			// now, create the array of the positions of all points of this island
			var islandPos = [];
			for(var i=0;i<pointIndices.length;i++)
			{
				var point = geo.points.item(pointIndices[i]);
				islandPos.push(point.position.x);
				islandPos.push(point.position.y);
				islandPos.push(point.position.z);
			}
 
			// now we need to create the description of the polygons
			var islandPoly = [];
			// for that we loop over the polygons of the island again
			// and record their pointindices, well, actually the remapped
			// indices (given by the pointNewIndex hash array)
			for(var i=0;i<clusterIndices.length;i++)
			{
				var poly = polygons.item(clusterIndices[i]);
				var pointIndexArray = poly.points.indexArray.toArray(); //(VBS to JScript conversion)
 
				// first add the number of points of this polygon 
				// to this polygon's description
				islandPoly.push(pointIndexArray.length);
 
				// now add the remapped index for each point to the description
				for(var j=0;j<pointIndexArray.length;j++)
				{
					var index = pointIndexArray[j];
					islandPoly.push(pointNewIndex[index]);
				}
			}
 
			obj.Parent.AddPolygonMesh(islandPos,islandPoly,obj.name+"_island");
			clusterIndices = [];
 
			// if there are no polyons left we can stop now
			if(polygonsLeft == 0)
				break;
		}
 
		// loop over the polygons and try to find 
		// one which hasn't been visited yet
		for(var i=0;i<polygons.Count;i++)
		{
			if(polygonVisited[i] == false)
			{
				currentRow.push(i);
				clusterIndices.push(i);
				polygonVisited[i] = true;
				polygonsLeft--;
				break;
			}
		}
	}
 
	// define the nextrow after the current row
	var nextRow = [];
 
	// loop over all items in the current row
	for(var i=0;i<currentRow.length;i++)
	{
		var polygon = polygons.item(currentRow[i]);
		var neighbors = polygon.NeighborPolygons();
 
		// loop through all of the neighbors and add them to the nextRow
		for(var j=0;j<neighbors.count;j++)
		{
			// check if the neighbor has been
			// visited yet
			var neighbor = neighbors.item(j).index;
			if(polygonVisited[neighbor]==false)
			{
				// add the neighbor to the next row
				nextRow.push(neighbor);
				clusterIndices.push(neighbor);
				polygonVisited[neighbor] = true;
				polygonsLeft--;
				break;
			}
		}
	}
 
	currentRow = nextRow;
}
 
selection.SetAsText(obj.name+"_island*");