Fill Quads
ICE compound, emits particles evenly from each polygon, trying to keep the same particle size, also trying to fill polygon area as much possible. Number of rows and columns in one polygon, is determined by desired global count per mesh. In case of all rectangles, it should be able to do 1:1 covering. I made a prototype a while ago, for purpose of hair emitter - but emitting from triangles was a more robust solution for hair system.
Requirements:
1: polygon mesh, created only of quads (for triangles or five or more sides, it does something unwanted)
2: nice, unfolded UV projection on mesh - this is used for orientation. Let's say, "unique UV" in SI should be fine
3: ICE node on emitter mesh, with "initialize polymesh emitter" node - same as one from Kristinka Hair
Limitations:
1: it works properly only with quads
2: "polygons" in UV projection should be convex - usually they are with mentioned "unique UV", unfold, or like.
3: for now, in order to find vector for orientation, it interpolates between two sides of polygon. Taking a vector from possible tangent map, could do a nicer alignment.
Get the entire setup
here.
I've added a few additional options, possible this node could be used for procedurally animated "self - building" structures. There's "compensate pivot" which moves center of rotation to the side of particle. There's also "delete interior" for look of rivets on hull... "Max x Max" forces equal count for each polygon. X and Y moving is relative, 1 is distance to neighboring particle. "Smooth normal", if activated, calls interpolated point normal, off is non-interpolated surface geometric normal - second should be better for walls, buildings or like.
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Thanks guys for that. keep on dumping! (I mean fighting of course 
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