diff --git a/src/experimental/tiles_wfc.scad b/src/experimental/tiles_wfc.scad
index e1479606..5980d223 100644
--- a/src/experimental/tiles_wfc.scad
+++ b/src/experimental/tiles_wfc.scad
@@ -1,5 +1,7 @@
 use <util/flat.scad>;
 use <util/has.scad>;
+use <util/sum.scad>;
+use <util/rand.scad>;
 use <util/slice.scad>;
 use <util/every.scad>;
 use <util/map/hashmap.scad>;
@@ -91,16 +93,71 @@ function wf_remove(wf, x, y, removedStates) =
 		)
 	];
 
+function wf_collapse(wf, x, y) =
+    let(
+		weights = wf_weights(wf),
+		states_xy = wf_eigenstates_at(wf, x, y),
+		weights_xy = hashmap([
+		for(state = hashmap_keys(weights))
+			if(has(states_xy, state))
+				[state, hashmap_get(weights, state)]
+	    ]),
+		totalWeights = sum(hashmap_values(weights_xy)),
+		threshold = rand() * totalWeights,
+		states_weights = hashmap_entries(weights_xy)
+	)		
+	_wf_collapse(wf, x, y, states_weights, len(states_weights), threshold);
+
+function _wf_collapse(wf, x, y, states_weights, leng, threshold, i = 0) =
+    i == leng ? wf : 
+	let(
+		state = states_weights[i][0],
+		weight = states_weights[i][1],
+		t = threshold - weight
+	)
+	t < 0 ? _oneStateAt(wf, x, y, state) :  _wf_collapse(wf, x, y, states_weights, leng, t, i + 1);
+
+function _oneStateAt(wf, x, y, state) = 
+    let(
+	    eigenstates = wf_eigenstates(wf),
+		rowsBeforeY = slice(eigenstates, 0, y),
+		rowY = eigenstates[y],
+		rowsAfterY = slice(eigenstates, y + 1),	
+		statesBeforeX = slice(rowY, 0, x),
+		states = [state],
+		statesAfterX = slice(rowY, x + 1),	
+		newRowY = concat(
+		    statesBeforeX,
+		    [[state]],
+			statesAfterX
+		)		
+	)
+	[
+	    wf_width(wf),
+		wf_height(wf),
+		wf_weights(wf),
+		concat(
+		    rowsBeforeY,
+			[newRowY],
+			rowsAfterY
+		)
+	];
+
 width = len(sample[0]);
 height = len(sample);
 weights = weightsOfTiles(sample);
 
 wf = waveFunction(width, height, weights);
-eigenstates = initialEigenstates(width, height, weights);
 
 assert(wf_width(wf) == width);
 assert(wf_height(wf) == height);
-assert(wf_eigenstates(wf) == eigenstates);
+assert(wf_eigenstates(wf) == initialEigenstates(width, height, weights));
 assert(wf_isAllCollapsed(wf) == false);
 assert(wf_remove(wf, 0, 0, []) == wf);
 assert(wf_eigenstates_at(wf_remove(wf, 0, 0, ["CE"]), 0, 0) == ["C0", "C1", "CS", "C2", "C3", "S", "CW", "CN", "L"]);
+for(y = [0:height - 1]) {
+	for(x = [0:width - 1]) {
+		assert(len(wf_eigenstates_at(wf_collapse(wf, x, y), x, y)) == 1);
+	}
+}
+