diff --git a/src/geo/base.js b/src/geo/base.js
index 2e468fd1..dcace90e 100644
--- a/src/geo/base.js
+++ b/src/geo/base.js
@@ -410,6 +410,7 @@ function orderClosest(array, fn, from) {
 // an unwrapped array in the original dimensions
 function triangulate(array, holes, dims) {
     let narray;
+    let info;
     if (dims === 2) {
         narray = array;
     } else {
@@ -434,6 +435,7 @@ function triangulate(array, holes, dims) {
                 d1 = i;
             }
         }
+        info = { d1, d2, dmax, delta: delta.slice() };
         delta[d1] = dmax = 0;
         for (let i = 0; i < dims; i++) {
             if (delta[i] > dmax) {
@@ -455,6 +457,9 @@ function triangulate(array, holes, dims) {
             oa[e++] = array[ai + j];
         }
     }
+    if (oa.length === 0) {
+        console.log('debug_triangulate', {array, oa, info});
+    }
     return oa;
 }
 
diff --git a/src/geo/csg.js b/src/geo/csg.js
index 1c76efcf..2554e70f 100644
--- a/src/geo/csg.js
+++ b/src/geo/csg.js
@@ -13,11 +13,13 @@ const CSG = {
 
     union() {
         if (debug) {
-            for (let p of [ ...arguments ].map(a => a.polygons.map(p => p.vertices))) {
-                console.log(JSON.stringify(p));
-            }
+            console.log(JSON.stringify([ ...arguments ]));
         }
-        return jscadModeling.booleans.union(...arguments);
+        let union = jscadModeling.booleans.union(...arguments);
+        if (debug) {
+            console.log(JSON.stringify(union));
+        }
+        return union;
     },
 
     subtract() {
@@ -29,10 +31,21 @@ const CSG = {
     },
 
     toPositionArray(geom) {
-        return geom.polygons
-            .map(p => p.vertices.flat())
-            .map(a => base.util.triangulate(a, undefined, 3))
-            .flat().toFloat32();
+        const out = [];
+        const poly = jscadModeling.geometries.geom3
+            .toPolygons(geom)
+            .map(p => p.vertices);
+        for (let p of poly) {
+            let p0 = p[0];
+            for (let i = 0; i<p.length - 2; i++) {
+                out.push(p0, p[i+1], p[i+2]);
+            }
+        }
+        return out.flat().toFloat32();
+        // return geom.polygons
+        //     .map(p => p.vertices.flat())
+        //     .map(a => base.util.triangulate(a, undefined, 3))
+        //     .flat().toFloat32();
     },
 
     // Construct a CSG from a THREE Geometry BufferAttribute array (or similar)