Add '3D'

3D

@@ -0,0 +1,71 @@
+```function triangleClipAgainstPlane(planeP, planeN, inTri) {
+  var outTri1 = Tri(), outTri2 = Tri();
+
+  planeN = normVector(planeN);
+
+  var d = function(p) {
+    p = normVector(p);
+    return(dotVector(planeN, p) - dotVector(planeN, planeP));
+  };
+
+  var inside_points = Tri(), 
+    nInsidePointCount = 0;
+  var outside_points = Tri(), 
+    nOutsidePointCount = 0;
+
+  var d0 = d(inTri[0]);
+  var d1 = d(inTri[1]);
+  var d2 = d(inTri[2]);
+
+  if (d0 >= 0) {
+    inside_points[nInsidePointCount] = inTri[0];
+    nInsidePointCount++;
+  } else {
+    outside_points[nOutsidePointCount] = inTri[0];
+    nOutsidePointCount++;
+  }
+  if (d1 >= 0) {
+    inside_points[nInsidePointCount] = inTri[1];
+    nInsidePointCount++;
+  } else { 
+    outside_points[nOutsidePointCount] = inTri[1]; 
+    nOutsidePointCount++;
+  }
+  if (d2 >= 0) {
+    inside_points[nInsidePointCount] = inTri[2];
+    nInsidePointCount++;
+  } else {
+    outside_points[nOutsidePointCount] = inTri[2];
+    nOutsidePointCount++;
+  }
+  if (nInsidePointCount === 0) {
+    return [0];
+  }
+
+  if (nInsidePointCount === 3) {
+    outTri1 = inTri;
+        
+    return [1, [[outTri1[0], outTri1[1], outTri1[2]]]];
+  }
+
+  if (nInsidePointCount === 1 && nOutsidePointCount === 2) {
+    outTri1[0] = inside_points[0];
+
+    outTri1[1] = planeIntersectVector(planeP, planeN, inside_points[0], outside_points[0]);
+    outTri1[2] = planeIntersectVector(planeP, planeN, inside_points[0], outside_points[1]);
+
+    return [1, [[outTri1[0], outTri1[1], outTri1[2]]]];
+  }
+    
+  if (nInsidePointCount === 2 && nOutsidePointCount === 1) {
+    outTri1[0] = inside_points[0];
+    outTri1[1] = inside_points[1];
+    outTri1[2] = planeIntersectVector(planeP, planeN, inside_points[0], outside_points[0]);
+
+    outTri2[0] = inside_points[1];
+    outTri2[1] = outTri1[2];
+    outTri2[2] = planeIntersectVector(planeP, planeN, inside_points[1], outside_points[0]);
+
+    return [2, [[outTri1[0], outTri1[1], outTri1[2]], [outTri2[0], outTri2[1], outTri2[2]]]];
+  }
+};```