```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]]]];
  }
};```