{
 "id": "37-pyramid-apex-blend",
 "name": "Pyramid apex: 4-edge corner blend",
 "description": "Loft from a 40x40 square (XY) to a point at (0,0,30) = square pyramid; all edges filleted R2 (apex blends 4 edges).",
 "exercises": [
  "loft_to_point",
  "fillet",
  "corner_blend_4"
 ],
 "units": {
  "length": "mm",
  "angle": "deg",
  "area": "mm2",
  "volume": "mm3"
 },
 "conventions": {
  "world": "right-handed; Z up. XY/XZ/YZ are the origin planes.",
  "sketch_frame": "sketch-local 2D coords; world = plane.origin + x*plane.x_dir + y*plane.y_dir (origin in mm). Profile 'loops' list sketch entity ids.",
  "point_refs": "'<id>.start' / '<id>.end' / '<id>.center' reuse (share) that existing sketch point; 'at' is its position when referenced.",
  "extrude_direction": "positive = along sketch plane normal unless stated",
  "selections": "selected faces/edges carry 'point': a world-space point on the face / the edge's parametric midpoint; pick the nearest face/edge to it."
 },
 "parameters": [],
 "features": [
  {
   "op": "sketch",
   "name": "Base",
   "plane": {
    "ref": "XY",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     1.0,
     0.0,
     0.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     0.0,
     0.0,
     1.0
    ]
   },
   "entities": [
    {
     "type": "line",
     "start": {
      "at": [
       -20,
       -20
      ]
     },
     "end": {
      "at": [
       20,
       -20
      ]
     },
     "id": "l1"
    },
    {
     "type": "line",
     "start": {
      "ref": "l1.end",
      "at": [
       20.0,
       -20.0
      ]
     },
     "end": {
      "at": [
       20,
       20
      ]
     },
     "id": "l2"
    },
    {
     "type": "line",
     "start": {
      "ref": "l2.end",
      "at": [
       20.0,
       20.0
      ]
     },
     "end": {
      "at": [
       -20,
       20
      ]
     },
     "id": "l3"
    },
    {
     "type": "line",
     "start": {
      "ref": "l3.end",
      "at": [
       -20.0,
       20.0
      ]
     },
     "end": {
      "ref": "l1.start",
      "at": [
       -20.0,
       -20.0
      ]
     },
     "id": "l4"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "construction_plane",
   "name": "Apex30",
   "method": "offset",
   "base": "XY",
   "offset": 30
  },
  {
   "op": "sketch",
   "name": "Apex",
   "plane": {
    "ref": "construction plane Apex30 (XY offset 30)",
    "origin": [
     0.0,
     0.0,
     30.0
    ],
    "x_dir": [
     1.0,
     0.0,
     0.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     0.0,
     0.0,
     1.0
    ]
   },
   "entities": [
    {
     "type": "point",
     "at": [
      0,
      0
     ],
     "fixed": false,
     "id": "p1"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "loft",
   "name": "Loft1",
   "operation": "new",
   "sections": [
    {
     "sketch": "Base",
     "loops": [
      {
       "outer": true,
       "curves": [
        "l1",
        "l2",
        "l3",
        "l4"
       ]
      }
     ]
    },
    {
     "sketch": "Apex",
     "point": "p1",
     "world": [
      0,
      0,
      30
     ]
    }
   ],
   "end_conditions": "free",
   "solid": true,
   "result_bodies": [
    "Pyramid"
   ]
  },
  {
   "op": "fillet",
   "name": "Fillet1",
   "type": "constant_radius",
   "radius": 2,
   "tangent_chain": false,
   "edge_selection": "all 8 edges of the pyramid",
   "edges": [
    {
     "type": "line",
     "start": [
      -20.0,
      20.0,
      0.0
     ],
     "end": [
      -20.0,
      -20.0,
      0.0
     ],
     "point": [
      -20.0,
      0.0,
      0.0
     ]
    },
    {
     "type": "line",
     "start": [
      20.0,
      20.0,
      0.0
     ],
     "end": [
      -20.0,
      20.0,
      0.0
     ],
     "point": [
      0.0,
      20.0,
      0.0
     ]
    },
    {
     "type": "line",
     "start": [
      20.0,
      -20.0,
      0.0
     ],
     "end": [
      20.0,
      20.0,
      0.0
     ],
     "point": [
      20.0,
      0.0,
      0.0
     ]
    },
    {
     "type": "line",
     "start": [
      -20.0,
      -20.0,
      0.0
     ],
     "end": [
      20.0,
      -20.0,
      0.0
     ],
     "point": [
      0.0,
      -20.0,
      0.0
     ]
    },
    {
     "type": "line",
     "start": [
      -20.0,
      -20.0,
      0.0
     ],
     "end": [
      0.0,
      0.0,
      30.0
     ],
     "point": [
      -10.0,
      -10.0,
      15.0
     ]
    },
    {
     "type": "line",
     "start": [
      -20.0,
      20.0,
      0.0
     ],
     "end": [
      0.0,
      0.0,
      30.0
     ],
     "point": [
      -10.0,
      10.0,
      15.0
     ]
    },
    {
     "type": "line",
     "start": [
      20.0,
      -20.0,
      0.0
     ],
     "end": [
      0.0,
      0.0,
      30.0
     ],
     "point": [
      10.0,
      -10.0,
      15.0
     ]
    },
    {
     "type": "line",
     "start": [
      20.0,
      20.0,
      0.0
     ],
     "end": [
      0.0,
      0.0,
      30.0
     ],
     "point": [
      10.0,
      10.0,
      15.0
     ]
    }
   ]
  }
 ]
}