triangleIntersection.js

triangleIntersection.js

var VisMan = Symbol.for("VisMan")

var cesiumViewer = () => {
  return window[VisMan].cesiumViewer
}

var initCesiumViewer = () => {
  if(window.viewer && window.viewer.state && window.viewer.state.viewer) {
    window[VisMan].cesiumViewer = window.viewer.state.viewer
  } else {
    window[VisMan].cesiumViewer = findReactCesiumViewer("cesiumContainer-0")
  }
  return window[VisMan].cesiumViewer
}

 var findReactCesiumViewer = (cesiumId) => {
  let cesiumViewer = null
  const el = document.getElementById(cesiumId)
  for (let key in el) {
    if (key.startsWith('__reactInternalInstance$')) {
      const fiberNode = el[key];

      if (fiberNode && fiberNode.return && fiberNode.return.memoizedState.next.memoizedState) {
        cesiumViewer = fiberNode.return.memoizedState.next.memoizedState
      }
      break
    }
  }
  return cesiumViewer
}

var Cartesian3 = Cesium.Cartesian3
var Matrix4 = Cesium.Matrix4

var removeGeometryInstances = () => {
  let primitives = cesiumViewer().scene.primitives

  for( let idx=primitives.length-1; idx >= 0 ; idx-- ) {
    let primitive = cesiumViewer().scene.primitives.get( idx )
    if( Object.keys(primitive).indexOf('geometryInstances') >= 0) {
      cesiumViewer().scene.primitives.remove(primitive)
    }
  }
    cesiumViewer().scene.requestRender()

}

var addTriangles = (positions) => {
  var geometry = new Cesium.Geometry({
  attributes: {
    position: new Cesium.GeometryAttribute({
      componentDatatype: Cesium.ComponentDatatype.DOUBLE, // not FLOAT
      componentsPerAttribute: 3,
      values: positions
    }),
  //     normal: new Cesium.GeometryAttribute({
  //       componentDatatype: Cesium.ComponentDatatype.FLOAT,
  //       componentsPerAttribute: 3,
  //       values: normals
  //     })
    },

    // Don't need the following line if no vertices are shared.
    //indices: new Uint32Array([0, 1, 2, 3, 4, 5]),
    primitiveType: Cesium.PrimitiveType.TRIANGLES,
    boundingSphere: Cesium.BoundingSphere.fromVertices(positions)
  });

  var triangleInstance = new Cesium.GeometryInstance({
    geometry: geometry,
    attributes: {
      color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.RED)
    },
    show: new Cesium.ShowGeometryInstanceAttribute(true)
  });

  cesiumViewer().scene.primitives.add(new Cesium.Primitive({
    geometryInstances: [triangleInstance],
    asynchronous: false,
    appearance: new Cesium.PerInstanceColorAppearance({
      closed: true,
      translucent: false
    })
  }));

  cesiumViewer().scene.requestRender()
}

var transformPoints = (points, transformMat4) => {
  let out = new Float64Array( points.length )

  for( let idx=0; idx<points.length; idx+=3 ) {
    let x = points[idx]
    let y = points[idx+1]
    let z = points[idx+2]
    let cart3 = new Cartesian3(x, y, z)
    let transformed = Matrix4.multiplyByPoint( transformMat4, cart3, new Cartesian3 )
    out[idx] = transformed.x
    out[idx+1] = transformed.y
    out[idx+2] = transformed.z 
  }
  return out

}

initCesiumViewer()

removeGeometryInstances()
cesiumViewer().scene.requestRender()

var transformMat4 = cesiumViewer().scene._primitives._primitives[2].root.transform
var triPoints_modelSpace = [ 
0,10,20, 60,60,60, 10,10,60, 
0,0,20, 60,-60,60, 10,-10,60 ]

var transformed = transformPoints( triPoints_modelSpace, transformMat4 )
console.log(transformed)
addTriangles(transformed)