cesium 雷达扫描

内容概览

1.基于cesium 实现雷达扫描
2.源代码 demo 下载

本篇实现 cesium 雷达扫描功能，效果图如下：

实现思路：核心引用 cesium PostProcessStage 类

• 核心代码

    /*
        添加雷达扫描线 地形遮挡开启   lon:-74.01296152309055 lat:40.70524201566827 height:129.14366696393927
        viewer
        cartographicCenter 扫描中心
        radius  半径 米
        scanColor 扫描颜色
        duration 持续时间 毫秒
      */
      function AddRadarScanPostStage(viewer, cartographicCenter, radius, scanColor, duration) {
          var ScanSegmentShader =
              "uniform sampler2D colorTexture;\n" +
              "uniform sampler2D depthTexture;\n" +
              "varying vec2 v_textureCoordinates;\n" +
              "uniform vec4 u_scanCenterEC;\n" +
              "uniform vec3 u_scanPlaneNormalEC;\n" +
              "uniform vec3 u_scanLineNormalEC;\n" +
              "uniform float u_radius;\n" +
              "uniform vec4 u_scanColor;\n" +
              "vec4 toEye(in vec2 uv, in float depth)\n" +
              " {\n" +
                " vec2 xy = vec2((uv.x * 2.0 - 1.0),(uv.y * 2.0 - 1.0));\n" +
                " vec4 posInCamera =czm_inverseProjection * vec4(xy, depth, 1.0);\n" +
                " posInCamera =posInCamera / posInCamera.w;\n" +
                " return posInCamera;\n" +
              " }\n" +
              "bool isPointOnLineRight(in vec3 ptOnLine, in vec3 lineNormal, in vec3 testPt)\n" +
              "{\n" +
                  "vec3 v01 = testPt - ptOnLine;\n" +
                  "normalize(v01);\n" +
                  "vec3 temp = cross(v01, lineNormal);\n" +
                  "float d = dot(temp, u_scanPlaneNormalEC);\n" +
                  "return d > 0.5;\n" +
              "}\n" +
              "vec3 pointProjectOnPlane(in vec3 planeNormal, in vec3 planeOrigin, in vec3 point)\n" +
              "{\n" +
                  "vec3 v01 = point -planeOrigin;\n" +
                  "float d = dot(planeNormal, v01) ;\n" +
                  "return (point - planeNormal * d);\n" +
               "}\n" +
               "float distancePointToLine(in vec3 ptOnLine, in vec3 lineNormal, in vec3 testPt)\n" +
               "{\n" +
                  "vec3 tempPt = pointProjectOnPlane(lineNormal, ptOnLine, testPt);\n" +
                  "return length(tempPt - ptOnLine);\n" +
                "}\n" +
               "float getDepth(in vec4 depth)\n" +
               "{\n" +
                  "float z_window = czm_unpackDepth(depth);\n" +
                  "z_window = czm_reverseLogDepth(z_window);\n" +
                  "float n_range = czm_depthRange.near;\n" +
                  "float f_range = czm_depthRange.far;\n" +
                  "return (2.0 * z_window - n_range - f_range) / (f_range - n_range);\n" +
               "}\n" +
               "void main()\n" +
               "{\n" +
                  "gl_FragColor = texture2D(colorTexture, v_textureCoordinates);\n" +
                  "float depth = getDepth( texture2D(depthTexture, v_textureCoordinates));\n" +
                  "vec4 viewPos = toEye(v_textureCoordinates, depth);\n" +
                  "vec3 prjOnPlane = pointProjectOnPlane(u_scanPlaneNormalEC.xyz, u_scanCenterEC.xyz, viewPos.xyz);\n" +
                  "float dis = length(prjOnPlane.xyz - u_scanCenterEC.xyz);\n" +
                  "float twou_radius = u_radius * 2.0;\n" +
                  "if(dis < u_radius)\n" +
                   "{\n" +
                      "float f0 = 1.0 -abs(u_radius - dis) / u_radius;\n" +
                      "f0 = pow(f0, 64.0);\n" +
                      "vec3 lineEndPt = vec3(u_scanCenterEC.xyz) + u_scanLineNormalEC * u_radius;\n" +
                      "float f = 0.0;\n" +
                      "if(isPointOnLineRight(u_scanCenterEC.xyz, u_scanLineNormalEC.xyz, prjOnPlane.xyz))\n" +
                      "{\n" +
                          "float dis1= length(prjOnPlane.xyz - lineEndPt);\n" +
                          "f = abs(twou_radius -dis1) / twou_radius;\n" +
                          "f = pow(f, 3.0);\n" +
                      "}\n" +
                      "gl_FragColor = mix(gl_FragColor, u_scanColor, f + f0);\n" +
                   "}\n" +
                "}\n";
          var _Cartesian3Center = Cesium.Cartographic.toCartesian(cartographicCenter);
          var _Cartesian4Center = new Cesium.Cartesian4(_Cartesian3Center.x, _Cartesian3Center.y, _Cartesian3Center.z, 1);
          var _CartographicCenter1 = new Cesium.Cartographic(cartographicCenter.longitude, cartographicCenter.latitude, cartographicCenter.height + 500);
          var _Cartesian3Center1 = Cesium.Cartographic.toCartesian(_CartographicCenter1);
          var _Cartesian4Center1 = new Cesium.Cartesian4(_Cartesian3Center1.x, _Cartesian3Center1.y, _Cartesian3Center1.z, 1);
          var _CartographicCenter2 = new Cesium.Cartographic(cartographicCenter.longitude + Cesium.Math.toRadians(0.001), cartographicCenter.latitude, cartographicCenter.height);
          var _Cartesian3Center2 = Cesium.Cartographic.toCartesian(_CartographicCenter2);
          var _Cartesian4Center2 = new Cesium.Cartesian4(_Cartesian3Center2.x, _Cartesian3Center2.y, _Cartesian3Center2.z, 1);
          var _RotateQ = new Cesium.Quaternion();
          var _RotateM = new Cesium.Matrix3();
          var _time = (new Date()).getTime();
          var _scratchCartesian4Center = new Cesium.Cartesian4();
          var _scratchCartesian4Center1 = new Cesium.Cartesian4();
          var _scratchCartesian4Center2 = new Cesium.Cartesian4();
          var _scratchCartesian3Normal = new Cesium.Cartesian3();
          var _scratchCartesian3Normal1 = new Cesium.Cartesian3();
          var ScanPostStage = new Cesium.PostProcessStage({
              fragmentShader: ScanSegmentShader,
              uniforms: {
                  u_scanCenterEC: function () {
                      return Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center, _scratchCartesian4Center);
                  },
                  u_scanPlaneNormalEC: function () {
                      var temp = Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center, _scratchCartesian4Center);
                      var temp1 = Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center1, _scratchCartesian4Center1);
                      _scratchCartesian3Normal.x = temp1.x - temp.x;
                      _scratchCartesian3Normal.y = temp1.y - temp.y;
                      _scratchCartesian3Normal.z = temp1.z - temp.z;
                      Cesium.Cartesian3.normalize(_scratchCartesian3Normal, _scratchCartesian3Normal);
                      return _scratchCartesian3Normal;
                  },
                  u_radius: radius,
                  u_scanLineNormalEC: function () {
                      var temp = Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center, _scratchCartesian4Center);
                      var temp1 = Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center1, _scratchCartesian4Center1);
                      var temp2 = Cesium.Matrix4.multiplyByVector(viewer.camera._viewMatrix, _Cartesian4Center2, _scratchCartesian4Center2);
                      _scratchCartesian3Normal.x = temp1.x - temp.x;
                      _scratchCartesian3Normal.y = temp1.y - temp.y;
                      _scratchCartesian3Normal.z = temp1.z - temp.z;
                      Cesium.Cartesian3.normalize(_scratchCartesian3Normal, _scratchCartesian3Normal);
                      _scratchCartesian3Normal1.x = temp2.x - temp.x;
                      _scratchCartesian3Normal1.y = temp2.y - temp.y;
                      _scratchCartesian3Normal1.z = temp2.z - temp.z;
                      var tempTime = (((new Date()).getTime() - _time) % duration) / duration;
                      Cesium.Quaternion.fromAxisAngle(_scratchCartesian3Normal, tempTime * Cesium.Math.PI * 2, _RotateQ);
                      Cesium.Matrix3.fromQuaternion(_RotateQ, _RotateM);
                      Cesium.Matrix3.multiplyByVector(_RotateM, _scratchCartesian3Normal1, _scratchCartesian3Normal1);
                      Cesium.Cartesian3.normalize(_scratchCartesian3Normal1, _scratchCartesian3Normal1);
                      return _scratchCartesian3Normal1;
                  },
                  u_scanColor: scanColor
              }
          });
          viewer.scene.postProcessStages.add(ScanPostStage);
      }
  

参考文献：
blog.sina.com.cn/s/blog_15e8…
github.com/YanzheZhang…

link==>