1 var modelEntityClippingPlanes;//定义的裁剪平面集合
 2 function loadModel(url) {
 3     var clippingPlanes = [
 4         new Cesium.ClippingPlane(new Cesium.Cartesian3(0.0, 0.0, -1.0), -100.0)
 5     ];//裁剪平面数组
 6
 7     modelEntityClippingPlanes = new Cesium.ClippingPlaneCollection({
 8         planes : clippingPlanes,
 9         edgeWidth : viewModel.edgeStylingEnabled ? 1.0 : 0.0
10     });
11 　　//更新裁剪平面的位置
12     function updateClippingPlanes() {
13         return modelEntityClippingPlanes;
14     }
15 　　//添加要裁剪的飞机模型，并设置裁剪平面
16     var position = Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706, 100.0);
17     var heading = Cesium.Math.toRadians(135.0);
18     var pitch = 0.0;
19     var roll = 0.0;
20     var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);
21     var orientation = Cesium.Transforms.headingPitchRollQuaternion(position, hpr);
22     var entity = viewer.entities.add({
23         name : url,
24         position : position,
25         orientation : orientation,
26         model : {
27             uri : url,
28             scale : 8,
29             minimumPixelSize : 100.0,
30             clippingPlanes : new Cesium.CallbackProperty(updateClippingPlanes, false)//重要，设置裁剪平面的地方
31         }
32     });
33
34     viewer.trackedEntity = entity;
35 　　//将绘制的裁剪平面绘制到场景中
36     for (var i = 0; i < clippingPlanes.length; ++i) {
37         var plane = clippingPlanes[i];
38         var planeEntity = viewer.entities.add({
39             position : position,
40             plane : {
41                 dimensions : new Cesium.Cartesian2(300.0, 300.0),
42                 material : Cesium.Color.WHITE.withAlpha(0.1),
43                 plane : new Cesium.CallbackProperty(createPlaneUpdateFunction(plane, Cesium.Matrix4.IDENTITY), false),
44                 outline : true,
45                 outlineColor : Cesium.Color.WHITE
46             }
47         });
48
49         planeEntities.push(planeEntity);
50     }
51 }

 1 precision highp float;
 2 varying vec3 v_normal;
 3 varying vec2 v_texcoord0;
 4 uniform sampler2D u_diffuse;
 5 uniform vec4 u_specular;
 6 uniform float u_shininess;
 7 void gltf_clip_main() {
 8 vec3 normal = normalize(v_normal);
 9 vec4 color = vec4(0., 0., 0., 0.);
10 vec4 diffuse = vec4(0., 0., 0., 1.);
11 vec4 specular;
12 diffuse = texture2D(u_diffuse, v_texcoord0);
13 specular = u_specular;
14 diffuse.xyz *= max(dot(normal,vec3(0.,0.,1.)), 0.);
15 color.xyz += diffuse.xyz;
16 color = vec4(color.rgb * diffuse.a, diffuse.a);
17 gl_FragColor = color;
18 }
19 vec4 getClippingPlane(sampler2D packedClippingPlanes, int clippingPlaneNumber, mat4 transform)
20 {
21     int pixY = clippingPlaneNumber / 1;
22     int pixX = clippingPlaneNumber - (pixY * 1);
23     float u = (float(pixX) + 0.5) * 1.0;
24     float v = (float(pixY) + 0.5) * 0.5;
25     vec4 plane = texture2D(packedClippingPlanes, vec2(u, v));
26     return czm_transformPlane(plane, transform);
27 }
28
29 float clip(vec4 fragCoord, sampler2D clippingPlanes, mat4 clippingPlanesMatrix)
30 {
31     bool clipped = true;
32     vec4 position = czm_windowToEyeCoordinates(fragCoord);
33     vec3 clipNormal = vec3(0.0);
34     vec3 clipPosition = vec3(0.0);
35     float clipAmount = 0.0;
36     float pixelWidth = czm_metersPerPixel(position);
37     for (int i = 0; i < 1; ++i)
38     {
39         vec4 clippingPlane = getClippingPlane(clippingPlanes, i, clippingPlanesMatrix);
40         clipNormal = clippingPlane.xyz;
41         clipPosition = -clippingPlane.w * clipNormal;
42         float amount = dot(clipNormal, (position.xyz - clipPosition)) / pixelWidth;
43         clipAmount = max(amount, clipAmount);
44         clipped = clipped && (amount <= 0.0);
45     }
46     if (clipped)
47     {
48         discard;
49     }
50     return clipAmount;
51 }
52
53 uniform sampler2D gltf_clippingPlanes;
54 uniform mat4 gltf_clippingPlanesMatrix;
55 uniform vec4 gltf_clippingPlanesEdgeStyle;
56 void main()
57 {
58     gltf_clip_main();
59     float clipDistance = clip(gl_FragCoord, gltf_clippingPlanes, gltf_clippingPlanesMatrix);
60     vec4 clippingPlanesEdgeColor = vec4(1.0);
61     clippingPlanesEdgeColor.rgb = gltf_clippingPlanesEdgeStyle.rgb;
62     float clippingPlanesEdgeWidth = gltf_clippingPlanesEdgeStyle.a;
63     if (clipDistance > 0.0 && clipDistance < clippingPlanesEdgeWidth)
64     {
65         gl_FragColor = clippingPlanesEdgeColor;
66     }
67 }