Extend example

    private final String pawns = GWT.getModuleBaseURL() + "SampleData/models/CesiumDrone/Pawns.glb";

    private final String milkTruck = GWT.getModuleBaseURL() + "SampleData/models/CesiumMilkTruck/CesiumMilkTruck.glb";

    private final String groundVehicle = GWT.getModuleBaseURL() + "SampleData/models/GroundVehicle/GroundVehicle.glb";

    private final String pointCloudWave = GWT.getModuleBaseURL() + "SampleData/models/PointCloudWave/PointCloudWave.glb";

    private CustomShader expandModelShader;

    private CustomShader textureUniformShader;

    private CustomShader checkerboardHolesShader;

    private CustomShader gradientShader;

    private CustomShader modifyPbrShader;

    private CustomShader pointCloudWaveShader;

    private boolean needsDrag = false;

    private boolean dragActive = false;

                        "}",

                })));

        pointCloudWaveShader = new CustomShader(new CustomShaderOptions()

                .addUniform("u_time", UniformType.FLOAT(), 0)

                .setVertexShaderText(String.join("\n", new String[] {

                        "void vertexMain(VertexInput vsInput, inout czm_modelVertexOutput vsOutput)",

                        "{",

                        // This model's x and y coordinates are in the range [0, 1], which

                        // conveniently doubles as UV coordinates.

                        "    vec2 uv = vsInput.attributes.positionMC.xy;",

                        // Make the point cloud undulate in a complex wave that varies in

                        // both space and time. The amplitude is based on the original shape

                        // of the point cloud (which already is a wavy surface). The wave

                        // is computed relative to the center of the model, hence the

                        // transformations from [0, 1] -> [-1, 1] -> [0, 1]

                        "    float amplitude = 2.0 * vsInput.attributes.positionMC.z - 1.0;",

                        "    float wave = amplitude * sin(2.0 * czm_pi * uv.x - 2.0 * u_time) * sin(u_time);",

                        "    vsOutput.positionMC.z = 0.5 + 0.5 * wave;",

                        // Make the points pulse in and out by changing their size

                        "    vsOutput.pointSize = 10.0 + 5.0 * sin(u_time);",

                        "}",

                }))

                .setFragmentShaderText(String.join("\n", new String[] {

                        "void fragmentMain(FragmentInput fsInput, inout czm_modelMaterial material)",

                        "{",

                        // Make the points circular instead of square

                        "    float distance = length(gl_PointCoord - 0.5);",

                        "    if (distance > 0.5) {",

                        "        discard;",

                        "    }",

                        // Make a sinusoid color palette that moves in the general direction

                        // of the wave, but at a different speed.

                        // Coefficients were chosen arbitrarily

                        "    vec2 uv = fsInput.attributes.positionMC.xy;",

                        "    material.diffuse = 0.2 * fsInput.attributes.color_0.rgb;",

                        "    material.diffuse += vec3(0.2, 0.3, 0.4) + vec3(0.2, 0.3, 0.4) * sin(2.0 * czm_pi * vec3(3.0, 2.0, 1.0) * uv.x - 3.0 * u_time);",

                        "}",

                })));

        // Event handlers =====================================================

        double startTime = performanceNow();

        csVPanel.getViewer().scene().postUpdate().addEventListener((Event.Listener) o -> textureUniformShader.setUniform("u_time", (performanceNow() - startTime) / 1000));

        csVPanel.getViewer().scene().postUpdate().addEventListener((Event.Listener) o -> {

            double elapsedTimeSeconds = (performanceNow() - startTime) / 1000;

            textureUniformShader.setUniform("u_time", elapsedTimeSeconds);

            pointCloudWaveShader.setUniform("u_time", elapsedTimeSeconds);

        });

        Cartesian2 dragCenter = new Cartesian2();

        csVPanel.getViewer().screenSpaceEventHandler().setInputAction(event -> {

        listBox.addItem("Procedural Gradient Texture");

        listBox.addItem("Modify PBR values via Mouse Drag");

        listBox.addItem("Expand Model via Mouse Drag");

        listBox.addItem("Animated Point Cloud");

        listBox.addChangeHandler(event -> {

            String value = ((ListBox) event.getSource()).getSelectedItemText();

            switch (value) {

                case "Procedural Gradient Texture": selectModel(balloon, gradientShader); needsDrag = false; break;

                case "Modify PBR values via Mouse Drag": selectModel(groundVehicle, modifyPbrShader); needsDrag = true; break;

                case "Expand Model via Mouse Drag": selectModel(milkTruck, expandModelShader); needsDrag = true; break;

                case "Animated Point Cloud": selectModel(pointCloudWave, pointCloudWaveShader); needsDrag = false; break;

                default: break;

            }

        });