CustomShader

new Cesium.CustomShader(options)

A user defined GLSL shader used with ModelExperimental as well as Cesium3DTileset.

If texture uniforms are used, additional resource management must be done:

  • The update function must be called each frame. When a custom shader is passed to a ModelExperimental or a Cesium3DTileset, this step is handled automaticaly
  • CustomShader#destroy must be called when the custom shader is no longer needed to clean up GPU resources properly. The application is responsible for calling this method.

To enable the use of ModelExperimental in Cesium3DTileset, set ExperimentalFeatures.enableModelExperimental to true.

Name Type Description
options Object An object with the following options
Name Type Default Description
mode CustomShaderMode CustomShaderMode.MODIFY_MATERIAL optional The custom shader mode, which determines how the custom shader code is inserted into the fragment shader.
lightingModel LightingModel optional The lighting model (e.g. PBR or unlit). If present, this overrides the default lighting for the model.
isTranslucent Boolean false optional If set, the model will be rendered as translucent. This overrides the default settings for the model.
uniforms Object.<String, UniformSpecifier> optional A dictionary for user-defined uniforms. The key is the uniform name that will appear in the GLSL code. The value is an object that describes the uniform type and initial value
varyings Object.<String, VaryingType> optional A dictionary for declaring additional GLSL varyings used in the shader. The key is the varying name that will appear in the GLSL code. The value is the data type of the varying. For each varying, the declaration will be added to the top of the shader automatically. The caller is responsible for assigning a value in the vertex shader and using the value in the fragment shader.
vertexShaderText String optional The custom vertex shader as a string of GLSL code. It must include a GLSL function called vertexMain. See the example for the expected signature. If not specified, the custom vertex shader step will be skipped in the computed vertex shader.
fragmentShaderText String optional The custom fragment shader as a string of GLSL code. It must include a GLSL function called fragmentMain. See the example for the expected signature. If not specified, the custom fragment shader step will be skipped in the computed fragment shader.
Example:
var customShader = new CustomShader({
  uniforms: {
    u_colorIndex: {
      type: Cesium.UniformType.FLOAT,
      value: 1.0
    },
    u_normalMap: {
      type: Cesium.UniformType.SAMPLER_2D,
      value: new Cesium.TextureUniform({
        url: "http://example.com/normal.png"
      })
    }
  },
  varyings: {
    v_selectedColor: Cesium.VaryingType.VEC3
  },
  vertexShaderText: `
  void vertexMain(VertexInput vsInput, inout vec3 position) {
    v_selectedColor = mix(vsInput.attributes.color_0, vsInput.attributes.color_1, u_colorIndex);
    position += 0.1 * vsInput.attributes.normal;
  }
  `,
  fragmentShaderText: `
  void fragmentMain(FragmentInput fsInput, inout czm_modelMaterial material) {
    material.normal = texture2D(u_normalMap, fsInput.attributes.texCoord_0);
    material.diffuse = v_selectedColor;
  }
  `
});
Experimental

This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.

Methods

setUniform(uniformName, value)

Update the value of a uniform declared in the shader
Name Type Description
uniformName String The GLSL name of the uniform. This must match one of the uniforms declared in the constructor
value Boolean | Number | Cartesian2 | Cartesian3 | Cartesian4 | Matrix2 | Matrix3 | Matrix4 | String | Resource The new value of the uniform.