# PostProcessStage

#### new Cesium.PostProcessStage(options)
Scene/PostProcessStage.js 95

Runs a post-process stage on either the texture rendered by the scene or the output of a previous post-process stage.

Name | Type | Description
--- | --- | ---
`options` | Object | An object with the following properties:
Name | Type | Default | Description
--- | --- | --- | ---
`fragmentShader` | String |  | The fragment shader to use. The default `sampler2D` uniforms are `colorTexture` and `depthTexture`. The color texture is the output of rendering the scene or the previous stage. The depth texture is the output from rendering the scene. The shader should contain one or both uniforms. There is also a `vec2` varying named `v_textureCoordinates` that can be used to sample the textures.
`uniforms` | Object |  | optional An object whose properties will be used to set the shaders uniforms. The properties can be constant values or a function. A constant value can also be a URI, data URI, or HTML element to use as a texture.
`textureScale` | Number | `1.0` | optional A number in the range (0.0, 1.0] used to scale the texture dimensions. A scale of 1.0 will render this post-process stage to a texture the size of the viewport.
`forcePowerOfTwo` | Boolean | `false` | optional Whether or not to force the texture dimensions to be both equal powers of two. The power of two will be the next power of two of the minimum of the dimensions.
`sampleMode` | PostProcessStageSampleMode | `PostProcessStageSampleMode.NEAREST` | optional How to sample the input color texture.
`pixelFormat` | PixelFormat | `PixelFormat.RGBA` | optional The color pixel format of the output texture.
`pixelDatatype` | PixelDatatype | `PixelDatatype.UNSIGNED_BYTE` | optional The pixel data type of the output texture.
`clearColor` | Color | `Color.BLACK` | optional The color to clear the output texture to.
`scissorRectangle` | BoundingRectangle |  | optional The rectangle to use for the scissor test.
`name` | String | `createGuid()` | optional The unique name of this post-process stage for reference by other stages in a composite. If a name is not supplied, a GUID will be generated.

##### Throws:

- DeveloperError : options.textureScale must be greater than 0.0 and less than or equal to 1.0.
- DeveloperError : options.pixelFormat must be a color format.
- DeveloperError : When options.pixelDatatype is FLOAT, this WebGL implementation must support the OES_texture_float extension. Check context.floatingPointTexture.

##### Examples:

    // Simple stage to change the color
    var fs =
        'uniform sampler2D colorTexture;\n' +
        'varying vec2 v_textureCoordinates;\n' +
        'uniform float scale;\n' +
        'uniform vec3 offset;\n' +
        'void main() {\n' +
        '    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n' +
        '    gl_FragColor = vec4(color.rgb * scale + offset, 1.0);\n' +
        '}\n';
    scene.postProcessStages.add(new Cesium.PostProcessStage({
        fragmentShader : fs,
        uniforms : {
            scale : 1.1,
            offset : function() {
                return new Cesium.Cartesian3(0.1, 0.2, 0.3);
            }
        }
    }));

    // Simple stage to change the color of what is selected.
    // If czm_selected returns true, the current fragment belongs to geometry in the selected array.
    var fs =
        'uniform sampler2D colorTexture;\n' +
        'varying vec2 v_textureCoordinates;\n' +
        'uniform vec4 highlight;\n' +
        'void main() {\n' +
        '    vec4 color = texture2D(colorTexture, v_textureCoordinates);\n' +
        '    if (czm_selected()) {\n' +
        '        vec3 highlighted = highlight.a * highlight.rgb + (1.0 - highlight.a) * color.rgb;\n' +
        '        gl_FragColor = vec4(highlighted, 1.0);\n' +
        '    } else { \n' +
        '        gl_FragColor = color;\n' +
        '    }\n' +
        '}\n';
    var stage = scene.postProcessStages.add(new Cesium.PostProcessStage({
        fragmentShader : fs,
        uniforms : {
            highlight : function() {
                return new Cesium.Color(1.0, 0.0, 0.0, 0.5);
            }
        }
    }));
    stage.selected = [cesium3DTileFeature];

##### See:

- PostProcessStageComposite

### Members

#### readonly clearColor : Color
Scene/PostProcessStage.js 323

The color to clear the output texture to.

#### enabled : Boolean
Scene/PostProcessStage.js 182

Whether or not to execute this post-process stage when ready.

#### readonly forcePowerOfTwo : Number
Scene/PostProcessStage.js 275

Whether or not to force the output texture dimensions to be both equal powers of two. The power of two will be the next power of two of the minimum of the dimensions.

#### readonly fragmentShader : String
Scene/PostProcessStage.js 228

The fragment shader to use when execute this post-process stage.

The shader must contain a sampler uniform declaration for `colorTexture`, `depthTexture`, or both.

The shader must contain a `vec2` varying declaration for `v_textureCoordinates` for sampling the texture uniforms.

#### readonly name : String
Scene/PostProcessStage.js 208

The unique name of this post-process stage for reference by other stages in a `PostProcessStageComposite`.

#### readonly pixelDatatype : PixelDatatype
Scene/PostProcessStage.js 311

The pixel data type of the output texture.

#### readonly pixelFormat : PixelFormat
Scene/PostProcessStage.js 299

The color pixel format of the output texture.

#### readonly ready : Boolean
Scene/PostProcessStage.js 196

Determines if this post-process stage is ready to be executed. A stage is only executed when both `ready` and `PostProcessStage#enabled` are `true`. A stage will not be ready while it is waiting on textures to load.

#### readonly sampleMode : PostProcessStageSampleMode
Scene/PostProcessStage.js 287

How to sample the input color texture.

#### readonly scissorRectangle : BoundingRectangle
Scene/PostProcessStage.js 335

The `BoundingRectangle` to use for the scissor test. A default bounding rectangle will disable the scissor test.

#### selected : Array
Scene/PostProcessStage.js 376

The features selected for applying the post-process.

In the fragment shader, use `czm_selected` to determine whether or not to apply the post-process stage to that fragment. For example: `if (czm_selected(v_textureCoordinates)) { // apply post-process stage } else { gl_FragColor = texture2D(colorTexture, v_textureCordinates); }`

#### readonly textureScale : Number
Scene/PostProcessStage.js 263

A number in the range (0.0, 1.0] used to scale the output texture dimensions. A scale of 1.0 will render this post-process stage to a texture the size of the viewport.

#### readonly uniforms : Object
Scene/PostProcessStage.js 251

An object whose properties are used to set the uniforms of the fragment shader.

The object property values can be either a constant or a function. The function will be called each frame before the post-process stage is executed.

A constant value can also be a URI to an image, a data URI, or an HTML element that can be used as a texture, such as HTMLImageElement or HTMLCanvasElement.

If this post-process stage is part of a `PostProcessStageComposite` that does not execute in series, the constant value can also be the name of another stage in a composite. This will set the uniform to the output texture the stage with that name.

### Methods

#### destroy()
Scene/PostProcessStage.js 1017

Destroys the WebGL resources held by this object. Destroying an object allows for deterministic release of WebGL resources, instead of relying on the garbage collector to destroy this object.

Once an object is destroyed, it should not be used; calling any function other than `isDestroyed` will result in a `DeveloperError` exception. Therefore, assign the return value (`undefined`) to the object as done in the example.

##### Throws:

- DeveloperError : This object was destroyed, i.e., destroy() was called.

##### See:

- PostProcessStage#isDestroyed

#### isDestroyed() → Boolean
Scene/PostProcessStage.js 1000

Returns true if this object was destroyed; otherwise, false.

If this object was destroyed, it should not be used; calling any function other than `isDestroyed` will result in a `DeveloperError` exception.

##### Returns:

`true` if this object was destroyed; otherwise, `false`.

##### See:

- PostProcessStage#destroy