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+<!DOCTYPE html>
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+<html lang="en">
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+ <head>
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+ <meta charset="utf-8">
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+ <base href="../../../" />
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+ <script src="list.js"></script>
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+ <script src="page.js"></script>
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+ <link type="text/css" rel="stylesheet" href="page.css" />
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+ </head>
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+ <body>
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+ <h1>How to use post-processing</h1>
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+
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+ <p>
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+ Many three.js applications render their 3D objects directly to the screen. Sometimes, however, you want to apply one or more graphical
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+ effects like Depth-Of-Field, Bloom, Film Grain or various types of Anti-aliasing. Post-processing is a widely used approach
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+ to implement such effects. First, the scene is rendered to a render target which represents a buffer in the video card's memory.
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+ In the next step one ore more post-processing passes apply filters and effects to the image buffer before it is eventually rendered to
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+ the screen.
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+ </p>
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+ <p>
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+ three.js provides a complete post-processing solution via [page:EffectComposer] to implement such a workflow.
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+ </p>
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+
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+ <h2>Workflow</h2>
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+
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+ <p>
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+ The first step in the process is to import all necessary files from the examples directory. The guide assumes your are using the official
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+ [link:https://www.npmjs.com/package/three npm package] of three.js. For our basic demo in this guide we need the following files.
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+ </p>
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+
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+ <code>
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+ import { EffectComposer } from 'three/examples/jsm/postprocessing/EffectComposer.js';
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+ import { RenderPass } from 'three/examples/jsm/postprocessing/RenderPass.js';
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+ import { GlitchPass } from 'three/examples/jsm/postprocessing/GlitchPass.js';
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+ </code>
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+
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+ <p>
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+ After all files are successfully imported, we can create our composer by passing in an instance of [page:WebGLRenderer].
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+ </p>
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+
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+ <code>
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+ var composer = new EffectComposer( renderer );
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+ </code>
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+
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+ <p>
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+ When using a composer, it's necessary to change the application's animation loop. Instead of calling the render method of
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+ [page:WebGLRenderer], we now use the respective counterpart of [page:EffectComposer].
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+ </p>
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+
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+ <code>
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+ function animate() {
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+
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+ requestAnimationFrame( animate );
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+
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+ composer.render();
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+
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+ }
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+ </code>
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+
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+ <p>
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+ Our composer is now ready so it's possible to configure the chain of post-processing passes. These passes are responsible for creating
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+ the final visual output of the application. They are processed in order of their addition/insertion. In our example, the instance of *RenderPass*
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+ is executed first and then the instance of *GlitchPass*. The last enabled pass in the chain is automatically rendered to the screen. The setup
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+ of the passes looks like so:
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+ </p>
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+
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+ <code>
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+ var renderPass = new RenderPass( scene, camera );
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+ composer.addPass( renderPass );
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+
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+ var glitchPass = new GlitchPass();
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+ composer.addPass( glitchPass );
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+ </code>
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+
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+ <p>
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+ *RenderPass* is normally placed at the beginning of the chain in order to provide the rendered scene as an input for the next post-processing step. In our case,
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+ *GlitchPass* is going to use these image data to apply a wild glitch effect. Check out this [link:https://threejs.org/examples/webgl_postprocessing_glitch live example]
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+ to see it in action.
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+ </p>
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+
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+ <h2>Built-in Passes</h2>
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+
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+ <p>
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+ You can use a wide range of pre-defined post-processing passes provided by the engine. They are located in the
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+ [link:https://github.com/mrdoob/three.js/tree/dev/examples/jsm/postprocessing postprocessing] directory.
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+ </p>
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+
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+ <h2>Custom Passes</h2>
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+
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+ <p>
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+ Sometimes you want to write a custom post-processing shader and include it into the chain of post-processing passes. For this scenario,
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+ you can utilize *ShaderPass*. After importing the file and your custom shader, you can use the following code to setup the pass.
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+ </p>
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+
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+ <code>
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+ import { ShaderPass } from 'three/examples/jsm/postprocessing/ShaderPass.js';
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+ import { LuminosityShader } from 'three/examples/jsm/shaders/LuminosityShader.js';
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+
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+ // later in your init routine
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+
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+ var luminosityPass = new ShaderPass( LuminosityShader );
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+ composer.addPass( luminosityPass );
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+ </code>
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+
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+ <p>
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+ The repository provides a file called [link:https://github.com/mrdoob/three.js/blob/master/examples/jsm/shaders/CopyShader.js CopyShader] which is a
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+ good starting code for your own custom shader. *CopyShader* just copies the image contents of the [page:EffectComposer]'s read buffer
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+ to its write buffer without applying any effects.
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+ </p>
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+
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+ </body>
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+</html>
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Mugen87