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Image Effect Renderer

The image-effect-renderer is a lightweight package that allows you to run fragment shaders in your website using WebGL. It can be used to apply effects to HTML images or video sources. Zero dependencies.

The ImageEffectRenderer supports the most common variables used in Shadertoy and the syntax of fragments shaders from Shadertoy and OneShader. This makes it easy to prototype different effects using Shadertoy or OneShader.

Demo

This is a build from the repository's example/ directory.

Getting started

Installing

Add @mediamonks/image-effect-renderer to your project:

npm i @mediamonks/image-effect-renderer

Basic usage

Simple shader rendering on canvas.

import { ImageEffectRenderer } from '@mediamonks/image-effect-renderer';
import shader from './shader.glsl';

const options = { loop: true };

// Creating an RendererInstance
const renderer = ImageEffectRenderer.createTemporary(wrapperElement, shader, options);

...

// Clean up the renderer when it's no longer needed
ImageEffectRenderer.releaseTemporary(renderer);

ImageEffectRendererOptions

You can set the following options when creating a renderer:

  • loop (boolean) - The renderer will play automatically if set to true. The default value is false.
  • autoResize (boolean) - If set to true, the renderer will automatically resize to fit the wrapperElement. The default value is true.
  • pixelRatio (number) - This sets the pixel ratio of the renderer. The default value is window.devicePixelRatio.
  • useSharedContext (boolean) - If set to true, the renderer will use a shared WebGL context. The default value is false.
  • asyncCompile (boolean) - If set to true, the renderer will compile shaders asynchronously. The default value is true.

ImageEffectRenderers can share one WebGLContext (see useSharedContext). This is needed if multiple ImageEffectRenderers are active at a time. If you have only one ImageEffectRenderer on a page or if you create a large ImageEffectRenderer (i.e. fullscreen), the ImageEffectRenderer will run faster if you create it having its own WebGLContext:

setImage(slotIndex, image, options)

This library allows adding images into up to eight slots, which can be utilized in the shader (as sampler2D iChannel0 to iChannel7). Ensure images are fully loaded before adding them.

  • slotIndex (number) - Index of the slot where the image will be set.
  • image (HTMLImageElement | HTMLCanvasElement | HTMLVideoElement | RendererBuffer) - The image data you want to use in the shader.
  • options (Partial) - Custom configuration for image handling. This is optional.
import { ImageEffectRenderer } from '@mediamonks/image-effect-renderer';
import shader from './shader.glsl';

const renderer = ImageEffectRenderer.createTemporary(wrapperElement, shader, { loop: false });

const imageOptions = {};
renderer.setImage(0, image, imageOptions);
renderer.play();

When setting an image, you can pass an object with the following options:

  • clampX (boolean) - If set to true, the texture's horizontal dimension will be clamped. The default value is true.
  • clampY (boolean) - If set to true, the texture's vertical dimension will be clamped. The default value is true.
  • flipY (boolean) - If set to true, the image texture will be inverted on the y-axis. The default value is false.
  • useMipmap (boolean) - If set to true, mipmaps will be used for texture sampling. The default value is true.
  • useCache (boolean) - If set to true, the texture will be cached. The default value is true.
  • minFilterLinear (boolean) - If set to true, the texture's min filter will be linear. The default value is true.
  • magFilterLinear (boolean) - If set to true, the texture's mag filter will be linear. The default value is true.

play()

Commences or resumes the rendering loop.

renderer.play();

stop()

Pauses the rendering loop.

renderer.stop();

createBuffer(i, shader, options = {})

Creates or replaces a render buffer at a specified index.

  • i (number) - The index of the buffer to create/replace.
  • shader (string) - The shader used for the buffer rendering.
  • options (Partial) - Custom configuration for buffer creation. This is optional.

Returns

  • Renderer - The newly created or replaced buffer object.
let newBuffer = renderer.createBuffer(index, shader, options);

tick(tick: (dt) => void)

Registers a tick function to be called on every frame update.

  • tick (Function) - The function to be called. It accepts a single parameter dt representing the delta time.
renderer.tick(dt => {
    // Operations to be performed every tick
});

ready(ready: () => void)

Registers a ready function to be called when the renderer instance is ready.

  • ready (Function) - The function to be called.
renderer.ready(() => {
    // Operations to be performed when renderer is ready
});

drawFrame(time = 0)

Draws a frame manually.

  • time (number) - Time of the frame to draw. Defaults to 0 if not specified.
renderer.drawFrame(time);

Setting uniforms

You can set uniforms for each RendererInstance (created by calling ImageEffectRenderer.createTemporary or by creating a buffer using renderer.createBuffer).

setUniformFloat(name: string, value: number)

Sets a float uniform in the shader program.

  • name (string) - Name of the uniform.
  • value (number) - Float value.
renderer.setUniformFloat('uniformName', 0.5);

setUniformInt(name: string, value: number)

Sets an integer uniform in the shader program.

  • name (string) - Name of the uniform.
  • value (number) - Integer value.
renderer.setUniformInt('uniformName', 4);

setUniformVec2(name: string, x: number, y: number)

Sets a vec2 uniform in the shader program.

  • name (string) - Name of the uniform.
  • x (number) - X value.
  • y (number) - Y value.
renderer.setUniformVec2('uniformName', 0.5, 1.5);

setUniformVec3(name: string, x: number, y: number, z: number)

Sets a vec3 uniform in the shader program.

  • name (string) - Name of the uniform.
  • x (number) - X value.
  • y (number) - Y value.
  • z (number) - Z value.
renderer.setUniformVec3('uniformName', 0.5, 1.5, 2.5);

setUniformVec4(name: string, x: number, y: number, z: number, w: number)

Sets a vec4 uniform in the shader program.

  • name (string) - Name of the uniform.
  • x (number) - X value.
  • y (number) - Y value.
  • z (number) - Z value.
  • w (number) - W value.
renderer.setUniformVec4('uniformName', 0.5, 1.5, 2.5, 3.5);

setUniformMatrix(name: string, matrix: Float32Array)

Sets a matrix uniform in the shader program.

  • name (string) - Name of the uniform.
  • matrix (Float32Array) - 4X4 matrix.
let matrix = new Float32Array([1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]);
renderer.setUniformMatrix('uniformName', matrix);

Multiple buffers

It is possible to create multiple ping-pong buffers, each functioning with its shader, which functions analogously to adding extra buffer tabs in Shadertoy.

renderer.createBuffer(0, shader);

You can assign a buffer to an image slot:

renderer.buffers[0].setImage(0, this.renderer.buffers[0]); // ping-pong
// and
renderer.setImage(0, renderer.buffers[0]);

A buffer will render in the exact resolution as the output canvas. To see more examples, please take a look at the examples directory.

Building

To build image-effect-renderer, ensure that you have Git and Node.js installed.

Clone a copy of the repo:

git clone https://github.com/mediamonks/image-effect-renderer.git

Change to the image-effect-renderer directory:

cd image-effect-renderer

Install dev dependencies:

npm i

Build package:

npm run build