fragl

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This is a small lib for WebGl shader effects.

• It is not intended for moving vertices or 3d work.
• It is good for creating animated and interactive graphics within fragment shaders and rendering to frame buffers for multiple shader passes and also stacking graphical layers for compositions.

Usage

    // import the fragl lib
    import FraGL from 'FraGL'
 
    // get canvas
    const canvas = document.querySelector('.canvas');
 
    // pass canvas to fragl constructor
    const fragl = new FraGL(args)

So thats the basic setup, contructor args are all optional, if no canvas is given then it will create a canvas element and it will be stored at fragl.domElement

 
    // defautls
    const args = {
        canvas: canvasDomEl, 
        clearColor: [0,0,0,0], 
        imageLoadColor = [255, 150, 150, 255], 
        size:{
            width: window.innerWidth, 
            height: window.innerHeight 
        },
        trasparent: false, 
        premultipliedAlpha: false,         
        antialias: false
        depth: false
    }

• canvas
  • canvas dom el
• clearColor
  • 4 part array (rgba) values between 0 and 1
• imageLoadColor
  • 4 part array (rgba) values between 0 and 255;
• size
  • object of width and height
• trasparent
  • Boolean that indicates if the canvas contains an alpha buffer.
• premultipliedAlpha
  • Boolean that indicates that the page compositor will assume the drawing buffer contains colors with pre-multiplied
• antialias
  • Boolean that indicates whether or not to perform anti-aliasing.
• depth
  • Boolean that indicates that the drawing buffer has a depth buffer of at least 16 bits.

And to resize the FraGL renderer

    fragl.setSize(width,height)

Creating render layers

 
    //.createRenderLayer( 'name'= String, args = Object );
 
    const renderLayer = fragl.createRenderLayer('render-layer', {
        uniforms:{ 
            // dummy uniforms made up for the sake of demonstration
            u_res:{
                value: [ width, height ] // vec2
            },
            u_texture:{
                value: texture // texture
            },
            u_val:{
                value: 1. // float
            }
        },
        vertex:vertexShader, // string
        fragment:fragmentShader // string
    })

Updating uniforms

    renderLayer.uniforms['u_res'].value = [ width, height ]

Create a texture from an image

    const texture = fragl.textureFromImage('./path/to/image.jpg');

Creating render texture

    const renderTexture = fragl.createRenderTexture({
        width: window.innerWidth,
        height: window.innerHeight
    });
 
    renderLayer.uniforms['u_texture'].value = renderTexture.texture

and to resize

    renderTexture.setSize(w,h)

Rendering

    // render to canvas
    renderLayer.render()
 
    // render to renderTexture
    renderLayer.render(renderTexture)

an example

    render(){
        renderLayer1.render(renderTexture)
 
        renderLayer2.uniforms['u_texure'].value = renderTexture.texture
 
        renderLayer2.render()
    }

Vertex Shader

Something like this should be the base for your vertex shader

precision highp float;
attribute vec2 a_position;
attribute vec2 a_texcoord;
 
varying vec2 vUv;
 
void main() {
    vUv = a_texcoord;
    gl_Position = vec4(a_position, 0, 1);;
}