glsl-quad

glsl-quad

Description

glsl-quad provides simple utilities (simple quad mesh, shaders, etc.) for image processing with webgl.

See glsl-quad-demo.js for usage.

Dependencies

• nodejs
• browserify
• regl (for demo)
• resl (for demo)
• budo (for quick demo as an alternative to running browserify)

Demo

To run the demo, run:

    cd ./glsl-quad
    
    #install npm dependencies
    npm install
    
    #browser should open with the demo
    budo glsl-quad-demo.js --open

Results:

branch	demo
master	glsl-quad-demo

    | [glsl-quad-uv-demo](https://realazthat.github.io/glsl-quad/master/www/glsl-quad-uv-demo/index.html)
    | [glsl-quad-pos-demo](https://realazthat.github.io/glsl-quad/master/www/glsl-quad-pos-demo/index.html)
    | [glsl-quad-vertical-flip-tests](https://realazthat.github.io/glsl-quad/master/www/glsl-quad-vertical-flip-tests/index.html)

develop | glsl-quad-demo | glsl-quad-uv-demo | glsl-quad-pos-demo | glsl-quad-vertical-flip-tests

Docs

const quad = require('./glsl-quad.js');

quad.verts

• A list of vertices that can be used for webgl positions, that make up a quad (two triangles).

quad.indices

• A list of indices that can be used for webgl triangles, that make up a quad (two triangles).

quad.uvs

• A list of uv attributes for the vertices.

quad.shader.frag

• Returns the webgl 1.0 fragment shader to use.
• The fragment shader expects a uniform shader (sampler2D) named u_tex.

quad.shader.vert

• Returns the webgl 1.0 vertex shader to use.
• The vertex shader expects:
  • A uniform float named u_clip_y, representing whether to flip the y-axis; values of 1 or -1.
  • An attribute list of vec2 positions of the vertices named a_position.
  • An attribute list of vec2 uvs of the vertices named a_uv.

quad.bitmaps.directions.uri

• Returns a data uri for an image that can be used to test proper display directions.
• Can see the images in the glsl-quad/assets/ directory.

Usage

See glsl-quad-demo.js for a full demo using regl and resl.

An excerpt:

    const drawTexture = regl({
      frag: quad.shader.frag,
      vert: quad.shader.vert,
      attributes: {
        a_position: quad.verts,
        a_uv: quad.uvs
      },
      elements: quad.indices,
      uniforms: {
        u_tex: regl.prop('texture'),
        u_clip_y: 1
      }
    });

    drawTexture({texture});