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gl-renderer

A lightweight webgl renderer.

The underlying Library of glsl-doodle.

Usage

In browser:

<script src="https://unpkg.com/gl-renderer/dist/gl-renderer.js"></script>

With NPM:

npm install gl-renderer

Quick Start

index.frag

#ifdef GL_ES
precision mediump float;
#endif

uniform vec3 color;

void main() {
  gl_FragColor.rgb = color;
  gl_FragColor.a = 1.0;
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Demo</title>
  <script src="https://unpkg.com/gl-renderer/dist/gl-renderer.js"></script>
</head>
<body>
  <canvas id="gl-canvas" width="512" height="512"></canvas>
  <script>
  (async function () {
    const glCanvas = document.getElementById('gl-canvas');
    const renderer = new GlRenderer(glCanvas);

    // load fragment shader and createProgram
    const program = await renderer.load('./index.frag');
    renderer.useProgram(program);

    // set color to RED
    renderer.uniforms.color = [1, 0, 0];

    renderer.render();
  }());
  </script>
</body>
</html>

You will see a canvas 512 pixels wide and 512 pixels high in red.

API Reference

constructor(canvas, options = {})

Create renderer options with specified canvas element and options.

The options:

  • autoUpdate: Force renderer to update when uniforms or meshdata changes. Default value is true.
  • vertexPosition: Attribute name of position in vertex shader. Default value is 'a_vertexPosition'.
  • vertexTextureCoord: Attribute name of texture coordinate in vertext shader. Default value is 'a_vertexTextureCoord'.
  • Other webgl context options: See MDN.
  • webgl2: Use webgl2 context. Default value is false.

renderer.createProgram(fragment[, vertex])

Create a program with specified fragment shader and vertex shader.

const fragmentShader = `
#ifdef GL_ES
precision mediump float;
#endif

void main() {
  gl_FragColor = vec4(1, 0, 0, 1);
}
`;

const program = renderer.createProgram(fragmentShader);
render.useProgram(program);

If you don't specified vertex shader, a default vertex shader will be loaded.

attribute vec4 a_vertexPosition;

void main() {
  gl_PointSize = 1.0;
  gl_Position = a_vertexPosition;
}

or

attribute vec4 a_vertexPosition;
attribute vec2 a_vertexTextureCoord;
varying vec2 vTextureCoord;

void main() {
  gl_PointSize = 1.0;
  gl_Position = a_vertexPosition;
  vTextureCoord = a_vertexTextureCoord;
}

It depends whether you use texture samplers in your fragment shader or not.

async renderer.compile(fragment[, vertex])

gl-render allows you to use #pragma include statment to load and include other shaders.

base.glsl

highp float random(vec2 co) {
    highp float a = 12.9898;
    highp float b = 78.233;
    highp float c = 43758.5453;
    highp float dt= dot(co.xy ,vec2(a,b));
    highp float sn= mod(dt,3.14);
    return fract(sin(sn) * c);
}
const fragmentShader = `
#ifdef GL_ES
precision mediump float;
#endif

#pragma include "./base.glsl"

void main() {
  gl_FragColor = random(gl_FragCoord.xy) * vec4(1, 0, 0, 1);
}
`;

const program = await render.compile(fragmentShader);
renderer.useProgram(program);

async renderer.load(fragmentURL[, vertexURL])

Load fragment shader and vertex shader from url.

const program = await renderer.load('./index.glsl');

renderer.useProgram(program);

renderer.useProgram(program[, attributeDescriptor])

Sets the specified Program as part of the current rendering state.

renderer.createTexture(image)

Wrap a image object (or canvas) to a webgl texture.

function loadImage(src) {
  const img = new Image();
  img.crossOrigin = 'anonymous';
  return new Promise((resolve) => {
    img.onload = function () {
      resolve(img);
    };
    img.src = src;
  });
}

(async function () {
  const glCanvas = document.getElementById('gl-canvas');
  const renderer = new GlRenderer(glCanvas);

  const image = await loadImage('http://path.to.image/image.png');
  const texture = renderer.createTexture(image);

  const program = await renderer.load('./index.frag');
  renderer.useProgram(program);
  // bind texture to samplerMyTex
  renderer.uniforms.samplerMyTex = texture;

  renderer.render();
}());

renderer.loadTexture(src)

Load image from source url and create a texture.

(async function () {
  const glCanvas = document.getElementById('gl-canvas');
  const renderer = new GlRenderer(glCanvas);

  const texture = await renderer.loadTexture('http://path.to.image/image.png');

  const program = await renderer.load('./index.frag');
  renderer.useProgram(program);
  // bind texture to samplerMyTex
  renderer.uniforms.samplerMyTex = texture;

  renderer.render();
}());

renderer.setMeshData(meshData)

Set a list of meshData.

const meshData = [mesh0, mesh1, mesh2...];

A mesh object contains the following properties:

  • positions : Required. The vertex positions of the geometry.
  • cells: Required. The indices of the vertexes.
  • textureCoord: The texture coordinates.
  • attributes: The attributes passed into the shaders.
  • uniforms: The changed uniform values.
  • instanceCount: Set instanceCount for webgl2 context to draw instanced arrays.

index.vert

attribute vec3 a_vertexPosition;
attribute vec3 a_color;

varying vec3 vColor;

void main() {
  gl_PointSize = 1.0;
  gl_Position.xyz = a_vertexPosition;
  gl_Position.w = 1.0;
  vColor = a_color;
}

index.frag

#ifdef GL_ES
precision mediump float;
#endif

varying vec3 vColor;

void main() {
  gl_FragColor = vec4(vColor, 1.0);
}
(async function () {
  const glCanvas = document.getElementById('gl-canvas');
  const renderer = new GlRenderer(glCanvas);

  const program = await renderer.load('./index.frag', './index.vert');
  renderer.useProgram(program, {
    a_color: {
      type: 'UNSIGNED_BYTE',
      normalize: true,
    },
  });

  const vertexColors = [
    [255, 0, 0],
    [255, 0, 0],
    [255, 255, 0],
  ];

  renderer.setMeshData([
    {
      positions: [[-1.0, -1.0, 0.0], [-1.0, 1.0, 0.0], [1.0, 1.0, 0.0]],
      cells: [[0, 1, 2]],
      attributes: {
        a_color: vertexColors,
      },
    },
    {
      positions: [[0.5, 0.5, 0], [-0.5, 0.8, 0], [1, -1, 0]],
      cells: [[0, 1, 2]],
      attributes: {
        a_color: vertexColors,
      },
    },
  ]);

  renderer.render();
}());

renderer.render(clearBuffer = true)

Clear and re-draw canvas. If clearBuffer set to true(default is true), renderer will automately clear color buffer before render.

renderer.uniforms

The uniform declarations in the fragment shader will be automatically bind to renderer.uniforms.

index.frag

#ifdef GL_ES
precision mediump float;
#endif

uniform float u_time;

void main() {
  gl_FragColor = 0.5 * (1.0 + sin(0.00314 * u_time)) * vec4(1, 0, 0, 1);
}
(async function () {
  const glCanvas = document.getElementById('gl-canvas');
  const renderer = new GlRenderer(glCanvas);

  const program = await renderer.load('./index.frag');
  renderer.useProgram(program);

  const startTime = Date.now();

  renderer.uniforms.u_time = 0;

  requestAnimationFrame(function update() {
    renderer.uniforms.u_time = Date.now() - startTime;
    requestAnimationFrame(update);
  });

  renderer.render();
}());

renderer.update()

Cause canvas to clear and re-draw in next frame. Change uniforms or set meshData will force renderer update automatically.