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README.md

webglue

Minimal WebGL wrapper library

webglue is a minimal WebGL wrapper library, which means it provides no abstraction for WebGL concepts such as shaders or geometries.

Instead, webglue provides convinient interface for accessing WebGL.

  • Draw calls are represented using JSON and a tree structure.
  • Shader can be dynamically selected using uniforms and pragma. This is pretty useful since WebGL doesn't support dynamic for clause, dynamic texture lookup, etc.
  • Geometries can be generated using functional programming.

Installation

Run npm install webglue and use it like examples.

Examples

Examples directory

Note that importing should use webglue/lib instead of webglue.

Really minimal example

import Renderer from 'webglue/lib/renderer';
import Camera from 'webglue/lib/camera';
import Transform from 'webglue/lib/transform';
import box from 'webglue/lib/geom/box';
import wireframe from 'webglue/lib/geom/wireframe';

let canvas = document.createElement('canvas');
let gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
let renderer = new Renderer(gl);
document.body.appendChild(canvas);

let camera = new Camera();
camera.transform.translate([0, 0, 5]);
let transform = new Transform();
transform.rotateY(Math.PI / 4);
let geometry = renderer.geometries.create(wireframe(box()));
let shader = renderer.shaders.create(`
attribute vec3 aPosition;

uniform mat4 uProjection;
uniform mat4 uView;
uniform mat4 uModel;

void main() {
  gl_Position = uProjection * uView * uModel * vec4(aPosition, 1.0);
}
`, `
void main() {
  gl_FragColor = vec4(1.0);
}
`);

renderer.render({
  options: {
    clearColor: new Float32Array([0, 0, 0, 1])
  },
  geometry: geometry,
  shader: shader,
  uniforms: {
    uModel: transform.get,
    uView: camera.getView,
    uProjection: camera.getProjection
  }
});

Reference

Renderer

Renderer class contains the WebGL context and all the webglue objects.

In order to render something using webglue, Renderer must be created like this:

import Renderer from 'webglue/lib/renderer';

let canvas = document.createElement('canvas');
let gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
let renderer = new Renderer(gl);
document.body.appendChild(canvas);

Renderer consists of several parts. Each part manages single portion of WebGL resource.

  • shaders
  • geometries
  • textures
  • framebuffers

Renderer itself handles render function.

  • render(passes) - Renders the scene graph.

Scene graph

Scene graph can be false, null, Array, Object, or Function.

  • false and null will be silently ignored.
  • If an array is specified, its contents will be called recursively (array.forEach(this.render)).
  • If an function is specified, the function will be run and returned object will be called recusively (this.render(func())).

An object is treated like a 'scene node', which has WebGL properties and children.

Scene node looks like this:

{
  options: {
    clearColor: '#000000',
    clearDepth: 1,
    cull: gl.BACK,
    depth: gl.LEQUAL
  },
  shader: shader,
  uniforms: {
    uView: camera.getView,
    uProjection: camera.getProjection,
    uColor: '#ff0000',
    uTexture: texture,
    uLightPos: [1, 2, 3],
    uNormal: new Float32Array([1, 2, 3, 4, 5, 6, 7, 8, 9])
  },
  passes: [{
    geometry: geometry,
    uniforms: {
      uModel: transform.get
    }
  }, {
    geometry: geometry2,
    uniforms: {
      uModel: transform2.get
    },
    passes: [{
      framebuffer: {
        framebuffer: framebuffer,
        // Or it can be color: texture2, as 'target' exists for cubemap textures
        color: { texture: texture2, target: gl.TEXTURE_2D }
      }
    }, {
      framebuffer: framebuffer2
    }]
  }]
}

options

options set the WebGL state and features. The following options are available:

  • blend: false | Object (See below)
    • color: Array<Number(0-1)> = [r, g, b, a]
    • equation: WebGLConstant | {rgb: WebGLConstant, alpha: WebGLConstant}
    • func: Array = [sfactor, dfactor] | {rgb: Array, alpha: Array}
  • colorMask: Array
  • depthMask: Boolean
  • clearColor: String | Array<Number(0-1)> = [r, g, b, a]
  • clearDepth: Number
  • clearStencil: Number
  • cull: false | gl.FRONT | gl.BACK | gl.FRONT_AND_BACK | Object (See below)
    • front: gl.CW | gl.CCW
    • face: gl.FRONT | gl.BACK | gl.FRONT_AND_BACK
  • depth: false | gl.NEVER | gl.LESS | gl.EQUAL | gl.LEQUAL | gl.GREATER | gl.NOTEQUAL | gl.GEQUAL | gl.ALWAYS | Object (See below)
    • func: gl.NEVER | gl.LESS | gl.EQUAL | gl.LEQUAL | gl.GREATER | gl.NOTEQUAL | gl.GEQUAL | gl.ALWAYS
    • range: Array<Number(0-1)> = [zNear, zFar]
  • dither: Boolean
  • stencil: false | Object (See below)
    • func: Array = [func, ref, mask] | Array = [front = [func, ref, mask], back = [func, ref, mask]]
    • op: Array = [fail, zFail, pass] | Array = [front = [fail, zFail, pass], back = [fail, zFail, pass]]
  • viewport: false | Array = [x, y, w, h]
  • scissor: false | Array = [x, y, w, h]
  • polygonOffset: false | Array = [factor, units]

shader

shader sets the shader to use. It must be a shader object generated by renderer.shaders.create.

shaderHandler

shaderHandler can be set to override or swap the shader by top node. When children node uses shader, shaderHandler(shader, node, renderer) will be called. The returned value will be used as the shader.

geometry

geometry sets the geometry to use. It must be a geometry object generated by renderer.geometries.create.

framebuffer

framebuffer sets the framebuffer to use. It can be also specified like this to reset bound texture:

framebuffer: {
  framebuffer: framebuffer,
  // Or it can be color: texture2, as 'target' exists for cubemap textures
  color: { texture: texture2, target: gl.TEXTURE_2D }
}

uniforms

Sets uniforms to pass to the shader.

{
  uView: camera.getView,
  uProjection: camera.getProjection,
  uColor: '#ff0000',
  uTexture: texture,
  uLightPos: [1, 2, 3],
  uNormal: new Float32Array([1, 2, 3, 4, 5, 6, 7, 8, 9]),
  uMaterial: {
    ambient: '#ffffff',
    diffuse: '#ff0000',
    specular: '#aabbbbbb' // ARGB
  },
  uArray: ['#ff0000', '#0000ff']
}

This is pretty self-explanatory though, but here's some description:

  • GLSL Structs and arrays will be expanded to support JSON.
  • JS Array will be converted to Float32Array, or Int32Array.
  • RGB can be specified on vec3.
  • RGB or ARGB can be specified on vec4.
  • Texture object can be specified on sampler2D, samplerCube.
  • Function can be specified, then the function's result will be used as the uniform.

passes

Sets the child nodes to render. If this is specified, the node itself won't be rendered - only the children will.

Child node inherits parent node's properties, except clearColor, clearDepth and clearStencil. This is really useful for rendering multiple objects on the screen.

Shader

Shader interface can be accessed using renderer.shaders.

  • create(vert, frag, noPreprocess) - Creates the shader. vert is vertex shader code, frag is fragment shader code.
    If noPreprocess is true, preprocessing will be disabled for the shader.

Shader object

  • dispose() - Disposes the shader object.

Preprocessing

If preprocessing is enabled, webglue will look for registered uniform values, then automatically put #defines into the shader.

#pragma webglue: feature(USE_TEXTURE, uTexture)
#pragma webglue: count(FOR_LOOPS, uLoops, equal)

#ifndef FOR_LOOPS
  #define FOR_LOOPS 0
#endif

precision lowp float;

varying vec2 vTexCoord;
uniform sampler2D uTexture;
uniform vec2 uTextureResolution;

void main() {
  #ifdef USE_TEXTURE
    vec4 sum = texture2D(uTexture, vTexCoord);
    for (int i = 1; i < FOR_LOOPS; ++i) {
      sum += texture2D(uTexture, vTexCoord + uTextureResolution * i);
    }
    gl_FragColor = sum;
  #else
    gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
  #endif
}

webglue-specific pragmas are defined using #pragma webglue: ....

feature

feature(defineName, uniformName)

if uniformName uniform is defined (not false or null or undefined), defineName will be defined.

count

count(defineName, uniformName, governor)

count will automatically change defineName by looking at uniformValue's value, using governor.

governors

Governors can be defined in renderer.shaders.governors.

renderer.shaders.governors.equal = {
  checker: (shader, current) => shader === current,
  allocator: current => current
}

Predefined governors are:

  • max - defined value >= uniform value
  • equal - defined value == uniform value
  • maxLength - defined value >= (uniform value).length

Geometry

Geometry interface can be accessed using renderer.geometries.

  • create(options) - Creates the geometry.
  • createBuffer(data: Float32Array) - Creates the buffer.

Geometry options

Geometry options are defined using the following schema.

{
  attributes: {
    aPosition: {
      data: [0, 0, 0, 0, 0, 1],
      axis: 3
    },
    aInstanced: {
      data: [0, 1],
      axis: 2,
      instanced: 1
    },
    aVerbose: {
      data: [0, 1],
      axis: 1
      // geometry.vbo or buffer object
      // buffer: null
      stride: 4, // Stride value, in bytes
      offset: 0 // Offset value, in bytes
    }
  },
  // Instanced attributes can be defined like this too
  /* instanced: {
    aInstanced: 1
  }, */
  indices: [0, 1],
  mode: gl.LINES,
  // count: 2,
  // primCount: 2
}

Attribute

Attribute name can be anything, but webglue uses aPosition, aTexCoord, aNormal, aTangent by default.

You can use either Float32Array or just regular array, as webglue automatically parses them. It's also possible to define them using 2D array. If using 1D array, you must specify axis.

{
  attributes: {
    aPosition: [
      [0, 0, 0], [1, 0, 0]
    ],
    aTexCoord: {
      data: [0, 0, 1, 1],
      axis: 2
    },
    aNormal: {
      data: new Float32Array([0, 1, 0, 0, 1, 0]),
      axis: 3
    }
  }
}

You can specify WebGL buffer, stride, offset, instanced (divisor) for an attribute too.

Indices

Indices are exactly same as WebGL indices buffer, but an array or 2D array can be used as well.

Mode

Mode is exactly same as WebGL mode, it can be one of the following:

  • gl.TRIANGLES - the default value
  • gl.TRIANGLE_STRIP
  • gl.TRIANGLE_FAN
  • gl.LINES
  • gl.LINE_STRIP
  • gl.LINE_LOOP
  • gl.POINTS

Geometry object

Once renderer.geometries.create(options) is called, it returns a geometry object. It can be used to reuse geometry buffer in another geometry, or to reupload the geometry object.

  • update(options) - Updates the geometry object. Only given attributes/indices will be uploaded (If not specified, it won't be changed.) If null or false is given as an attribute, it'll be deleted.
  • dispose() - Disposes the geometry object. This will remove the VBO object from WebGL, so if other geometry is referencing the geometry, it'll cause an error.

Buffer object

renderer.geometries.createBuffer(data) will return a buffer object. It can be specified in attribute's buffer.

  • update(data) - Reuploads the buffer object.
  • updateSub(data, offset) - Reuploads the portion of buffer object. Offset is in Float32Array index, not in bytes.
  • dispose() - Disposes the buffer object. This will remove the VBO object from WebGL, so if other geometry is referencing the geometry, it'll cause an error.

Texture

Texture interface can be accessed using renderer.textures.

  • create(source, options) - Creates the texture. Source can be a URL, a Image or Video, or TypedArray, or null. If the source is an array (not TypedArray), a cubemap will be created. If TypedArray is specified, width and height must be specified in options.

The following code specifies the default options of textures. If the source is null, minFilter will be gl.LINEAR and mipmap will be disabled.

{
  target: renderer.gl.TEXTURE_2D,
  format: renderer.gl.RGB,
  type: renderer.gl.UNSIGNED_BYTE,
  params: {
    magFilter: gl.LINEAR,
    minFilter: gl.LINEAR_MIPMAP_LINEAR,
    wrapS: gl.CLAMP_TO_EDGE,
    wrapT: gl.CLAMP_TO_EDGE,
    mipmap: true,
    flipY: true
  }
}

Texture object

Once renderer.textures.create(texture, options) is called, it returns a texture object.

  • this.valid - If false, texture will be reuploaded. This is useful for processing videos.
  • this.width - The texture width. (0 if not uploaded)
  • this.height - The texture height. (0 if not uploaded)
  • generateMipmap() - Generates mipmap of the texture.
  • dispose() - Disposes the texture object.

Framebuffer

Framebuffer interface can be accessed using renderer.framebuffers.

  • create(options) - Creates the framebuffer object.

Options look like this. Note that only depth renderbuffer is supported for now.

{
  color: texture,
  depth: gl.DEPTH_COMPONENT16
}

Framebuffer object

renderer.framebuffers.create(options) returns a framebuffer object.

  • readPixels(x, y, width, height, format, type, pixels) - Calls gl.readPixels.
  • readPixelsRGBA(x, y, width, height, pixels) - Reads pixels into pixels.
  • readPixelsRGB(x, y, width, height, pixels) - Reads pixels into pixels.
  • dispose() - Disposes the framebuffer object.
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