webgl_helper 0.3.0

A helper library for the WebGL API

webgl_helper

A small helper library to reduce boilerplate code when using the WebGL API.

Features

The development of this library has just started. Many features are not completely implemented yet or missing at all.

• Reduces boilerplate code, e.g. connecting buffers to vertex attrib locations and draw in 1 call.
• Makes the WebGL API more type safe by adding types for a number of WebGL constants.
• Provides some helper functions, e.g. for create a projection or camera matrix.

This library is not a high level library like three.js.

Example

Here is a small example for using this library:

import 'dart:html';
import 'package:webgl_helper/webgl_helper.dart';

ShaderProgram program;
Buffer buffer;

main() {
  // query the canvas element
  var canvasElement = querySelector('#webgl-canvas');

  // init the webgl rendering context
  glInit(canvasElement);

  // set the color used to clear the color buffer
  glClearColor(0, 0, 0, 1);

  // enable blending and set the blend function
  glEnableBlend(true);
  glBlendFunc(BlendingCoefficient.SRC_ALPHA, BlendingCoefficient.ONE_MINUS_SRC_ALPHA);

  // create a shader program
  program = new ShaderProgram.fromSources(vertexShader, fragmentShader);

  // create a buffer that contains 2 types of per vertex data: positions and colors
  buffer = new Buffer(BufferTarget.ARRAY_BUFFER);
  buffer.data({
    'a_position': {
      Buffer.SIZE: 2, // 2 components per vertex (x, y)
      Buffer.DATA: [1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, -1.0]
    },
    'a_color': {
      Buffer.SIZE: 3, // 3 components per vertex (r, g, b)
      Buffer.DATA: [1.0, 1.0, 1.0, 0.0, 1.0, 1.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0]
    }
  });

  // start rendering
  window.requestAnimationFrame(render);
}

render(tick) {
  // clear the color buffer
  glClear([ClearMode.COLOR_BUFFER]);

  // draw the vertices using the given shader program and the vertex data stored in the buffer. additionally, set an
  // uniform.
  gluDrawArrays(program, buffer, uniformSetters: {
    'u_alpha': (uniform) => uniform.set1f(0.5)
  });

  // next frame
  window.requestAnimationFrame(render);
}

// the vertex shader...
final vertexShader = '''
#version 100

precision mediump float;

attribute vec2 a_position;
attribute vec3 a_color;
varying vec3 v_color;

void main() {
  v_color = a_color;
  gl_Position = vec4(a_position / 2.0, 0.0, 1.0);
}
''';

// ...and the fragment shader
final fragmentShader = '''
#version 100

precision mediump float;

uniform float u_alpha;
varying vec3 v_color;

void main() {
  gl_FragColor = vec4(v_color, u_alpha);
}
''';