@mgx/engine1
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0.2.2 • Public • Published

@mgx/engine1

Very basic WebGL engine. Does as good as no abstraction - only intended to make the whole WebGL API a little less verbose.

Installation

npm i @mgx/engine1

Example usage

This demo draws a few moving cubes and adds some blur on top of them.

import { bindTextureToFramebuffer, createEmptyTexture, createFramebuffer, FramebufferObject } from '../src/webgl';
import { Context, InstancedElementsBundle, Index, Program, AttributeData,
    ElementsBundle, InstancedAttributeData, UniformData, ArrayBundle, TextureData } from '../src/engine.core';
import { boxE, gaussianKernel, rectangleA } from '../../utils/shapes';
import { projectionMatrix, identityMatrix, matrixMultiplyList, rotateXMatrix,
    rotateYMatrix, rotateZMatrix, translateMatrix, transposeMatrix, flatten2, flatten3 } from '../../utils/math';
import { renderLoop } from '../../utils/general';



const body = document.getElementById('container') as HTMLDivElement;
const canvas = document.getElementById('canvas') as HTMLCanvasElement;
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
const gl = canvas.getContext('webgl') as WebGLRenderingContext;
if (!gl) {
    throw new Error('no context');
}

const box = boxE(0.25, 0.25, 0.25);



const nrInstances = 4;

let transformMatrices = [
    transposeMatrix(translateMatrix(-0.5,  0.5, -3.5)),
    transposeMatrix(translateMatrix( 0.5,  0.5, -2.5)),
    transposeMatrix(translateMatrix( 0.5, -0.5, -1.5)),
    transposeMatrix(translateMatrix(-0.5, -0.5, -0.5)),
];

let colors = [
    [1.0, 0.0, 0.0, 1.0],
    [0.0, 1.0, 0.0, 1.0],
    [0.0, 0.0, 1.0, 1.0],
    [1.0, 1.0, 0.0, 1.0],
];

const projection = transposeMatrix(projectionMatrix(Math.PI / 2, 1, 0.01, 100));

const context = new Context(gl, true);

const drawingBundle = new InstancedElementsBundle(new Program(`
    precision mediump float;
    attribute vec4 a_position;
    attribute mat4 a_transform;
    attribute vec4 a_color;
    varying vec4 v_color;
    uniform mat4 u_projection;
    void main() {
        vec4 pos = u_projection * a_transform * a_position;
        gl_Position = pos;
        v_color = a_color;
    }
`, `
    precision mediump float;
    varying vec4 v_color;
    void main() {
        gl_FragColor = v_color;
    }
`), {
    'a_position': new AttributeData(new Float32Array(flatten2(box.vertices)), 'vec4', false),
    'a_transform': new InstancedAttributeData(new Float32Array(flatten3(transformMatrices)), 'mat4', true, 1),
    'a_color': new InstancedAttributeData(new Float32Array(flatten2(colors)), 'vec4', false, 1)
}, {
    'u_projection': new UniformData('mat4', flatten2(projection))
}, {},
'triangles',
new Index(new Uint16Array(flatten2(box.vertexIndices))), nrInstances);


const fb = createFramebuffer(gl);
const fbTexture = createEmptyTexture(gl, canvas.width, canvas.height);
const fbo = bindTextureToFramebuffer(gl, fbTexture, fb);




const blurBundle = new ArrayBundle(new Program(`
    precision mediump float;
    attribute vec4 a_position;
    attribute vec2 a_texPosition;
    varying vec2 v_texPosition;
    void main() {
        gl_Position = a_position;
        v_texPosition = a_texPosition;
    }
`, `
    precision mediump float;
    uniform sampler2D u_texture;
    uniform vec2 u_textureSize;
    uniform mat3 u_blur;
    varying vec2 v_texPosition;
    void main() {
        float deltaX = 7.0 / u_textureSize[0];
        float deltaY = 7.0 / u_textureSize[1];
        vec4 color = texture2D(u_texture, v_texPosition + vec2(-deltaX,  deltaY)) * u_blur[0][0]
                   + texture2D(u_texture, v_texPosition + vec2(      0,  deltaY)) * u_blur[1][0]
                   + texture2D(u_texture, v_texPosition + vec2( deltaX,  deltaY)) * u_blur[2][0]
                   + texture2D(u_texture, v_texPosition + vec2(-deltaX,       0)) * u_blur[0][1]
                   + texture2D(u_texture, v_texPosition + vec2(      0,       0)) * u_blur[1][1]
                   + texture2D(u_texture, v_texPosition + vec2( deltaX,       0)) * u_blur[2][1]
                   + texture2D(u_texture, v_texPosition + vec2(-deltaX, -deltaY)) * u_blur[0][2]
                   + texture2D(u_texture, v_texPosition + vec2(      0, -deltaY)) * u_blur[1][2]
                   + texture2D(u_texture, v_texPosition + vec2( deltaX, -deltaY)) * u_blur[2][2];
        gl_FragColor = color;
    }
`), {
    'a_position': new AttributeData(new Float32Array(flatten2(rectangleA(2, 2).vertices)), 'vec4', false),
    'a_texPosition': new AttributeData(new Float32Array(flatten2(rectangleA(2, 2).texturePositions)), 'vec2', false),
}, {
    'u_blur': new UniformData('mat3', flatten2(transposeMatrix(gaussianKernel()))),
    'u_textureSize': new UniformData('vec2', [fbo.width, fbo.height])
}, {
    'u_texture': new TextureData(fbo.texture)
}, 'triangles', 6);






drawingBundle.upload(context);
drawingBundle.initVertexArray(context);
blurBundle.upload(context);
blurBundle.initVertexArray(context);

let time = 0;
renderLoop(60, (tDelta: number) => {
    time += tDelta;

    drawingBundle.bind(context);
    transformMatrices = [
        transposeMatrix(matrixMultiplyList([  translateMatrix(-1.0,  0.8, 0.5 * Math.sin(time * 0.003) + -3.5), rotateXMatrix(time * 0.1), ])),
        transposeMatrix(matrixMultiplyList([  translateMatrix( 0.5,  0.5, 1.0 * Math.sin(time * 0.005) + -2.5), rotateYMatrix(time * 0.1), ])),
        transposeMatrix(matrixMultiplyList([  translateMatrix( 0.5, -0.5, 0.5 * Math.sin(time * 0.003) + -1.5), rotateZMatrix(time * 0.1), ])),
        transposeMatrix(matrixMultiplyList([  translateMatrix(-0.2, -0.2, 1.0 * Math.sin(time * 0.003) + -1.5), rotateXMatrix(time * 0.1), ])),
    ];
    drawingBundle.updateAttributeData(context, 'a_transform', new Float32Array(flatten3(transformMatrices)));
    drawingBundle.draw(context, [0, 0, 0, 0], fbo);

    blurBundle.bind(context);
    blurBundle.draw(context);
});

Important classes

  • Program: Container for a WebGLProgram - contains the vertex- and the fragment-shader-code.
  • Bundle: Container for a Program together with all related attribute-, uniform-, and texture-data. Handles uploading of all data to the GPU, the binding of that data to the right slots, and the actual rendering.
    • ArrayBundle: Use this type of bundle for gl.drawArrays-style drawing. Simple, but requires you to keep multiple copies of a vertex if the vertex forms part of more than one triangle.
    • ElementsBundle: Use this type of bundle for gl.drawElements-style drawing. Instead of duplicating vertices that are used in multiple objects (like ArrayBundle does), it relies on an Index to tell the GPU which vertex to pick next. This way, the GPU doesn't loop a single time through the array of given vertices, but jumps around according to the index. A bit more memory-efficient.
    • InstancedArrayBundle: Like ArrayBundle, but for drawArraysInstancedANGLE-style drawing. Loops through the given vertices nrInstances times. Efficient when you want to draw many instances of the same object, such as hundreds of trees, only with variations in location. Expects every instanced attribute to contain nrInstances times as many values. That is, when using an instanced attribute mat4 and nrInstances=3, requires you to pass in the data for 3 mat4-matrices (so, 3 * 16 = 48 values). Use ordinary AttributeData for data that doesn't change between instances, and InstancedAttributeData for data that does.
    • InstancedElementsBundle: Like ElementsBundle, but for drawElementsInstancedANGLE-style drawing. Loops through the given vertices nrInstances times. Efficient when you want to draw many instances of the same object, such as hundreds of trees, only with variations in location. Expects every instanced attribute to contain nrInstances times as many values. That is, when using an instanced attribute mat4 and nrInstances=3, requires you to pass in the data for 3 mat4-matrices (so, 3 * 16 = 48 values). Use ordinary AttributeData for data that doesn't change between instances, and InstancedAttributeData for data that does.
  • IAttributeData
    • AttributeData: Container for attribute-data. A copy of the data is kept locally even after uploading the data to the GPU, so that it can later be re-uploaded, if required.
    • InstancedAttributeData: Like AttributeData, but expects there to be nrInstances times as many values. That is, for a vec2 with nrInstances=4, you'd pass 4 * 2 = 8 values. Can only be used in an InstancedArrayBundle or an InstancedElementsBundle.
  • UniformData: Container for uniform-data. A copy of the data is kept locally even after uploading the data to the GPU, so that it can later be re-uploaded, if required.
  • TextureData: Container for texture-data. A copy of the data is kept locally even after uploading the data to the GPU, so that it can later be re-uploaded, if required.
  • FramebufferObject: Every bundle can optionally render to a framebuffer instead of to the canvas. This way, the data now inside the framebuffer can be used as the input for another shader.

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Install

npm i @mgx/engine1

Weekly Downloads

1

Version

0.2.2

License

Apache-2.0

Unpacked Size

409 kB

Total Files

25

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Collaborators

  • michaellangbein