Advanced Frontend Development

Hong Kong 2015

Hi, my name is...

Edan Kwan

Client work

Personal work/Experiments

Programmable Animation

Animation Flow

get

initial value

update

new value

redraw

finish

if not finished, on next frame...

function loop() {
    // clamp at maximum 60fps in browser
    requestAnimationFrame(loop);
    render();
}

function render() {
    // draw something
}

Lerping - frame-by-frame  animation in a nutshell

function lerp(from, to, ratio) {
    return from + (to - from) * ratio;
}

Easing function by Robert Penner

Choose the one physically makes sense

ease-in-out

ease-in / ease-out

Further Reading: Google Material Design

Choose the cheap one

  • IE opacity
  • Background-color
  • Border-radius
  • Width/Height
  • Webkit-filters

Lazy frame-by-frame easing

var x = 0;

function loop() {
    // x = lerp( x, newX, 0.1 );
    x += ( newX - x ) * 0.1;
}
var tmX = 0;
var tmY = 0;
var mX = 0;
var mY = 0;
var easeRatio = 0.1;
var ball = document.querySelector('.ball');

window.addEventListener('mousemove', onMouseMove);

function onMouseMove(evt) {
    tmX = evt.pageX;
    tmY = evt.pageY;
}

function loop() {
    requestAnimationFrame(loop);
    mX += (tmX - mX) * easeRatio;
    mY += (tmY - mY) * easeRatio;
    ball.style.left = mX + 'px';
    ball.style.top = mY + 'px';
}

loop();

Further Reading: Useful Math Snippets by Howling Moon Software

WebGL

What is WebGL?

WebGL != 3D

WebGL != ThreeJS

  • OpenGL ES 2.0
  • Lower level rendering
  • Experimental(still)

WebGL Shader

Vertex Shader

Fragment Shader

Vertex Shader

JS with WebGL API

var vertices = [x0, y0, x1, y1, x2, y2...]

gl.drawArrays(gl.TRIANGLES, first, count);

// OR draw elements with Indices
gl.drawElements(gl.TRIANGLES, count, type, offset);
attribute vec2 aPosition;

void main(void) {
    gl_Position = vec4(aPosition, 0.0, 1.0);
}

GLSL

  • gl.POINTS
  • gl.LINES
  • gl.LINE_STRIP
  • gl.LINE_LOOP
  • gl.TRIANGLES
  • gl.TRIANGLE_STRIP
  • gl.TRIANGLE_FAN

Fragment Shader

JS with WebGL API

var texture = gl.createTexture();

texture.image = image;

gl.bindTexture(gl.TEXTURE_2D, texture);
uniform sampler2D uTexture;

varying vec2 vTexCoord;

void main() {
    gl_FragColor = texture2D(uTexture, vTexCoord);
}

GLSL

GLSL basis

GLSL Qualifiers

  • attributes
  • uniform
  • varying
  • ...

GLSL data types

  • float
  • bool
  • int
     
  • vec2
  • vec3
  • vec4
  • ivec2/3/4
  • bvec2/3/4
     
  • mat2
  • mat3
  • mat4

Exercises

Graph tools

THANKS!

Advanced Frontend Development (Hong Kong)

By Edan Kwan

Advanced Frontend Development (Hong Kong)

  • 676

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