// Simmering gold particle test
// Original particle idea from https://github.com/sebleedelisle/live-coding-presentations
var canvas = document.createElement('canvas'),
    ctx = canvas.getContext('2d'),
    screenW = window.innerWidth,
    screenH = window.innerHeight,
    mouseX = screenW / 2,
    mouseY = screenH / 2,
    mouseVelX = 0,
    mouseVelY = 0,
    lastMouseX = mouseX,
    lastMouseY = mouseY,
    mouseDown = false,
    particles = [],
    MAX_PARTICLES = 350,
    particleImage = new Image();

particleImage.src = 'data:image/png;base64,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'; 

var requestAnimFrame = function() {
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback) {
        window.setTimeout(callback, 1000 / 60);
    };
}();

// Functions
function init() {
    document.body.appendChild(canvas);
    canvas.width = screenW;
    canvas.height = screenH;
    initMouseListeners();
    executeLoop();// Start
}
function executeLoop() {
    loop();
    requestAnimFrame(executeLoop);
}
function loop() {
    mouseVelX = mouseX - lastMouseX;
    mouseVelY = mouseY - lastMouseY;
    lastMouseX = mouseX;
    lastMouseY = mouseY;
    makeParticle(4);
    ctx.fillStyle = "rgba(0,0,0,0.9)";
    ctx.fillRect(0, 0, screenW, screenH);

    for (var i = 0, len = particles.length; i < len; i++) {
        var particle = particles[i];
        // Bottom wall
        if(particle.posY > screenH - 170) {
            particle.velY *= -0.8; 
            particle.posY = screenH - 170;
        }
        // Left wall
        if(particle.posX < 0) {
            particle.velX *= -0.8; 
            particle.posX = 0;
        }
        // Right wall
        if(particle.posX > screenW) {
            particle.velX *= -0.8; 
            particle.posX = screenW;
        }
        particle.update();
        particle.render(ctx);
    }
    while (particles.length > MAX_PARTICLES) {
        particles.shift();
    }
}
function makeParticle(particleCount) {
    for(var i = 0; i < particleCount; i++) {
        var particle = new ImageParticle(particleImage, mouseX, mouseY);
        particle.velX = randomRange(-5,5) + (mouseVelX * 0.4) ;
        particle.velY = randomRange(-5,5) + (mouseVelY * 0.4) ;
        particle.size = randomRange(2,11);
        if (mouseDown === true) {
            particle.size = randomRange(1,6);
            particle.drag = 1.1;
        }
        particles.push(particle);
    }
}
function initMouseListeners() {
    document.addEventListener('mousemove', handleMouseMove, false);
    document.addEventListener('touchmove', handleTouchMove, false);
    document.addEventListener('mousedown', handleMouseDown, false);
    document.addEventListener('mouseup', handleMouseUp, false);
}
function handleMouseMove(event) {
    event.preventDefault();
    mouseX = event.clientX;
    mouseY = event.clientY;
}
function handleTouchMove(event) {
    event.preventDefault();
    mouseX = event.changedTouches[0].clientX;
    mouseY = event.changedTouches[0].clientY;
}
function handleMouseDown(event) {
    mouseDown = true;
}
function handleMouseUp(event) {
    mouseDown = false;
}
function randomRange(min, max) {
    return ((Math.random()*(max-min)) + min);
}

// Class ImageParticle
// Copyright (c)2010-2013, Seb Lee-Delisle, seb.ly
// All rights reserved.
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
function ImageParticle(img, posx, posy) {
    this.posX = posx;
    this.posY = posy;
    this.velX = 0;
    this.velY = 0;
    this.shrink = 0.96;
    this.size = 1;
    this.maxSize = -1;
    this.shimmer = true;
    this.drag = 0.98;
    this.gravity = 0.2;
    this.alpha = 1;
    this.fade = 0;
    this.spin = 0;
    this.rotation = 0;
    this.compositeOperation = 'lighter';
    this.img = img;
    this.update = function() {
        this.velX *= this.drag;
        this.velY *= this.drag;
        this.velY += this.gravity;
        this.posX += this.velX;
        this.posY += this.velY;
        this.size *= this.shrink;
        if((this.maxSize > 0) && (this.size > this.maxSize)) this.size = this.maxSize;
        this.alpha -= this.fade;
        if(this.alpha < 0) this.alpha = 0;
        this.rotation += this.spin;
    };
    this.render = function(c) {
        if(this.alpha === 0) return;
        c.save();
        c.translate(this.posX, this.posY);
        var s = this.shimmer ? this.size * Math.random() : this.size;
        c.scale(s, s);
        c.rotate(this.rotation * Math.PI / 180);
        c.translate(img.width * -0.5, img.width * -0.5);
        c.globalAlpha = this.alpha;
        c.globalCompositeOperation = this.compositeOperation;
        c.drawImage(img, 0, 0);
        c.restore();
    };
}

init();