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3D Cube images Slideshow with HTML5

Created about a year ago   Views 43529   downloads 7841    Author script-tutorials
3D Cube images Slideshow with HTML5
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Our new tutorial tells us about creation of animated 3D Cube slideshow (pictures are located within the walls of the cube). The cube itself rotates continuously.

Step 1. HTML

This is markup of our result slideshow page. Here it is.

index.html

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <title>HTML5 3D Cube Slideshow | Script Tutorials</title>
        <link href="css/main.css" rel="stylesheet" type="text/css" />
        <script src="js/script.js"></script>
    </head>
    <body>
        <canvas id="slideshow" width="1280" height="800"></canvas>
    </body>
</html>

Step 2. CSS

css/main.css

That file available in package (because it just contains styles of page layout)

Step 3. JS

js/script.js

var canvas, ctx;
var aImages = [];
var points = [];
var triangles = [];
var textureWidth, textureHeight;
var lev = 3;
var angle = 0;

// scene vertices
var vertices = [
    new Point3D(-2,-1,2),
    new Point3D(2,-1,2),
    new Point3D(2,1,2),
    new Point3D(-2,1,2),
    new Point3D(-2,-1,-2),
    new Point3D(2,-1,-2),
    new Point3D(2,1,-2),
    new Point3D(-2,1,-2)
];

// scene faces (6 faces)
var faces  = [[0,1,2,3],[1,5,6,2],[5,4,7,6],[4,0,3,7],[0,4,5,1],[3,2,6,7]];

function Point3D(x,y,z) {
    this.x = x;
    this.y = y;
    this.z = z;

    this.rotateX = function(angle) {
        var rad, cosa, sina, y, z
        rad = angle * Math.PI / 180
        cosa = Math.cos(rad)
        sina = Math.sin(rad)
        y = this.y * cosa - this.z * sina
        z = this.y * sina + this.z * cosa
        return new Point3D(this.x, y, z)
    }
    this.rotateY = function(angle) {
        var rad, cosa, sina, x, z
        rad = angle * Math.PI / 180
        cosa = Math.cos(rad)
        sina = Math.sin(rad)
        z = this.z * cosa - this.x * sina
        x = this.z * sina + this.x * cosa
        return new Point3D(x,this.y, z)
    }
    this.rotateZ = function(angle) {
        var rad, cosa, sina, x, y
        rad = angle * Math.PI / 180
        cosa = Math.cos(rad)
        sina = Math.sin(rad)
        x = this.x * cosa - this.y * sina
        y = this.x * sina + this.y * cosa
        return new Point3D(x, y, this.z)
    }
    this.projection = function(viewWidth, viewHeight, fov, viewDistance) {
        var factor, x, y
        factor = fov / (viewDistance + this.z)
        x = this.x * factor + viewWidth / 2
        y = this.y * factor + viewHeight / 2
        return new Point3D(x, y, this.z)
    }
}

// array of photos
var aImgs = [
    'images/pic1.jpg',
    'images/pic2.jpg',
    'images/pic3.jpg',
    'images/pic4.jpg'
];
for (var i = 0; i < aImgs.length; i++) {
    var oImg = new Image();
    oImg.src = aImgs[i];
    aImages.push(oImg);

    oImg.onload = function () {
        textureWidth = oImg.width;
        textureHeight = oImg.height;
    }
}

window.onload = function(){
    // creating canvas objects
    canvas = document.getElementById('slideshow');
    ctx = canvas.getContext('2d');

    // prepare points
    for (var i = 0; i <= lev; i++) {
        for (var j = 0; j <= lev; j++) {
            var tx = (i * (textureWidth / lev));
            var ty = (j * (textureHeight / lev));
            points.push({
                tx: tx,
                ty: ty,
                nx: tx / textureWidth,
                ny: ty / textureHeight,
                ox: i,
                oy: j
            });
        }
    }

    // prepare triangles ----
    var levT = lev + 1;
    for (var i = 0; i < lev; i++) {
        for (var j = 0; j < lev; j++) {
            triangles.push({
                p0: points[j + i * levT],
                p1: points[j + i * levT + 1],
                p2: points[j + (i + 1) * levT],
                up: true
            });
            triangles.push({
                p0: points[j + (i + 1) * levT + 1],
                p1: points[j + (i + 1) * levT],
                p2: points[j + i * levT + 1],
                up: false
            });
        }
    }

    drawScene();
};

function drawScene() {
    // clear context
    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);

    // rotate scene
    var t = new Array();
    for (var iv = 0; iv < vertices.length; iv++) {
        var v = vertices[iv];
        var r = v.rotateY(angle);
        //var r = v.rotateX(angle).rotateY(angle);
        var prj = r.projection(ctx.canvas.width, ctx.canvas.height, 1000, 3);
        t.push(prj)
    }

    var avg_z = new Array();
    for (var i = 0; i < faces.length; i++) {
        var f = faces[i];
        avg_z[i] = {"ind":i, "z":(t[f[0]].z + t[f[1]].z + t[f[2]].z + t[f[3]].z) / 4.0};
    }

    // get around through all faces
    for (var i = 0; i < faces.length; i++) {
        var f = faces[avg_z[i].ind];

        if (t[f[3]].z+t[f[2]].z+t[f[1]].z+t[f[0]].z > -3) {
            ctx.save();

            // draw surfaces
            ctx.fillStyle = "rgb(160,180,160)";
            ctx.beginPath();
            ctx.moveTo(t[f[0]].x,t[f[0]].y);
            ctx.lineTo(t[f[1]].x,t[f[1]].y);
            ctx.lineTo(t[f[2]].x,t[f[2]].y);
            ctx.lineTo(t[f[3]].x,t[f[3]].y);
            ctx.closePath();
            ctx.fill();

            // draw stretched images
            if (i < 4) {
                var ip = points.length;
                while (--ip > -1) {
                    var p = points[ip];
                    var mx = t[f[0]].x + p.ny * (t[f[3]].x - t[f[0]].x);
                    var my = t[f[0]].y + p.ny * (t[f[3]].y - t[f[0]].y);
                    p.px = (mx + p.nx * (t[f[1]].x + p.ny * (t[f[2]].x - t[f[1]].x) - mx)) + p.ox;
                    p.py = (my + p.nx * (t[f[1]].y + p.ny * (t[f[2]].y - t[f[1]].y) - my)) + p.oy;
                }

                var n = triangles.length;
                while (--n > -1) {
                    var tri = triangles[n];
                    var p0 = tri.p0;
                    var p1 = tri.p1;
                    var p2 = tri.p2;

                    var xc = (p0.px + p1.px + p2.px) / 3;
                    var yc = (p0.py + p1.py + p2.py) / 3;

                    ctx.save();
                    ctx.beginPath();
                    ctx.moveTo((1.05 * p0.px - xc * 0.05), (1.05 * p0.py - yc * 0.05));
                    ctx.lineTo((1.05 * p1.px - xc * 0.05), (1.05 * p1.py - yc * 0.05));
                    ctx.lineTo((1.05 * p2.px - xc * 0.05), (1.05 * p2.py - yc * 0.05));
                    ctx.closePath();
                    ctx.clip();

                    // transformation
                    var d = p0.tx * (p2.ty - p1.ty) - p1.tx * p2.ty + p2.tx * p1.ty + (p1.tx - p2.tx) * p0.ty;
                    ctx.transform(
                        -(p0.ty * (p2.px - p1.px) -  p1.ty * p2.px  + p2.ty *  p1.px + (p1.ty - p2.ty) * p0.px) / d, // m11
                         (p1.ty *  p2.py + p0.ty  * (p1.py - p2.py) - p2.ty *  p1.py + (p2.ty - p1.ty) * p0.py) / d, // m12
                         (p0.tx * (p2.px - p1.px) -  p1.tx * p2.px  + p2.tx *  p1.px + (p1.tx - p2.tx) * p0.px) / d, // m21
                        -(p1.tx *  p2.py + p0.tx  * (p1.py - p2.py) - p2.tx *  p1.py + (p2.tx - p1.tx) * p0.py) / d, // m22
                         (p0.tx * (p2.ty * p1.px  -  p1.ty * p2.px) + p0.ty * (p1.tx *  p2.px - p2.tx  * p1.px) + (p2.tx * p1.ty - p1.tx * p2.ty) * p0.px) / d, // dx
                         (p0.tx * (p2.ty * p1.py  -  p1.ty * p2.py) + p0.ty * (p1.tx *  p2.py - p2.tx  * p1.py) + (p2.tx * p1.ty - p1.tx * p2.ty) * p0.py) / d  // dy
                    );
                    ctx.drawImage(aImages[i], 0, 0);
                    ctx.restore();
                }
            }
        }
    }

    // shift angle and redraw scene
    angle += 0.3;
    setTimeout(drawScene, 40);
}

The article source:http://www.script-tutorials.com/html5-3d-cube-slideshow/