simple-raytracer/index.html at master · WinterCodeForEverything/simple-raytracer · GitHub

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<html>
<head>
    <title>very simple raytracer</title>
    <script src="3d/Vector3.js"></script>
    <script src="3d/Box.js"></script>
    <script src="3d/Sphere.js"></script>
    <script src="3d/Plane.js"></script>
</head>

<body>

<canvas id="display" width="800" height="600" style="border: 1px solid gray">
</canvas>


</body>


<script>

    var SWIDTH = 800, SHEIGHT=600;

    var DepthShadingDistance = 20;

    var Camera = new Vector3([0,0,-5]);
    var ProjectionPlane = genProjectionPlane(SWIDTH, SHEIGHT);
    var SceneObjects = [];

    var bx = 1.35, by = -3, bz = 3, bsize = 4.5;
    var testobj0 = new BoxAABB(new Vector3([bx, by, bz]), new Vector3([bx+bsize, by+bsize, bz+bsize]), [32,128,200,255]);
    var testobj1 = new Sphere(new Vector3([2.5, 2, 5]), 3);
    var testobj2 = new Sphere(new Vector3([-4, -2, 18]), 10);
    var testobj3 = new Sphere(new Vector3([-2, 0, 6]), 3.3);

    var testPlane = new Plane(new Vector3([0,1,0]), 3.5);

    var lastRayObjMatch = -1;

    testobj2.colour = [0,0,255,255];
    testobj3.colour = [0,255,0,255];

    SceneObjects.push(testobj0);
    SceneObjects.push(testobj1);
    SceneObjects.push(testobj2);
    SceneObjects.push(testobj3);
    SceneObjects.push(testPlane);


    var canvas = document.getElementById('display');
    var context = canvas.getContext('2d');

    var imgdata = context.getImageData(0,0,SWIDTH,SHEIGHT);

    var dx = (ProjectionPlane.xright - ProjectionPlane.xleft) / SWIDTH;
    var dy = (ProjectionPlane.ybottom - ProjectionPlane.ytop) / SHEIGHT;

    var wx, wy;

    wy = ProjectionPlane.ytop;


    var time_start = Date.now();

    for (var y=0; y < SHEIGHT; y++)
    {
        wx = ProjectionPlane.xleft;

        for (var x=0; x < SWIDTH; x++)
        {

            var projPixel = new Vector3([wx, wy, 0]);

            var dir = projPixel.subtract(Camera);
            dir.normalise();

            var Ray = {
                origin: Camera,
                direction: dir
            };

            var result = Raytrace(Ray);//{dist: 0, hit:false};//

            if (result.hit) {
                var col = result.object.colour;

                var scale = 1.1;
                // cheap ass depth-shading
                var shade = result.dist / (DepthShadingDistance*scale);
                //if (shade > 1) shade = 1;
                shade = scale-shade;

                var r = col[0] * shade, g = col[1]*shade, b = col[2] *shade;
                if (r > 255) r=255; if (g > 255) g=255; if (b>255) b=255;
                if (r<0) r=0; if (g<0) g= 0; if (b<0) b=0;
                var a = col[3];
                col = [];

                col[0] = r;
                col[1] = g;
                col[2] = b;
                col[3] = a;


                var rayIntercept = Ray.origin.add(Ray.direction);
                rayIntercept.scale(result.dist);


                if (result.object.getIntersectionCoordinate)
                {
                    var tex = result.object.getIntersectionCoordinate(rayIntercept);
                    var scale = 32;
                    var pattern = (((tex.u * scale) % 1) > 0.5) ^ (((tex.v * scale) % 1) > 0.5);
                    var col2 = [];
                    col2[0] = col[0] * 0.8;
                    col2[1] = col[1] * 0.8;
                    col2[2] = col[2] * 0.8;
                    col2[3] = col[3];

                    var scale2 = Math.max(0, tex.nhit.dot(dir.scale(-1)));
                    col = colourMix(col, col2, pattern);

                    col[0] = Math.floor(col[0] * scale2);
                    col[1] = Math.floor(col[1] * scale2);
                    col[2] = Math.floor(col[2] * scale2);
                    col[3] = 255;

                }


                pset(x, y, col);

            }

            wx += dx;

        }

        wy += dy;
    }


    context.putImageData(imgdata, 0,0);

    var ms = Date.now() - time_start;
    console.log("Render time: "+ms+" ms");

    function colourMix(c1, c2, mix)
    {
        var n = [];

        n[0] = (c1[0] * (1 - mix)) + c2[0] * mix;
        n[1] = (c1[1] * (1 - mix)) + c2[1] * mix;
        n[2] = (c1[2] * (1 - mix)) + c2[2] * mix;
        n[3] = 255;

        return n;
    }


    function Raytrace(ray)
    {
        var tracepoint = {dist: 1000000};
        var newLastRayObjMatch = -2;

        for (var t=0; t<SceneObjects.length; t++)
        {
            var obj = SceneObjects[t];
            var result = obj.intersect(ray);

            if (result.hit == true)
            {
                if (result.dist < tracepoint.dist)
                {
                    tracepoint.hit = true;
                    tracepoint.object = obj;
                    tracepoint.dist = result.dist;
                    newLastRayObjMatch = t;
                }
            }
        }
/*
        below; reorder scene objects so we raytrace our last matched object FIRST on the next ray...
               works but no significant speed improvement doh :/

        if (lastRayObjMatch != newLastRayObjMatch)
        {
            lastRayObjMatch = newLastRayObjMatch;
            var lastObj = SceneObjects.splice(lastRayObjMatch, 1)[0];
            SceneObjects.splice(0,0,lastObj);
        }
        */

        return tracepoint;
    }

    function pset(x,y,c)
    {
        var ofs = y * 4 * SWIDTH + (x*4);
        imgdata.data[ofs+0] = c[0];
        imgdata.data[ofs+1] = c[1];
        imgdata.data[ofs+2] = c[2];
        imgdata.data[ofs+3] = c[3];
    }

    function genProjectionPlane(w, h)
    {
        var uw = w / 100;
        var uh = h / 100;

        var xmin = -(uw/2);
        var xmax = uw/2;
        var ymin = -(uh/2);
        var ymax = uh/2;

        return {xleft:xmin, xright:xmax, ybottom:ymin, ytop:ymax}

    }

</script>


</html>