pardo · March 10, 2017 11:44
diff --git a/index.html b/index.html
 <html>
    <head>
        <style>
            body, html {
                margin: 0;
                padding: 0;
                height: 100vh;
                width: 100vw;
                overflow: none;
            }
            canvas {
            }
        </style>
   </head>
    <body>
        <canvas id="land"></canvas>
    </body>
    <script src="main.js" type="application/javascript"></script> 
 </html>
diff --git a/main.js b/main.js
 // Iterative midpoint vertical displacement
 function locationOf(element, array, comparer, start, end) {
    if (array.length === 0)
        return -1;

    start = start || 0;
    end = end || array.length;
    var pivot = (start + end) >> 1;  // should be faster than the above calculation

    var c = comparer(element, array[pivot]);
    if (end - start <= 1) return c == -1 ? pivot - 1 : pivot;

    switch (c) {
        case -1: return locationOf(element, array, comparer, start, pivot);
        case 0: return pivot;
        case 1: return locationOf(element, array, comparer, pivot, end);
    };
 };

 // sample for objects like {lastName: 'Miller', ...}
 var cmpPoint = function (a, b) {
    if (a[0] < b[0]) return -1;
    if (a[0] > b[0]) return 1;
    return 0;
 }

 Array.prototype.insertOrdered = function (element, cmp) {
    var array = this.slice();
    array.splice(locationOf(element, array, cmp) + 1, 0, element);
    return array;
 };


 function midpoint_displacement(start, end, roughness, vertical_displacement, num_of_iterations){
    /*
    Given a straight line segment specified by a starting point and an endpoint
    in the form of [starting_point_x, starting_point_y] and [endpoint_x, endpoint_y],
    a roughness value > 0, an initial vertical displacement and a number of
    iterations > 0 applies the  midpoint algorithm to the specified segment and
    returns the obtained list of points in the form
    points = [[x_0, y_0],[x_1, y_1],...,[x_n, y_n]]
    */

    if (!num_of_iterations) { num_of_iterations = 16 }
    // Final number of points = (2^iterations)+1
    if (vertical_displacement == null) {
        // if no initial displacement is specified set displacement to:
        // (y_start+y_end)/2
        vertical_displacement = (start[1]+end[1])/2
    }
    // Data structure that stores the points is a list of lists where
    // each sublist represents a point and holds its x and y coordinates:
    // points=[[x_0, y_0],[x_1, y_1],...,[x_n, y_n]]
    //             |          |              |
    //           point 0    point 1        point n
    // The points list is always kept sorted from smallest to biggest x-value
    var points = [start, end];
    var iteration = 1;
    while( iteration <= num_of_iterations ){
        // Since the list of points will be dynamically updated with the new computed
        // points after each midpoint displacement it is necessary to create a copy
        // of the state at the beginning of the iteration so we can iterate over
        // the original sequence.
        // Tuple type is used for security reasons since they are immutable in Python.
        
        var points_tup = points.slice();
        for (var i=0; i<points_tup.length-1; i++) {
            // Calculate x and y midpoint coordinates:
            var midpoint = [
                (points_tup[i][0]+points_tup[i+1][0])/2,
                (points_tup[i][1]+points_tup[i+1][1])/2
            ];
            // Displace midpoint y-coordinate
            midpoint[1] += (Math.random()> 0.5)?-vertical_displacement:vertical_displacement;
            // Insert the displaced midpoint in the current list of points
            points = points.insertOrdered(midpoint, cmpPoint);
        }            
        // Reduce displacement range
        vertical_displacement *= 2 ** (-roughness)
        // update number of iterations
        iteration += 1
    }
        
    return points
 }


 function draw(points, color, clear) {
    var canvas = document.getElementById('land');
    var c2 = canvas.getContext('2d');

    if (clear) {
        c2.clearRect(0, 0, canvas.width, canvas.height);
    }
    c2.fillStyle = color;
    
    c2.beginPath();
    c2.moveTo(0, canvas.height);
    for (var i=0; i<points.length; i++) {
        c2.lineTo(points[i][0], canvas.height-points[i][1]);
    }
    c2.lineTo(canvas.width, canvas.height);
    c2.closePath();
    c2.fill();
 }


 function doLandscape(){
    var colors;
    
    if (Math.random()>0.5) {
        colors = [
            "rgb(195, 157, 224)",
            "rgb(158, 98, 204)",
            "rgb(130, 79, 138)",
            "rgb(68, 28, 99)",
            "rgb(49, 7, 82)",
            "rgb(23, 3, 38)",
            "rbg(240, 203, 163)"
        ];
    } else {
        colors = [
            "#db3806", "#e0571d", "#e23a18", "#e83d12",  "#f46633", "#ff8000"
        ];
    }
    
    var height = 0;
    var width = 0;
        
    window.onresize = function(){
        var positionInfo = document.getElementsByTagName("body")[0].getBoundingClientRect();
        height = positionInfo.height;
        width = positionInfo.width;
        var canvas = document.getElementsByTagName('canvas')[0];
        canvas.width  = width;
        canvas.height = height;
        canvas.style.width  = width+'px';
        canvas.style.height = height+'px';
    };
    window.onresize();

    var layer_1 = midpoint_displacement([250, 0], [width, 200], 1.4, 20, 12)
    var layer_2 = midpoint_displacement([0, 180], [width, 80], 1.2, 30, 12)
    var layer_3 = midpoint_displacement([0, 270], [width, 190], 1, 120, 9)
    var layer_4 = midpoint_displacement([0, 350], [width, 320], 0.9, 250, 8)

    var layer_5 = midpoint_displacement([0, 50], [width, 50], 0.9, 15, 4)
    var layer_6 = midpoint_displacement([0, 20], [width, 20], 0.9, 10, 4)
    var layer_7 = midpoint_displacement([0, 10], [width, 20], 0.9, 20, 4)

    draw(layer_4, colors[0], true);
    draw(layer_3, colors[1]);
    draw(layer_2, colors[2]);
    draw(layer_1, colors[3]);
    
    draw(layer_5, colors[4]);
    draw(layer_6, colors[5]);
    draw(layer_7, colors[6]);
 }
 doLandscape();
	<html>
	<head>
	<style>
	body, html {
	margin: 0;
	padding: 0;
	height: 100vh;
	width: 100vw;
	overflow: none;
	}
	canvas {
	}
	</style>
	</head>
	<body>
	<canvas id="land"></canvas>
	</body>
	<script src="main.js" type="application/javascript"></script>
	</html>
	// Iterative midpoint vertical displacement
	function locationOf(element, array, comparer, start, end) {
	if (array.length === 0)
	return -1;

	start = start \|\| 0;
	end = end \|\| array.length;
	var pivot = (start + end) >> 1; // should be faster than the above calculation

	var c = comparer(element, array[pivot]);
	if (end - start <= 1) return c == -1 ? pivot - 1 : pivot;

	switch (c) {
	case -1: return locationOf(element, array, comparer, start, pivot);
	case 0: return pivot;
	case 1: return locationOf(element, array, comparer, pivot, end);
	};
	};

	// sample for objects like {lastName: 'Miller', ...}
	var cmpPoint = function (a, b) {
	if (a[0] < b[0]) return -1;
	if (a[0] > b[0]) return 1;
	return 0;
	}

	Array.prototype.insertOrdered = function (element, cmp) {
	var array = this.slice();
	array.splice(locationOf(element, array, cmp) + 1, 0, element);
	return array;
	};


	function midpoint_displacement(start, end, roughness, vertical_displacement, num_of_iterations){
	/*
	Given a straight line segment specified by a starting point and an endpoint
	in the form of [starting_point_x, starting_point_y] and [endpoint_x, endpoint_y],
	a roughness value > 0, an initial vertical displacement and a number of
	iterations > 0 applies the midpoint algorithm to the specified segment and
	returns the obtained list of points in the form
	points = [[x_0, y_0],[x_1, y_1],...,[x_n, y_n]]
	*/

	if (!num_of_iterations) { num_of_iterations = 16 }
	// Final number of points = (2^iterations)+1
	if (vertical_displacement == null) {
	// if no initial displacement is specified set displacement to:
	// (y_start+y_end)/2
	vertical_displacement = (start[1]+end[1])/2
	}
	// Data structure that stores the points is a list of lists where
	// each sublist represents a point and holds its x and y coordinates:
	// points=[[x_0, y_0],[x_1, y_1],...,[x_n, y_n]]
	// \| \| \|
	// point 0 point 1 point n
	// The points list is always kept sorted from smallest to biggest x-value
	var points = [start, end];
	var iteration = 1;
	while( iteration <= num_of_iterations ){
	// Since the list of points will be dynamically updated with the new computed
	// points after each midpoint displacement it is necessary to create a copy
	// of the state at the beginning of the iteration so we can iterate over
	// the original sequence.
	// Tuple type is used for security reasons since they are immutable in Python.

	var points_tup = points.slice();
	for (var i=0; i<points_tup.length-1; i++) {
	// Calculate x and y midpoint coordinates:
	var midpoint = [
	(points_tup[i][0]+points_tup[i+1][0])/2,
	(points_tup[i][1]+points_tup[i+1][1])/2
	];
	// Displace midpoint y-coordinate
	midpoint[1] += (Math.random()> 0.5)?-vertical_displacement:vertical_displacement;
	// Insert the displaced midpoint in the current list of points
	points = points.insertOrdered(midpoint, cmpPoint);
	}
	// Reduce displacement range
	vertical_displacement = 2 * (-roughness)
	// update number of iterations
	iteration += 1
	}

	return points
	}


	function draw(points, color, clear) {
	var canvas = document.getElementById('land');
	var c2 = canvas.getContext('2d');

	if (clear) {
	c2.clearRect(0, 0, canvas.width, canvas.height);
	}
	c2.fillStyle = color;

	c2.beginPath();
	c2.moveTo(0, canvas.height);
	for (var i=0; i<points.length; i++) {
	c2.lineTo(points[i][0], canvas.height-points[i][1]);
	}
	c2.lineTo(canvas.width, canvas.height);
	c2.closePath();
	c2.fill();
	}


	function doLandscape(){
	var colors;

	if (Math.random()>0.5) {
	colors = [
	"rgb(195, 157, 224)",
	"rgb(158, 98, 204)",
	"rgb(130, 79, 138)",
	"rgb(68, 28, 99)",
	"rgb(49, 7, 82)",
	"rgb(23, 3, 38)",
	"rbg(240, 203, 163)"
	];
	} else {
	colors = [
	"#db3806", "#e0571d", "#e23a18", "#e83d12", "#f46633", "#ff8000"
	];
	}

	var height = 0;
	var width = 0;

	window.onresize = function(){
	var positionInfo = document.getElementsByTagName("body")[0].getBoundingClientRect();
	height = positionInfo.height;
	width = positionInfo.width;
	var canvas = document.getElementsByTagName('canvas')[0];
	canvas.width = width;
	canvas.height = height;
	canvas.style.width = width+'px';
	canvas.style.height = height+'px';
	};
	window.onresize();

	var layer_1 = midpoint_displacement([250, 0], [width, 200], 1.4, 20, 12)
	var layer_2 = midpoint_displacement([0, 180], [width, 80], 1.2, 30, 12)
	var layer_3 = midpoint_displacement([0, 270], [width, 190], 1, 120, 9)
	var layer_4 = midpoint_displacement([0, 350], [width, 320], 0.9, 250, 8)

	var layer_5 = midpoint_displacement([0, 50], [width, 50], 0.9, 15, 4)
	var layer_6 = midpoint_displacement([0, 20], [width, 20], 0.9, 10, 4)
	var layer_7 = midpoint_displacement([0, 10], [width, 20], 0.9, 20, 4)

	draw(layer_4, colors[0], true);
	draw(layer_3, colors[1]);
	draw(layer_2, colors[2]);
	draw(layer_1, colors[3]);

	draw(layer_5, colors[4]);
	draw(layer_6, colors[5]);
	draw(layer_7, colors[6]);
	}
	doLandscape();