[从头学数学] 第66节 观察物体（二）

剧情提要：
[机器小伟]在[工程师阿伟]的陪同下进入练气期第八层功法的修炼，
这次要修炼的目标是[观察物体（二）]。

正剧开始：

星历2016年02月01日 13:20:45, 银河系厄尔斯星球中华帝国江南行省。
[工程师阿伟]正在和[机器小伟]一起观察着物体。

今天主要观察的是立方体，是要看它们的三视图：

既然立方体是属于三维的图形，那么再继续用二维的坐标系就不是那么合适了，于是阿伟就借着这个机会，新增了三维坐标系：

又新增了立方体的绘制和三视图的显示功能：

小伟画三视图可是画得非常的尽兴。

果然人生最大的乐趣还是在于画画。

接下来小伟充分开动起了脑筋：

然后又做了一个计数的题：

这下所有的功法内容可都学会了，小伟很开心。

下面，小伟就把他所做的展示出来，这些图真的是看了很心旷神怡啊。

<span style="font-size:18px;">function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis2D(0, 0, 180);  
	
	var r = 50;
	var dx = r*1.5, dy = r*1.5;
	for (var i = 0; i < 3; i++) {
		for (var j = 0; j < 3; j++) {
			drawCubic(i * dx, j * dy, r, 'yellow');
		}
	}


}

	
/**
* @usage   绘制正方体
* @author  mw
* @date    2016年02月01日  星期一  08:40:27 
* @param
* @return
*
*/
function drawCubic(x0, y0, r, style) {
	plot.save()
		.translate(x0 + r/2, y0 - r/2);
	style = style ? style : 'black';
	//左下角[x0, y0，边长r
	shape.fillDraw(shape.nEdge(0, 0,0.707*r, 4, 0), style);
	shape.fillDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), 'white');
	shape.fillDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), 'white');
	plot.restore();

}

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis2D(0, 0, 180);  
	
	var r = 50;
	var dx = r, dy = r;
	for (var i = 0; i < 3; i++) {
		for (var j = 2; j > 0; j--) {
			drawCubic(i * dx, (j-2) * dy, r, 'red');
		}
	}


}

/**
* @usage   绘制三维直角坐标系
* @author  mw
* @date    2016年02月01日  星期一  09:52:05 
* @param
* @return
*
*/

	this.axis3D = function(x, y, z, r, style) {
		plot.save();
		
		style = style ? style : 'black';
		y = -y;
		x = x-0.707*z;
		y = y+0.707*z;
		z = 0;
		
		var zxOffset = z*0.707+x;
		var zyOffset = z*0.707+y;
		var zr = r*0.707;

		
		plot.setFillStyle(style)
			.setStrokeStyle(style);
			
		plot.beginPath()
			.moveTo(x-r,y)
			.lineTo(x+r,y)
			.closePath()
			.stroke();
			
		plot.beginPath()
			.moveTo(x,y-r)
			.lineTo(x,y+r)
			.closePath()
			.stroke();	

		plot.beginPath()
			.moveTo(zxOffset+zr*0.5,zyOffset-zr*0.5)
			.lineTo(zxOffset-zr, zyOffset + zr)
			.closePath()
			.stroke();	

		
		var r0 = 10;
		
		//x轴箭头
		plot.beginPath()
			.moveTo(x+r- r0*Math.cos(Math.PI/3), y-r0*Math.sin(Math.PI/3))
			.lineTo(x+r+r0*Math.sin(Math.PI/3), y)
			.lineTo(x+r -r0*Math.cos(Math.PI/3), y+r0*Math.sin(Math.PI/3))
			.closePath()
			.fill()
		
		plot.fillText("X", x+r, y-10, 20);
		plot.fillText("Y", x+10, y-r+10, 20);
		plot.fillText("Z", zxOffset-zr-25, zyOffset+zr+25, 20);
		
		//y轴箭头
		plot.beginPath()
			.moveTo(x+ r0*Math.sin(Math.PI/3), y-r+r0*Math.cos(Math.PI/3))
			.lineTo(x, y-r-r0*Math.sin(Math.PI/3))
			.lineTo(x-r0*Math.sin(Math.PI/3), y-r+r0*Math.cos(Math.PI/3))
			.closePath()
			.fill()
		
		//z轴箭头
		plot.beginPath()
			.moveTo(zxOffset -zr - r0*0.866*0.707, 
					zyOffset+zr-r0*0.866*0.707)
			.lineTo(zxOffset-zr+r0*0.866*0.707, zyOffset+zr+r0*0.866*0.707)
			.lineTo(zxOffset-zr -r0*1.5*0.707, zyOffset+zr+r0*1.5*0.707)
			.closePath()
			.fill()
		
		plot.restore();
	}	

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  
	config.axis3D(0, 0, 20, 180, 'red'); 
	config.axis3D(-50, -80, 0, 180, 'blue'); 
	
	/*
	var r = 50;
	var dx = r, dy = r;
	for (var i = 0; i < 3; i++) {
		for (var j = 2; j > 0; j--) {
			drawCubic(i * dx, (j-2) * dy, r, 'red');
		}
	}
*/

}


/**
* @usage   绘制正方体
* @author  mw
* @date    2016年02月01日  星期一  08:40:27 
* @param
* @return
*
*/
this.drawCubic = function(x0, y0, z0, r, style) {
	plot.save();
	z0 = z0 /2;
	x0 = x0 - z0*0.707;
	y0 = y0 + z0*0.707;
	z0 = 0;
	
	plot.translate(x0 + r/2, y0 - r/2);
	
	style = style ? style : 'black';
	//左下角[x0, y0，边长r
	shape.fillDraw(shape.nEdge(0, 0,0.707*r, 4, 0), style);
	shape.fillDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), 'white');
	shape.fillDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), 'white');
	plot.restore();

}

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//x, y, z坐标序列
	var x1, y1, z1;
	//立方体序列
	var cubic = new Array();
	
	
	x1 = [0];
	y1 = 0;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	
	x1 = [0, 1, 2];
	y1 = 0;
	z1 = 1;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	

	
	var r = 50;
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, cubic[i][1]*r, cubic[i][2]*r, r, '#884422');
	}

}

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//x, y, z坐标序列
	var x1, y1, z1;
	//立方体序列
	var cubic = new Array();
	
	
	x1 = [0];
	y1 = 0;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	
	x1 = [0, 1, 2];
	y1 = 0;
	z1 = 1;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	

	
	var r = 50;
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, cubic[i][1]*r, cubic[i][2]*r, r, '#884422');
	}
	
	var height = 400;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/4, 100);
	plot.fillText('俯视图', 20, 20+2*height/4, 100);
	
	plot.setFillStyle('#884422')
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(4,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(4,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(4,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}

}

/**
* @usage   绘制正方体
* @author  mw
* @date    2016年02月01日  星期一  08:40:27 
* @param
* @return
*
*/
this.drawCubic = function(x0, y0, z0, r, style) {
	plot.save();
	y0 = -y0;
	z0 = z0 /2;
	x0 = x0 - z0*0.707;
	y0 = y0 - z0*0.707;
	z0 = 0;
	
	plot.translate(x0 + r/2, y0 - r/2);
	
	style = style ? style : 'black';
	//左下角[x0, y0，边长r
	shape.fillDraw(shape.nEdge(0, 0,0.707*r, 4, 0), style);
	shape.fillDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(-0.5*r, 0.5*r, 0, r, r/2, Math.PI/4), 'white');
	shape.fillDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), style);
	shape.strokeDraw(shape.paraquad(0.5*r, -0.5*r, Math.PI/4, r/2, r, Math.PI/4), 'white');
	plot.restore();

}
	
function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//x, y, z坐标序列
	var x1, y1, z1;
	//立方体序列
	var cubic = new Array();
	
	
	x1 = [0,1,2];
	y1 = 0;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	
	x1 = [0];
	y1 = 1;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	

	
	var r = 50;
	var style = 'blue';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/2;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/4, 100);
	plot.fillText('俯视图', 20, 20+2*height/4, 100);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(4,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(4,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(4,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}

}

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//x, y, z坐标序列
	var x1, y1, z1;
	//立方体序列
	var cubic = new Array();
	
	
	x1 = 0;
	y1 = 0;
	z1 = 0;
	
	for (var i = 0; i <1; i++) {
		cubic.push([x1, y1, z1]);
	}
	
	x1 = 0;
	y1 = [0,1,2];
	z1 = 1;
	
	for (var i = 0; i < y1.length; i++) {
		cubic.push([x1, y1[i], z1]);
	}
	
	
	x1 = 0;
	y1 = 0;
	z1 = 2;
	
	for (var i = 0; i < 1; i++) {
		cubic.push([x1, y1, z1]);
	}

	
	var r = 50;
	var style = '#ccaa00';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, -cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/2;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/3, 100);
	plot.fillText('俯视图', 20, 20+2*height/3, 100);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(3,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(3,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(3,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}

}

function myDraw() {  
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//x, y, z坐标序列
	var x1, y1, z1;
	//立方体序列
	var cubic = new Array();
	
	
	x1 = [0,1,2];
	y1 = 0;
	z1 = 0;
	
	for (var i = 0; i <x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	
	x1 = [2];
	y1 = 1;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}
	
	
	x1 = [2];
	y1 = 2;
	z1 = 0;
	
	for (var i = 0; i < x1.length; i++) {
		cubic.push([x1[i], y1, z1]);
	}

	
	var r = 50;
	var style = '#ccaa00';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, -cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/2;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/3, 100);
	plot.fillText('俯视图', 20, 20+2*height/3, 100);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(3,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(3,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(3,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}

}

//6 请把它摆出来
function myDraw() { 

	
	
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//立方体，按从左向右(x递增)，从下向上(y递增)，从后向前(z递增)的顺序压入
	var cubic = new Array();
	//从前面看缺少的[x,y]
	var notfront = [[0,1],[1,1],[3,1]];
	//从上面看缺少的[x, z]
	var nottop = [[0,1],[1,1]];
	//从左面看缺少的[z,y]
	var notleft = [[1,1]];
	
	
	for (var z = 0; z < 2; z++) {
		for (var y = 0; y < 2; y++) {
			for (var x = 0; x < 4; x++) {
			
				/*
				if (elementInArray([x, y], notfront) ||
					elementInArray([x, z], nottop) ||
					elementInArray([z, y], notleft)) {
					continue;
				}*/
				cubic.push([x,y,z]);
			}
		}
	}
	
	
	//三维图和三视图
	var r = 50;
	var style = '#ccaa00';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/2;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/3, 100);
	plot.fillText('俯视图', 20, 20+2*height/3, 100);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(3,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(3,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(3,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}
		
}
	
function elementInArray(x, array) {
	var elem = new Array(x);
	var elemLen = elem.length;
	var a = new Array(array);
	var len = a.length;
	
	if (elemLen > 1) {
		for (var i = 0; i < len; i++) {
			for (var j = 0; j < elemLen; j++) {
				if (a[i][j] != x[j]) {
					break;
				}
				if (j >= elemLen-1) {
					return true;
				}
			}
			
		}
	} else {
		for (var i = 0; i < len; i++) {
			if (a[i] == x) {
				return true;
			}
		}
	}
	
	return false;
}

//6 请把它摆出来
function draw() { 
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//立方体，按从左向右(x递增)，从下向上(y递增)，从后向前(z递增)的顺序压入
	var cubic = new Array();
	//从前面看缺少的[x,y]
	var notfront = [[0,1],[1,1],[3,1]];
	//从上面看缺少的[x, z]
	var nottop = [[0,0],[1,0]];
	//从左面看缺少的[z,y]
	var notleft = [[1,1]];
	
	
	for (var z = 0; z < 2; z++) {
		for (var y = 0; y < 2; y++) {
			for (var x = 0; x < 4; x++) {
			
				
				if (elementInArray([x, y], notfront) ||
					elementInArray([x, z], nottop) ||
					elementInArray([z, y], notleft)) {
					continue;
				}
				cubic.push([x,y,z]);
			}
		}
	}
	
	
	//三维图和三视图
	var r = 50;
	var style = '#ccaa00';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, -cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/2;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/3, 100);
	plot.fillText('俯视图', 20, 20+2*height/3, 100);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(3,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(3,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(3,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}
		
}
	
function elementInArray(x, array) {
	var elem = new Array(x);
	var elemLen = elem[0].length;
	var a = new Array();
	a = array;
	var len = a.length;
	
	if (elemLen > 1) {
		for (var i = 0; i < len; i++) {
			var test = 1;
			for (var j = 0; j < elemLen; j++) {
				
				if (a[i][j] != elem[0][j]) {
					test = 0;
				}
				
				if (test == 1 && j >= elemLen-1) {
					return 1;
				}
			}
			
		}
	} else {
		for (var i = 0; i < len; i++) {
			if (a[i] == x) {
				return 1;
			}
		}
	}
	
	return 0;
}

//7 有多少个立方体？
function draw() { 
    var config = new PlotConfiguration();  
    config.init();  
    config.setPreference(); 
	
	config.setSector(1,1,1,1);
 
    config.axis3D(0, 0, 0, 180);  

	//立方体，按从左向右(x递增)，从下向上(y递增)，从后向前(z递增)的顺序压入
	var cubic = new Array();

	
	for (var z = 0; z < 4; z++) {
		for (var y = 3; y > -1; y--) {
			for (var x = 0; x < 4; x++) {
			
				
				if (x + z <= y)
					cubic.push([x,4-y,z]);
			}
		}
	}
	
	
	//三维图和三视图
	var r = 40;
	var style = 'blue';
	
	for (var i = 0; i < cubic.length; i++) {
		shape.drawCubic(cubic[i][0]*r, 100-cubic[i][1]*r, cubic[i][2]*r, r, style);
	}
	
	var height = 400;
	r = r/3;
	
	plot.setTransform(1, 0, 0, 1, 0, 0);
	plot.fillText('左视图', 20, 20, 100);
	plot.fillText('主视图', 20, 20+1*height/3, 100);
	plot.fillText('俯视图', 20, 20+2*height/3, 100);
	plot.fillText('共有'+cubic.length.toFixed(0)+'个立方体组成。', 300,350,200);
	
	plot.setFillStyle(style)
		.setStrokeStyle('white');
		

	//左视图
	config.setSector(3,3,1,1);
	for (var i = 0; i < cubic.length; i++) {
		//y, z两坐标，z坐标变为x坐标
		shape.fillRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][2]*r, -cubic[i][1]*r, r, r);
	}
	
	//主视图
	config.setSector(3,3,2,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, y两坐标
		shape.fillRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, -cubic[i][1]*r, r, r);
	}
	
	//俯视图
	config.setSector(3,3,3,1);
	for (var i = 0; i < cubic.length; i++) {
		//x, z两坐标，z坐标变为y坐标
		shape.fillRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
		shape.strokeRect(cubic[i][0]*r, cubic[i][2]*r, r, r);
	}
		
}

</span>

本节到此结束，欲知后事如何，请看下回分解。