我是第一年从事机器人和机器人测试环境项目的计算机编程学生。 虽然我是Stackoverflow的新手，但我很清楚我们不应该帮忙完成作业或家庭作业。 我很难理解为什么会发生这种行为，所以了解它为什么会发生这样做真的很有帮助。
我们正在使用Processing库来用Java编程。 我们的任务是创建一个机器人测试环境，并创建三个执行不同运动的机器人。
我尝试编程的动作是Patrol，这意味着只需绕过屏幕边缘。 预期的行为是前进直到它到达墙壁，向左转（逆时针90度），然后再前进。 该项目与我们的Math课程相结合。话虽这么说，我们不能使用像rotate（），translate（），pushMatrix（）和popMatrix（）这样的方法来帮助旋转表格（每个机器人都是一个三角形）。
因此，旋转三角形的步骤是： 1）使用相同的平移将其中心点转换为原点（0,0）和顶点; 2）旋转所有点，其中（x，y）变为（y，-x）; 3）转换回正确的位置（步骤1翻译的倒数）。
我设置了一些边界if if语句将三角形放回屏幕，如果在旋转之后，任何内容都会脱离屏幕。
我的问题
转弯后，三角形出现在奇怪的位置，就像传送一样。
我添加了几行，这样我们就可以获得每个顶点的坐标，它的方向以及检测方向的变化。
代码
有两个文件：TestRobots，Robot。
机器人：
import processing.core.PApplet;
public class Robot{
int colour;
String name;
float width;
float height;
float x1;
float y1;
float x2;
float y2;
float x3;
float y3;
int direction;
int speed;
float centralPointX = width/2;
float centralPointY = height/2;
PApplet parent;
public Robot(PApplet parent, String name, int colour, float x1, float y1, float x2, float y2, float x3, float y3, int speed){
this.parent = parent;
this.name = name;
this.colour = colour;
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
this.x3 = x3;
this.y3 = y3;
this.speed = speed;
direction=4;
width = x2-x3;
if (width < 0){
width *= -1;
}
if (y2 > y3){
height = y2-y1;
}else{
height = y3-y1;
}
if (height < 0){
height *= -1;
}
if (y1<y2 && y1<y3){
direction=4;
}
}
public void drawRobot(){
parent.fill(colour);
parent.triangle(x1, y1, x2, y2, x3, y3);
parent.ellipseMode(parent.CENTER);
parent.ellipse(x1, y1, 3, 3);
}
public void moveForward(){
if(x1<parent.width || y1 <parent.height || x1 > 0 || y1 > 0){
switch (direction){
case 1:
x1 += speed;
x2 += speed;
x3 += speed;
break;
case 2:
y1 += speed;
y2 += speed;
y3 += speed;
break;
case 3:
x1 -= speed;
x2 -= speed;
x3 -= speed;
break;
case 4:
y1 -= speed;
y2 -= speed;
y3 -= speed;
break;
}
}
}
public void turnLeft(){
//Store original coordinates.
float tempX1 = x1;
float tempY1 = y1;
float tempX2 = x2;
float tempY2 = y2;
float tempX3 = x3;
float tempY3 = y3;
//Calculate translation of the central point of triangle to the origin.
float xTranslation = 0 - centralPointX;
float yTranslation = 0 - centralPointY;
//Translate all points by the translation calculated.
float translatedX1 = tempX1 + xTranslation;
float translatedY1 = tempY1 + yTranslation;
float translatedX2 = tempX2 + xTranslation;
float translatedY2 = tempY2 + yTranslation;
float translatedX3 = tempX3 + xTranslation;
float translatedY3 = tempY3 + yTranslation;
//Rotate all points 90 degrees counterclockwise, (x, y) --> (y, -x).
float rotatedX1 = translatedY1;
float rotatedY1 = -translatedX1;
float rotatedX2 = translatedY2;
float rotatedY2 = -translatedX2;
float rotatedX3 = translatedY3;
float rotatedY3 = -translatedX3;
//Translate all points back.
x1 = rotatedX1 - xTranslation;
y1 = rotatedY1 - yTranslation;
x2 = rotatedX2 - xTranslation;
y2 = rotatedY2 - yTranslation;
x3 = rotatedX3 - xTranslation;
y3 = rotatedY3 - yTranslation;
//Check which y and which x are the smallest, in order to correct any negative numbers.
float minX;
float minY;
if (y1<y2 && y1<y3){
minY = y1;
} else if (y2<y1 && y2<y3){
minY = y2;
} else {
minY = y3;
}
if (x1<x2 && x1<x3){
minX = x1;
} else if (x2<x1 && x2<x3){
minX = x2;
} else {
minX = x3;
}
//Check which y and which x are the biggest, in order to correct any out-of-screen draws.
float maxX;
float maxY;
if (y1>y2 && y1>y3){
maxY = y1;
} else if (y2>y1 && y2>y3){
maxY = y2;
} else {
maxY = y3;
}
if (x1>x2 && x1>x3){
maxX = x1;
} else if (x2>x1 && x2>x3){
maxX = x2;
} else {
maxX = x3;
}
//Correct position if any coordinate is negative.
if((minY-speed)<=minY){
float differenceY = -minY + 10;
y1 += differenceY;
y2 += differenceY;
y3 += differenceY;
}
if(x1<=(x1-speed)){
float differenceX = -minX + 10;
x1 += differenceX;
x2 += differenceX;
x3 += differenceX;
}
//Correct position if any coordinate is bigger than the screen size.
if((parent.height<=(maxY+speed))){
float differenceY = (-maxY+parent.height) + 10;
y1 -= differenceY;
y2 -= differenceY;
y3 -= differenceY;
}
if((x1+speed)>=parent.width){
float differenceX = (-maxX+parent.width) + 10;
x1 -= differenceX;
x2 -= differenceX;
x3 -= differenceX;
}
//Change direction variable and adjust it between 0 and 4.
direction -=1;
if (direction == 0){
direction = 4;
}
}
public void patrol(){
System.out.println("Direction is: "+ direction);
if(((y1-speed)<= 0)||((y1+speed)>= parent.height) || ((x1+speed)>=parent.width)||((x1-speed)<=0)){
turnLeft();
System.out.println("The NEW direction is: "+ direction);
}
moveForward();
}
}
TestRobots：
import processing.core.PApplet;
public class TestRobots extends PApplet{
Robot alice = new Robot(this, "Alice", 255, 257f, 389f, 309f, 450f, 209f, 450f, 3);
public static void main(String[] args){
PApplet.main("TestRobots");
}
public void settings(){
size(1000, 500);
}
public void setup(){
frameRate(30);
}
public void draw(){
background(255);
alice.patrol();
System.out.println("x1 = "+ alice.x1);
System.out.println("y1 = "+ alice.y1);
System.out.println("x2 = "+ alice.x2);
System.out.println("y2 = "+ alice.y2);
System.out.println("x3 = "+ alice.x3);
System.out.println("y3 = "+ alice.y3);
alice.drawRobot();
}
}
这是生成的输出的打印。我剪断了改变方向的部分：
Direction is: 2
x1 = 62.0
y1 = 497.0
x2 = 10.0
y2 = 436.0
x3 = 110.0
y3 = 436.0
The NEW direction is: 1
x1 = 500.0
y1 = 58.0
x2 = 439.0
y2 = 110.0
x3 = 439.0
y3 = 10.0
这里有同样奇怪的行为：
Direction is: 4
x1 = 257.0
y1 = 2.0
x2 = 309.0
y2 = 63.0
x3 = 209.0
y3 = 63.0
The NEW direction is: 3
x1 = -1.0
y1 = 62.0
x2 = 60.0
y2 = 10.0
x3 = 60.0
y3 = 110.0
The NEW direction is: 2
x1 = 62.0
y1 = 74.0
x2 = 10.0
y2 = 13.0
x3 = 110.0
y3 = 13.0
非常感谢您在此之前阅读，如果我不够清楚，请提前抱歉。这是我的第一个问题！
古斯塔沃
答案 0 :(得分：1)
我认为您的问题与变量centralPointX和centralPointY有关。看看你写的这段代码：
//Calculate translation of the central point of triangle to the origin.
float xTranslation = 0 - centralPointX;
float yTranslation = 0 - centralPointY;
//Translate all points by the translation calculated.
float translatedX1 = tempX1 + xTranslation;
float translatedY1 = tempY1 + yTranslation;
float translatedX2 = tempX2 + xTranslation;
float translatedY2 = tempY2 + yTranslation;
float translatedX3 = tempX3 + xTranslation;
float translatedY3 = tempY3 + yTranslation;
从这一点看，您认为centralPointX和centralPointY表示三角形的中心......但是，请看它们的定义位置：
float centralPointX = width/2;
float centralPointY = height/2;
所以他们实际上并不代表中心xy坐标。你需要做的是修复这个部分：
//Calculate translation of the central point of triangle to the origin.
float xTranslation = 0 - centralPointX;
float yTranslation = 0 - centralPointY;
这样它实际上就是评论所说的应该做的，即计算三角形中心的x和y坐标。
我不会为你实现这个，因为正如你所说，这是功课。但是，我认为这绝对应该指向正确的方向。另外，保持良好的工作。我希望每个第一个问题都经过深思熟虑。