参考《代码本色》所进行的编程习作

目录
- 序章随机游走
- 第一章向量
- 第二章力
- 第三章震荡
- 第四章粒子系统

实验结果

应用的技术
①概率和非均匀分布绘制了一个小球使他有50%的概率向着鼠标所在的方向移动。
②perlin噪声如果小球没有向着鼠标运动（另外的50%概率），那么他就使用噪声noise()产生随机数值使小球随机移动一步。

实验代码

Walker w;
float tx=0;
float ty=10000;void setup() {size(640,360);w = new Walker();background(255);
}void draw() {w.step();w.display();
}class Walker {float x;float y;Walker() {x = width / 2;y = height / 2;}void display() {stroke(100,200,200);ellipse(x,y,16,16);}void step() {float r = random(1);if(r<0.5){                        //使得小球向鼠标运动的概率是0.5//小球向着鼠标方向移动if((x<mouseX) && (y<mouseY)){ x++;y++;}else if((x<mouseX) && (y>mouseY)){x++;y--;}else if((x>mouseX) && (y>mouseY)){x--;y--;}else if((x>mouseX) && (y<mouseY)){x--;y++;}}else if(r>0.5){x = x + noise(tx);//perlin噪声y = y + noise(ty);tx+=0.01;ty+=0.01;}}
}

第一章向量

实验结果

应用的技术
做了一个类似弹球的程序，当小球碰到鼠标小球就会被弹起，如果把鼠标移走，小球就会自然下落，当碰到窗口的边缘时也会被弹起。

①向量的加法小球即时的位置=（原来的位置.x+速度，原来的位置.y+速度)

②向量运动的速度和加速度小球运动时设置了大小方向恒定的加速度使得小球下落运动的速度越来越快。

实验代码

Mover mover;void setup() {size(300,300);mover = new Mover();
}void draw() {background(255);mover.update();mover.checkEdges();mover.display();
}class PVector {float x;float y;PVector(float x_,float y_) {x = x_;y = y_;}void add(PVector v) {x = x + v.x; y = y + v.y;}void sub(PVector v) {x = x - v.x;y = y - v.y;}void mult(float n) {x = x * n;y = y * n;}void div(float n) {x = x / n;y = y / n;}float mag() {return sqrt(x * x + y * y); }void normalize() {float m = mag();if(m != 0) {div(m);  }}void limit(float max) {if(mag() > max) {normalize();mult(max);}}
}class Mover {PVector location;PVector velocity;PVector acceleration;float topspeed;Mover() {location = new PVector(width/2,0);velocity = new PVector(random(-2,2),random(-2,2));//初始速度随机acceleration = new PVector(-0.001,0.1);//加速度大小方向恒定topspeed = 10;}void update() {    velocity.add(acceleration);//更新速度velocity.limit(topspeed);location.add(velocity); //更新位置}void display() {stroke(100,200,200);fill(100,200,200);ellipse(location.x,location.y,20,20);}void checkEdges() {//小球碰到鼠标后反弹if((location.x > mouseX) || (location.x < 0)) {velocity.x = velocity.x * -1; }if((location.y > mouseY) || (location.y < 0)) {velocity.y = velocity.y * -1; }}
}

第二章力

实验结果

应用的技术
①给小球施加外力(风力) 如果点击鼠标就可以给小球施加一个随机大小方向向右的风力。
②空气和流体阻力模拟了不同质量的物体在空气中和在流体中收到不同阻力的情况。

实验代码

Mover[] movers = new Mover[11];
Liquid liquid;
float flag=0;void mousePressed() {flag=random(0,0.5);//如果点击鼠标就随机给flag赋值
}void setup() {size(800,500);reset();liquid = new Liquid(0,height / 2,width, height / 2,0.1);
}void draw() {background(255);liquid.display();for(int i = 0; i < movers.length; i++) {if(liquid.contains(movers[i])) {PVector dragForce = liquid.drag(movers[i]);movers[i].applyForce(dragForce);//判断如果小球进入下面灰色的区域就施加流体阻力}PVector gravity = new PVector(0,0.1 * movers[i].mass);PVector wind = new PVector(flag,0);movers[i].applyForce(gravity);movers[i].applyForce(wind);movers[i].update();movers[i].display();movers[i].checkEdges();}}void reset() {for(int i = 0; i < movers.length; i++) {movers[i] = new Mover(random(0.5,3),40 + i * 70,0); }
}class PVector {float x;float y;PVector(float x_,float y_) {x = x_;y = y_;}PVector get() {PVector newVector = new PVector(x,y);return newVector;}void add(PVector v) {x = x + v.x; y = y + v.y;}void sub(PVector v) {x = x - v.x;y = y - v.y;}void mult(float n) {x = x * n;y = y * n;}void div(float n) {x = x / n;y = y / n;}float mag() {return sqrt(x * x + y * y); }void normalize() {float m = mag();if(m != 0) {div(m);  }}void limit(float max) {if(mag() > max) {normalize();mult(max);println(mag());}}
}class Mover {PVector location;PVector velocity;PVector acceleration;float mass;color c;Mover(float m,float x,float y) {location = new PVector(x,y);velocity = new PVector(0,0);acceleration = new PVector(0,0);mass = m;c = color(random(255),random(255),random(255));}void applyForce(PVector force) {PVector newVector = force.get();newVector.div(mass);acceleration.add(newVector);}void update() {velocity.add(acceleration);location.add(velocity);acceleration.mult(0);}void display() {stroke(0);strokeWeight(2);fill(c);ellipse(location.x,location.y,mass * 16,mass * 16);}void checkEdges() {if(location.y > height) {velocity.y *= -0.9;  location.y = height;}if(location.x > width) {velocity.x *= -0.5;  location.x = width;}}
}class Liquid {float x,y,w,h;float c;Liquid(float x_,float y_,float w_,float h_,float c_) {x = x_;y = y_;w = w_;h = h_;c = c_;}// is the mover in the liquid?boolean contains(Mover m) {PVector l = m.location;if(l.x > x && l.x < x + w && l.y > y && l.y < y + h) {return true; } else {return false;}}PVector drag(Mover m) {float speed = m.velocity.mag();float dragMagnitude = c * speed * speed;PVector dragForce = m.velocity.get();dragForce.mult(-1);dragForce.normalize();dragForce.mult(dragMagnitude);return dragForce;}void display() {noStroke();fill(50);rect(x,y,w,h);}
}

第三章震荡

实验结果

应用的技术
①指向运动的方向屏幕中有一个长方形小物体会跟随鼠标移动，它运动的方向始终指向鼠标的方向。
②弹力屏幕上有一个模拟的弹球装置，当长方形小物体靠近它时会给他施加一个外力使得弹力小球朝小物体相反的方向弹走。

实验代码

Bob bob;
Spring spring;
float flag=0;
float one=0;
Mover mover;void setup() {size(800,500);spring = new Spring(width/2,10,100); bob = new Bob(width/2,100); mover = new Mover();
}void draw()  {background(255); mover.update();mover.display();PVector gravity = new PVector(0,2);PVector zhuang = new PVector(one,0);//在x方向上撞击的力和在y方向上的拉力if(mover.location.x>400){one=random(-10,0);   }else{one=random(0,10);}if(mover.location.y>bob.location.y){flag=random(-1,0);}else{flag=random(0,10);}bob.applyForce(zhuang);bob.applyForce(gravity);spring.connect(bob);spring.display(); spring.displayLine(bob);bob.update();bob.display(); }class Spring {PVector anchor;float len;float k = 0.1;Spring(float x,float y,int l) {anchor = new PVector(x,y);len = l;}void connect(Bob b) {PVector force = b.location.get();force.sub(anchor);float d = force.mag();float stretch = d - len;force.normalize();force.mult(-1 * k * stretch);b.applyForce(force);}void display() { stroke(0);fill(175);strokeWeight(2);rectMode(CENTER);rect(anchor.x, 150, 10, 10);}void displayLine(Bob b) {strokeWeight(2);stroke(0);line(b.location.x, b.location.y, anchor.x, 150);}
}class Bob { PVector location;PVector velocity;PVector acceleration;float mass = 24;float damping = 0.98;Bob(float x, float y) {location = new PVector(x,y);velocity = new PVector(0,0);acceleration = new PVector(0,0);} void update() { velocity.add(acceleration);velocity.mult(damping);location.add(velocity);acceleration.mult(0);}void applyForce(PVector force) {PVector f = force.get();f.div(mass);acceleration.add(f);}void display() { stroke(0);strokeWeight(2);fill(175);ellipse(location.x,location.y,mass * 2,mass * 2);}
}class Mover {PVector location;PVector velocity;PVector acceleration;float topspeed;float xoff,yoff;float r = 16;Mover() {location = new PVector(width / 2,height / 2);velocity = new PVector(0,0);topspeed = 4;xoff = 1000;yoff = 0;}void update() {PVector mouse = new PVector(mouseX,mouseY);PVector dir = mouse.get();dir.sub(location);dir.normalize();dir.mult(0.5);acceleration = dir;velocity.add(acceleration);velocity.limit(topspeed);location.add(velocity);}void display() {float theta = velocity.heading2D();stroke(0);strokeWeight(2);fill(127);pushMatrix();rectMode(CENTER);translate(location.x,location.y);rotate(theta);rect(0,0,30,10);popMatrix();}
}class PVector {float x;float y;PVector(float x_,float y_) {x = x_;y = y_;}PVector get() {PVector newVector = new PVector(x,y);return newVector;}void add(PVector v) {x = x + v.x; y = y + v.y;}void sub(PVector v) {x = x - v.x;y = y - v.y;}void mult(float n) {x = x * n;y = y * n;}void div(float n) {x = x / n;y = y / n;}float mag() {return sqrt(x * x + y * y); }void normalize() {float m = mag();if(m != 0) {div(m);  }}void limit(float max) {if(mag() > max) {normalize();mult(max);}}float heading2D() {return atan2(y,x); }
}

第四章粒子系统

实验结果

应用的技术
①由粒子系统组成的系统会在鼠标单击的地方产生一个粒子系统，整个程序会有很多个粒子系统，由他们再组成了一个系统，对这个系统进行的一些操作。

②受力作用的粒子系统给产生的这些粒子施加一个重力（图中是因为我把重力的数值设置的有点小，如果调大重力的话就可以看见这些像素小点直直下落无法飞起来形成喷射效果）。

实验代码

import java.util.Iterator;ArrayList<ParticleSystem> systems;void setup() {size(800,500);systems = new ArrayList<ParticleSystem>();
}void draw() {background(255);PVector g = new PVector(0,0.1);for(ParticleSystem ps : systems) {  //遍历每一个粒子系统ps.applyForce(g);                //给粒子系统施加重力就是给上面的每一个粒子施加重力ps.run();ps.addParticle();}
}void mousePressed() {//在鼠标点击处制造新的粒子系统systems.add(new ParticleSystem(1,new PVector(mouseX,mouseY)));
}class ParticleSystem {ArrayList<Particle> particles;PVector origin;ParticleSystem(int num,PVector v) {particles = new ArrayList<Particle>();origin = v.get();for(int i = 0; i < num; i++) {particles.add(new Particle(origin)); }}void addParticle() {particles.add(new Particle(origin)); }void addParticle(Particle p) {particles.add(p); }void applyForce(PVector f){for(Particle p : particles){p.applyForce(f);}}void run() {Iterator<Particle> it = particles.iterator();  while(it.hasNext()) {Particle p = it.next();p.run();if(p.isDead()) {it.remove(); }}    }boolean dead() {if(particles.isEmpty()) {return true; } else {return false; }}
}class Particle {PVector location;PVector velocity;PVector acceleration;float lifespan;float mass=1;color c;Particle(PVector l) {acceleration = new PVector(0,0);velocity = new PVector(random(-1,1),random(-2,0));location = l.get();        lifespan = 255;c = color(random(255),random(255),random(255));}void run() {update();display();}void applyForce(PVector force) {PVector f=force.get();f.div(mass);acceleration.add(f);}void update() {velocity.add(acceleration);location.add(velocity);acceleration.mult(0);lifespan -= 2.0;}void display() {stroke(c,lifespan);strokeWeight(5);fill(c,lifespan);point(location.x,location.y);}boolean isDead() {if(lifespan < 0.0) {return true; } else {return false; }}
}class PVector {float x;float y;PVector() {x = 0;y = 0;}PVector(float x_,float y_) {x = x_;y = y_;}PVector get() {PVector newVector = new PVector(x,y);return newVector;}void add(PVector v) {x = x + v.x; y = y + v.y;}void sub(PVector v) {x = x - v.x;y = y - v.y;}void mult(float n) {x = x * n;y = y * n;}void div(float n) {x = x / n;y = y / n;}float mag() {return sqrt(x * x + y * y); }void normalize() {float m = mag();if(m != 0) {div(m);  }}void limit(float max) {if(mag() > max) {normalize();mult(max);}}float heading2D() {return atan2(y,x); }}