(九)利用processing展示简单函数的使用

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随机绘制直线:

void setup(){  size(480, 120);  smooth();  frameRate(2);}void draw(){  background(204);  for(int x = 20; x < width; x+=20){    float mx = mouseX/10;    float offsetA = random(-mx, mx);    float offsetB = random(-mx, mx);    line(x+offsetA, 20, x-offsetB, 100);  }  saveFrame("Shape.png");}

程序运行结果:

随机移动图像:

float speedX = 10.0;float speedY = 2.5;int diameter = 20;float x;float y;void setup(){  size(640, 120);  smooth();  x = width/2;  y = height/2;  randomSeed(20);}void draw(){  x += random(-speedX, speedX);  y += random(-speedY, speedY);  x = constrain(x, 0, width);  y = constrain(y, 0, height);  ellipse(x, y, diameter, diameter);}

程序运行结果:

函数使用说明:

randomSeed(Auto)    //设置种子数， Auto 相同的话生成的种子数相同，随机数也就是相同的random(-x, x)    //在-x 到 x 之间随机成生一个数字constrain(x, 0, width)    //将x 的值设置在(0, width)这范围中

时光流逝,计时器 timer:

//通过计时器实现一个圆形的向左向右移动int timer1 = 2000;int timer2 = 4000;float x;void setup(){  size(640, 120);  smooth();  x = width/2;}void draw(){  int currentTime = millis();  background(204);  if(currentTime > timer2){    x -= 0.5;  }else if(currentTime > timer1){    x += 0.5;  }  ellipse(x, 60, 90, 90);}

程序运行结果:

函数使用说明:

millis()    //返回当前程序的运行时间，单位为毫秒

实现sin函数的图形化显示:

float angle = 0.0;float x;float y;float stepX = 0.2;int rate = 0;void display_XY(){  line(40, 40, 40, 320);  line(40, height/2, width-100, height/2);  text("Y", 35, 35);  line(40, 40, 35, 45);  line(40, 40, 45, 45);  text("O", 30, height/2);  text("X", 560, height/2);  line(width-105, height/2-5,width-100, height/2);  line(width-105, height/2+5, width-100, height/2);  x = 40;  y = height/2;    strokeWeight(4);  point(x, y);  strokeWeight(1);}void setup(){  size(640, 360);  smooth();  background(204);  frameRate(120);  display_XY();}void draw(){  rate++;  if(rate == 60){    rate = 0;    }  angle += 0.5;  y = sin(radians(angle))*100+height/2;  x += stepX;  point(x, y);    if(y>-0.01+height/2 && y < 0.01 + height/2){      noStroke();      fill(255, 255, 0);      ellipse(x, y, 10, 10);      noFill();      stroke(0);    }  if(x >= 540){    saveFrame("Shape.png");    noLoop();    //exit();  }}

程序运行结果:

函数说明:

sin(float)   //读入弧度值，函数结果 位于 -1，1之间

利用sin()值做x, cos()值做y, 绘制小螺旋:

float angle = 0.0;float offset = 60;float scalar = 2;float speed = 0.05;void setup(){  size(120, 120);  fill(0);  smooth();}void draw(){  float x = offset + cos(angle) * scalar;  float y = offset + sin(angle) * scalar;  ellipse(x, y, 2, 2);  angle += speed;  scalar += speed;}

程序运行结果:

图形的平移，旋转和缩放:

float angle = 0.0;float angleDirection = 1;float speed = 0.005;void setup(){  size(200, 200);  smooth();}void draw(){  background(204);  translate(100, 100);  rotate(angle);  strokeWeight(12);  line(0, 0, 40, 0);  translate(40, 0);  rotate(angle * 2.0);  strokeWeight(6);  line(0, 0, 30, 0);  translate(30, 0);  rotate(angle * 3.0);  strokeWeight(3);  line(0, 0, 20, 0);    angle += speed*angleDirection;  if((angle > QUARTER_PI) || (angle < 0)){    angleDirection *= -1;  }  saveFrame("Shape.png");}

程序运行结果:

函数使用说明:

translate(x, y)    //设置x, y为新的 0，0点rotate(angle)     //将坐标系统进行旋转，angle为旋转的角度，旋转是绕着原点进行的scale(num)       //num 为缩放比例，同时笔画的粗细也会进行缩放,strokeWeight(1.0/num)修改笔画的权重nf(i, 4)               //nf(1, 4)指(0001), nf(11, 4)指(0011)

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