wk17

我們今天要做出這個

void setup(){

  size(300,300);

}

void draw(){

  background(#002966);

  stroke(#b7efff);///筆，外框

  line(100,150,200,150);

  

  fill(#b7efff);///填充顏色

  ellipse(100,150,13,13);

  ellipse(200,150,13,13);

}

滑鼠放開時會變回原來的長度

全長 len

只動 (len-100)

比例: (len-100)/len

void setup(){

  size(300,300);

}

float x=100,y=100;

void draw(){

  background(#002966);

  stroke(#b7efff);

  line(x,y,200,150);

  

  fill(#b7efff);

  ellipse(x,y,13,13);

  ellipse(200,150,13,13);

  if(! mousePressed ){

    float dx=x-200;

    float dy=y-150;

    float len=sqrt(dx*dx+dy*dy);

    x-=dx*(len-100)/len;

    y-=dy*(len-100)/len;

  }

}

void mouseDragged(){

  x=mouseX;

  y=mouseY;

}

讓他一次跑1/10

void setup(){

  size(300,300);

}

float x=100,y=100;

void draw(){

  background(#002966);

  stroke(#b7efff);

  line(x,y,200,150);

  

  fill(#b7efff);

  ellipse(x,y,13,13);

  ellipse(200,150,13,13);

  if(! mousePressed ){

    float dx=x-200;

    float dy=y-150;

    float len=sqrt(dx*dx+dy*dy);

    x-=dx*(len-100)/len*0.1;

    y-=dy*(len-100)/len*0.1;

  }

}

void mouseDragged(){

  x=mouseX;

  y=mouseY;

}

貓追老鼠遊戲

圓球會追著滑鼠跑

void setup(){

  size(400,300);

}

float x=100,y=100;

void draw(){

  background(#002966);

  ellipse(x,y,50,50);

  if(! mousePressed ){

    float dx=x-mouseX;//target: mouse

    float dy=y-mouseY;

    float len=sqrt(dx*dx+dy*dy);

    x-=dx*0.1;

    y-=dy*0.1;

  }

}

保持100的距離

void setup(){

  size(400,300);

}

float x=100,y=100;

void draw(){

  background(#002966);

  ellipse(x,y,50,50);

  if(! mousePressed ){

    float dx=x-mouseX;//target: mouse

    float dy=y-mouseY;

    float len=sqrt(dx*dx+dy*dy);

    x-=dx*(len-100)/len*0.1;

    y-=dy*(len-100)/len*0.1;

  }

}

像彈簧一樣的樣子

if(! mousePressed ){
    
    float dx=x-200;
    float dy=y-150;
    float len=sqrt(dx*dx+dy*dy);
    float f=(len-100);
    dx/=len;
    dy/=len;
    vx-=f*dx*0.1;
    vy-=f*dy*0.1;
    x+=vx;
    y+=vy;

  }

----------------------------------------------------------------------------------------

把東西輸入txt中

#include <stdio.h>
int main(){
    FILE * fout=fopen("my_first_file.txt","w+");
    printf("Hello World");
    fprintf(fout,"Hello World");

}