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我正在尝试用上、下、左、右键控制一个椭圆。我想让它平滑，所以椭圆不会立即停止。此外，当它向左移动并按下右箭头时，它会更快地转身。

最小、完整和可验证的示例：

var x,y,speed,xspeed,yspeed,size;

function setup() {
createCanvas(window.innerWidth-20,window.innerHeight-20);
x = width / 2;
y = height - 20;
speed = 5.5;
yspeed = 0;
xspeed = 0;
size = 20;
}

function draw() {
background(0);
fill(255,0,0);
ellipse(x-size/2,y-size/2,size,size);
checkKeys();

x=constrain(xspeed+x,0+size,width);
y=constrain(yspeed+y,0+size,height);
}


function accelerateUP() {
  if(-1*(speed) <= yspeed && yspeed<= 0){yspeed-=0.5;}
  else if (0 < yspeed) yspeed=lerp(yspeed,0,0.5);
}
function accelerateDOWN(){
  if(yspeed >=0 && yspeed <= speed){yspeed+=0.5;}
  else if (yspeed <0) yspeed=lerp(yspeed,0,0.5);
}
function accelerateLEFT(){
  if(xspeed <=0 && xspeed >= -1*(speed)){xspeed-=0.5;}
  else if (xspeed >0) xspeed=lerp(xspeed,0,0.5);
}
function  accelerateRIGHT (){
  if(speed >= xspeed && xspeed >=0){xspeed+=0.5;}
  else if (0  > xspeed ) xspeed=lerp(xspeed,0,0.5);
}



function checkKeys (){

   if (keyIsDown(UP_ARROW)){
    accelerateUP();
   }          
   else if (keyIsDown(DOWN_ARROW)){
     this.accelerateDOWN(); 
   }else yspeed = lerp(yspeed,0,0.5);


   if (keyIsDown(LEFT_ARROW)){
     this.accelerateLEFT();
   }    
  else if (keyIsDown(RIGHT_ARROW)){
     accelerateRIGHT();
   }else
   xspeed = lerp(xspeed,0,0.5); 

 }
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1 回答 1

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Lerp 可能不适合这个，我找到了一种编码方法，它足够接近。如果您有更好的方法，请发表评论。我对此有点陌生，所以不要抨击我的代码。

var x, y, speed, xspeed, yspeed, size;

function setup() {
  createCanvas(window.innerWidth-20, window.innerHeight-20);
  x = width / 2;
  y = height - 20;
  speed = 7;
  yspeed = 0;
  xspeed = 0;
  size = 20;
}

function draw() {

  background(0);
  fill(255, 0, 0);
  ellipse(x-size/2, y-size/2, size, size);
  checkKeys();

  x=constrain(xspeed+x, 0+size, width);
  y=constrain(yspeed+y, 0+size, height);
}

function accelerateUP () {
  if (-1*(speed) <= yspeed && yspeed<= 0) {
    yspeed-=0.5;
  } else if (0 < yspeed) {  
    this.yspeed*=0.8; 
    if (-0.2 <yspeed && 0.2  > yspeed) yspeed =0;
  }
}

function accelerateDOWN() {
  if (yspeed >=0 && yspeed <= speed) {
    this.yspeed+=0.5;
  } else if (yspeed <0) { 
    yspeed*=0.8; 
    if (-0.2 <yspeed && 0.2  > yspeed) yspeed =0;
  }
}

function accelerateLEFT() {
  if (xspeed <=0 && xspeed >= -1*(speed)) {
    xspeed-=0.5;
  } else if (xspeed >0) { 
    xspeed*=0.8; 
    if (-0.2 <xspeed && 0.2  > xspeed) xspeed =0;
  }
}

function accelerateRIGHT() {
  if (speed >= xspeed && xspeed >=0) {
    xspeed+=0.5;
  } else if (0  > xspeed ) { 
    xspeed*=0.8; 
    if (-0.2 <xspeed && 0.2  > xspeed) xspeed =0;
  }
}



function checkKeys() {

  if (keyIsDown(UP_ARROW)) {
    accelerateUP();
  } else
    if (keyIsDown(DOWN_ARROW)) {
      accelerateDOWN();
    } else if (yspeed !=0) {
      if (yspeed > 0.2 || yspeed < -0.2)  yspeed*=0.9;
      else yspeed = 0;
    }



  if (keyIsDown(LEFT_ARROW)) {
    accelerateLEFT();
  } else
    if (keyIsDown(RIGHT_ARROW)) {
      accelerateRIGHT();
    } else if (xspeed !=0) {
      if (xspeed > 0.2 || xspeed < -0.2)  xspeed*=0.9; 
      else xspeed =0;
    }
};
于 2018-03-18T16:37:26.577 回答