HTML5画布游戏射击子弹到鼠标点

HTML5 canvas game shoot bullet to mouse point.

本文关键字：子弹 射击 鼠标 游戏 布游戏 HTML5      更新时间：2023-09-26

现在。我把它设置成从我角色的方向射出子弹。但我希望能够将子弹射向鼠标点，让玩家更容易操作。

现在是

if(gun_1[i].direction == 2){ gun_1[i].x -= gun_1[i].speed * modifier};
if(gun_1[i].direction == 3){ gun_1[i].x += gun_1[i].speed * modifier};
if(gun_1[i].direction == 1){ gun_1[i].y -= gun_1[i].speed * modifier};
if(gun_1[i].direction == 4){ gun_1[i].y += gun_1[i].speed * modifier };
if(gun_1[i].direction == 5){ gun_1[i].y -= gun_1[i].speed * modifier; gun_1[i].x -= gun_1[i].speed * modifier };
if(gun_1[i].direction == 7){ gun_1[i].y += gun_1[i].speed * modifier; gun_1[i].x -= gun_1[i].speed * modifier };
if(gun_1[i].direction == 6){ gun_1[i].y -= gun_1[i].speed * modifier; gun_1[i].x += gun_1[i].speed * modifier };
if(gun_1[i].direction == 8){ gun_1[i].y += gun_1[i].speed * modifier; gun_1[i].x += gun_1[i].speed * modifier };

我希望能够拍摄到鼠标被点击的位置。如果可能的话。

当然，这并不难。但是你也可以做很多事情来改进你目前的设计。首先，添加velocityX和velocityY字段，这样在每一步中您只需要更新子弹的位置:

gun_1[i].x += gun_1[i].velocityX
gun_1[i].y += gun_1[i].velocityY

当按下鼠标时，设置子弹的速度:

canvas.onmousedown = function(e) {
   var dx = (e.x - character.x);
   var dy = (e.y - character.y);
   var mag = Math.sqrt(dx * dx + dy * dy);
   // whatever you need to do to get gun_1[i]
   gun_1[i].velocityX = (dx / mag) * speed;
   gun_1[i].velocityY = (dy / mag) * speed;
}

如果你对矢量略知一二我们只是将方向矢量归一化然后乘以标量初始速度。

另一个答案: 

gun_1[i].x += gun_1[i].velocityX;
gun_1[i].y += gun_1[i].velocityY;

var dx = (e.x - character.x);
var dy = (e.y - character.y);
var angle = Math.atan2(dy, dx);
gun_1[i].velocityX = Math.cos(angle) * speed;
gun_1[i].velocityY = Math.sin(angle) * speed;

   var i=0;
        var maxBullets=10;
        var allBullets=[];//a array for objects
        function bullet(){
           this.vx=0;
           this.vy=0;
           this.inix=0;
           this.iniy=0;
           this.angleGrads=0;
           this.angleRads=1.0;
           this.active=false;
        }
        bullet.prototype.exist=function(){
         //this.inix+=mathsin.bla,bla.bla.bla  bla
         if(this.x > wordWidth){
           //kill this bullet
           this.active=false;
          }
        }
        bullet.prototype.draw=function(){
          //ctx.draw bla, bla, bla 
        }
        function newBullets(){
          for(i=1;i<=maxBullets;i++){
            allBullets[i]=new bullet();
          }
        }
    function launchBullets(){
         for(i=1;i<=maxBullets;i++){
            if(!allBullets[i].active){
              //detemine angle with a point an the mouse point
              // math atan2()  ;)
              //asing values to this bullet
             allBullets[i].angleGrads=angleMouse;
             allBullets[i].inix=mousex;
             allBullets[i].iniy=mousey;
             allBullets[i].angleRads=(allBullets[i].angleGrads*PI)/180;
             //and end
             allBullets[i].active=true;
             //get out
             break;
            }
          }
    }//end of launchBullets
    function operations(){
      for(i=1;i<=maxBullets;i++){
            if(allBullets[i].active){
              allBullets[i].exist();
        }
      }
    }
    function paint(){
    for(i=1;i<=maxBullets;i++){
            if(allBullets[i].active){
              allBullets[i].draw();
        }
      }
    }//end of draw scene
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