Monday, May 9, 2016

HTML5 - Beginners - rectsoverlap example

<!DOCTYPE = html>
<html><body>
<canvas id="myCanvas" width="640" height="480" style="border:1px solid #d3d3d3;">
Use different browser.
</canvas>
<script>
    var c=document.getElementById("myCanvas");
    var ctx=c.getContext("2d");
    
    var player = {
        x:10,
        y:10,
        w:32,
        h:32,
    };
    
    var enemy = {
        x:100,
        y:100,
        w:100,
        h:100,
    };
    
    gameloop=setInterval(dogameloop,16);
    
    function dogameloop(){
        ctx.clearRect(0,0,c.width,c.height);
        ctx.fillStyle="black";
        ctx.font="30px Arial";
        ctx.fillRect(player.x,player.y,player.w,player.h);
        ctx.fillRect(enemy.x,enemy.y,enemy.w,enemy.h);
        
        if (rectsoverlap(    player.x,player.y,player.w,player.h,
                            enemy.x,enemy.y,enemy.w,enemy.h)){
            ctx.fillText("Collision",30,30);
        }
                            
    }    
    
    
    document.onmousemove = function(mouse){
        player.x = mouse.clientX;
        player.y = mouse.clientY;
    }
    
    function rectsoverlap(x1,y1,w1,h1,x2,y2,w2,h2){
        return     x1 <= x2+w2
            &&     x2 <= x1+w1
            &&    y1 <= y2+h2
            &&    y2 <= y1+h1;
    }
    
    
    </script></body></html>

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