Cannonball and Slingshot - The Essential Guide to HTML5 - page 138

Code Explanation

drawall();

tid = setInterval(change,100);

}

}

function drawall() {

ctx.clearRect(0,0,cwidth,cheight);

var i;

for (i=0;i<everything.length;i++) {

everything[i].draw();

}

}

function change() {

var dx = horvelocity;

verticalvel2 = verticalvel1 + gravity;

var dy = (verticalvel1 +
verticalvel2)*.5;

verticalvel1 = verticalvel2;

cball.moveit(dx,dy);

var bx = cball.sx;

var by = cball.sy;

if ((bx>=target.sx+40)&&(bx<=
(target.sx+target.swidth-40))&&
(by>=target.sy+40)&&(by<=
(target.sy+target.sheight-40))) {

Check for inside of target (40 pixels)