The Essential Guide to HTML5

(Greg DeLong) #1

CANNONBALL AND SL INGSHOT


Code Explanation


}


function drawall() {


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


var i;


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


var ob = everything[i]; Extract array for object


if (ob[1]) { Need to translate and rotate?


ctx.save(); Save original axes


ctx.translate(ob[3],ob[4]); Do indicated translation


ctx.rotate(ob[2]); Do indicated rotation


ctx.translate(-ob[3],-ob[4]); Translate back


ob[0].draw(); Draw objec t


ctx.restore(); } Restore axes


else { Else (no rotation)


ob[0].draw();} Do drawing


} Close for loop


} Close function


function change() {


var dx = horvelocity;


verticalvel2 =verticalvel1 + gravity;


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

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