The Essential Guide to HTML5

CANNONBALL AND SL INGSHOT

Code Explanation

var target = new Myrectangle(300,100,

80,200,"rgb(0,5,90)");

Build a Myrectangle object and assign to target

var ground = new Myrectangle(0,300,

600,30,"rgb(10,250,0)");

Build a Myrectangle object and assign to ground

everything.push(target); Add target to everything

everything.push(ground); Add ground

everything.push(cball); Add cball (which will be drawn last, so on top of other
stuff

function init(){ Header for init function

ctx = document.getElementById

('canvas').getContext('2d');

Set up ctx in order to draw on the canvas

drawall(); Draw everything

} Close init

function fire() { Head for fire function

cball.sx = iballx; Reposition cball in x

cball.sy = ibally; Reposition cball in y

horvelocity = Number(document.

f.hv.value);

Set horizontal velocity from form. Make a number

verticalvel1 = Number(document.

f.vv.value);

Set initial vertical velocity from form

drawall(); Draw everything

tid = setInterval

(change,100);

Start timing event

return false; Return false to prevent refresh of HTML page

} Close function