Canvas Games: Part I - HTML5 Canvas - page 661

var var y = 50 ;

var

var facingX = 0 ;
var

var facingY = 0 ;
var

var movingX = 0 ;
var var movingY = 0 ;

var var width = 20 ;

var

var height = 20 ;
var var rotationalVelocity = 5 ; //how many degrees to turn the ship

var

var thrustAcceleration = . 03 ;
var

var keyPressList = [];
function

function drawScreen () {

//check keys

iif ( keyPressList [ 38 ] == true true ){

//thrust
var var angleInRadians = rotation * Math . PI / 180 ;

facingX = Math . cos ( angleInRadians );
facingY = Math . sin ( angleInRadians );

movingX = movingX + thrustAcceleration * facingX ;
movingY = movingY + thrustAcceleration * facingY ;

}

iif ( keyPressList [ 37 ] == true true ) {

//rotate counterclockwise
rotation -= rotationalVelocity ;

}

iif ( keyPressList [ 39 ] == true true ) {

//rotate clockwise
rotation += rotationalVelocity ;;
} x = x + movingX ;
y = y + movingY ;

// draw background and text
context . fillStyle = '#000000' ;
context . fillRect ( 0 , 0 , 200 , 200 );
context . fillStyle = '#ffffff' ;
context . font = '20px sans-serif' ;
context . textBaseline = 'top' ;
context . fillText ( "Player Ship - key turn" , 0 , 180 );

//transformation
var

var angleInRadians = rotation * Math . PI / 180 ;