Combining Bitmaps and Sound - HTML5 Canvas - page 488

context.save(); //save current state in stack
var sourceX = Math.floor(0 % 4) * tempSaucerMissile.width;
var sourceY = Math.floor(0 / 4) * tempSaucerMissile.height;
context.drawImage(particleTiles, sourceX, sourceY,
tempSaucerMissile.width,tempSaucerMissile.height,
tempSaucerMissile.x,tempSaucerMissile.y,tempSaucerMissile.width,
tempSaucerMissile.height);
context.restore(); //pop old state on to screen
}
}
function renderParticles() {
var tempParticle = {};
var particleLength = particles.length-1;
for (var particleCtr=particleLength;particleCtr>=0;particleCtr--){
tempParticle = particles[particleCtr];
context.save(); //save current state in stack
var tile;
//console.log("part type=" + tempParticle.type)
switch(tempParticle.type){
case 0: // saucer
tile = 0;
break;
case 1: //large rock
tile = 2
break;
case 2: //medium rock
tile = 3;
break;
case 3: //small rock
tile = 0;
break;
case 4: //player
tile = 1;
break;
}
var sourceX = Math.floor(tile % 4) * tempParticle.width;
var sourceY = Math.floor(tile / 4) * tempParticle.height;
context.drawImage(particleTiles, sourceX, sourceY,
tempParticle.width,tempParticle.height,tempParticle.x,
tempParticle.y,tempParticle.width,tempParticle.height);
context.restore(); //pop old state on to screen
}
}