Processing: Rendering stops when delay function used - processing

Question

I created a simple delay function for my sketch and tried to use it, but it seems as if the rendering stops i.e., there is simple a grey screen and then everything is rendered all at once.
Could someone please tell me where I am going wrong? What exactly is happening?
Also how are draw() and setup() defined internally? I understand that setup() is a one time render and draw() like an infinite loop.
Code:
void delay(int delay)
{
int time = millis();
while(millis() - time <= delay);
}
void setup(){
size(600,400);
smooth();
}
void draw(){
background(0); //black
delay(1000);
fill(255); //white
ellipse(width/2, height/2, 300, 300);
delay(1000);
}

Answer 1

Also how are draw() and setup() defined internally? I understand that setup() is a one time render >and draw() like an infinite loop.
The thing is that draw() only renders a frame at the end of each execution, so stoping it is usually not a good idea.
http://wiki.processing.org/w/I_display_images_in_sequence_but_I_see_only_the_last_one._Why%3F
If you want to time things use booleans as flags for when things should happen.
check those also:
http://wiki.processing.org/w/What_are_setup()_and_draw()%3F
http://wiki.processing.org/w/How_do_I_display_a_message_for_a_few_seconds%3F

Answer 2

If you want delay, use a Thread() object, like the following code, to run the delays in a separate thread:
void delay(int delay)
{
try
{
Thread.sleep(delay);
}
catch(Exception EX)
{
}
}
void setup(){
size(600,400);
smooth();
thread("sleepy"); // the function sleepy will be started in a new thread
}
void draw(){
// draw() does nothing here except refresh the screen
}
void sleepy()
{
while(true)
{
background(0); //black
delay(1000);
fill(255); //white
ellipse(width/2, height/2, 300, 300);
delay(1000);
}
}
Additionally, the above delay method, Thread.sleep(), does not consume an entire CPU core as it runs (The millis() method is akin to a temporary infinite loop).
Tested on Processing 2.2.1, Windows 7 professional.