What's matter with this drawing?

learner1

I try to draw a group of rays, like the following codes. I wish to see it acting as an animation, I add a delay 100ms in order to see the change rate and draw little by little, but even I reduce the delay to 1ms, the effect can not occur, it shows only black ground, and after long waiting, it shows all the picture suddenly, Im afraid it maybe caused by flush, I add a background bellow, but no use. what does it take place?

int width = 530, height = 600;
void setup() {      
    size(width, height);        
    smooth();      
    noStroke();    
    fill(200, 30, 200);  
   }
void draw() {     
   background(0);     
   for (int i = 0; i <= 120; ++i) {      
       for (int j = 0; j <= 120; ++j) {        
           float r = i*5;       
           float x = 230+r*cos(PI/30*j);       
           float y = 60+r*sin(PI/30*j);       
           ellipse(x, y, 3, 6); 
      delay(1); //even reduce to 1ms;
  //background(0);  //add herewith  
        }    
    }
}

dimkir

I refactored your code a bit and added some comments. Should help you understand better what's happening in your code:

int width = 530, height = 600;
void setup() {      
  size(width, height);        
  smooth();      
  noStroke();    
  fill(200, 30, 200);
}

void draw() {     
  thisFunctionCalled60TimesPerSecond();
}

void thisFunctionCalled60TimesPerSecond() {
  background(0);  // so you clear screen 60 times per second    
  // then this nested loop which results in 14400 iterations will 
  // be called 60 times per second
  for (int i = 0; i <= 120; ++i) {      
    for (int j = 0; j <= 120; ++j) {        
      float r = i*5;       
      float x = 230+r*cos(PI/30*j);       
      float y = 60+r*sin(PI/30*j);       
      ellipse(x, y, 3, 6);
     // this delay, because it is inside of nested loop,
     // inside of each frame will be executed 14000 times. 
     // resulting in 14second delay 
      delay(1); //even reduce to 1ms;  

      //background(0);  //add herewith
    }
  }
}  

GoToLoop

Consider draw() itself as a big loop. And you can control its FPS speed w/ frameRate().

_vk

also this might help understanding as well, then u can use frameRate() as GoToLoop said:

int width = 530, height = 600;
int i=0;
void setup() {      
  size(width, height);        
  smooth();      
  noStroke();    
  fill(200, 30, 200); 
  background(0);
}
void draw() {         
  for (int j = 0; j <= 120; ++j) {        
    float r = i*5;       
    float x = 230+r*cos(PI/30*j);       
    float y = 60+r*sin(PI/30*j);       
    ellipse(x, y, 3, 6); 
  }    
  i++;
}

learner1

Why does my pc look the code strange? all of them are in one line without any format. except different color to distinguish them. what's matter? I use xp os.

learner1

It seems browser's problem, I change chroma, then all is done. is it not fitting to ie?

learner1

dimkir, I may not understand what your saying, what's different from my origianl code? it seems all the same.

learner1

To All, could you explain why ellipse can be redrawed once a time in the circle?

for (int i = 0; i <= 120; ++i) {      
    for (int j = 0; j <= 120; ++j) {        
      float r = i*5;       
      float x = 230+r*cos(PI/30*j);       
      float y = 60+r*sin(PI/30*j);       
      ellipse(x, y, 3, 6); // why don't display once a cycle?
      //until all cycles are done.

      delay(1); //even reduce to 1ms;

This is what I want to know.

_vk

The difference are the comments... :)

_vk

Once execution goes inside a for loop, it loops until condition is met, and only then continues, Processing renders the frame to be displayed only as the last thing in draw. So when the display is rendered all iterations that draw all ellipses have already happen... check this out... It illustrates the rendering at the end of the draw, try comment out line 6...

void draw(){
  //background(80);//will work! and uncomment this
  fill(255,0,0);//red
  ellipse(random(width),random(height), 20, 20);
  println(frameCount); // I'm looping...
  background(80);//WRONG!! comment this out
}

learner1

well, look at this sample,

void setup() {
  //frameRate(4);//delete it here, instead of delay() below.
}
int pos = 0;
void draw() {
  background(204);
  pos++;
  line(pos, 20, pos, 80);  
  if (pos > width) {
    pos = 0;
  }
 delay(300); // it works well, as same as frameRate(),
}

at this example, the line draws very well each cycle, but above ellipse cannt be done.

learner1

void setup() {
  frameRate(4);
}
int pos = 0;
void draw() {
  background(204);
  pos++;
  line(pos, 20, pos, 80);
  if (pos > width) {
    pos = 0;
  }
}

-k-

_vk

Please format your code properly, no [code] tags, paste it, select it, and hit 'C' button above edit area. Or ident each line 4 spaces... :) I can't copy it like this. I remeber there is an article about this in wiki, with a much better explanation... here it is:

http://wiki.processing.org/w/I_display_images_in_sequence_but_I_see_only_the_last_one._Why?

_vk

There is no for loop () in this new code... If you add one...

void setup() { 
  frameRate(4);
} 
int pos = 0; 
void draw() { 
  background(204); 
  pos++; 
  line(pos, 20, pos, 80); 
  if (pos > width) { 
    pos = 0;
  }
  for(int i = 0; i < 10; i++){
    line(width-pos - i * 5 , 20, width-pos - i * 5, 80);
  }

}

you see, you cant see each line of the group, they are all draw at once

learner1

I hit "c" frequently and heavily :( , but nothing happened. I try to use code, but no use, either. what's matter?

learner1

-mmm- mmm mmmmmmm****mm code code well, only but this C can not paly a role, nor is cotr-k.

learner1

>

code well, only but >

this forum is odd enough to post. Im afraid I have to learn it again how to use it.

learner1

There is no for loop () in this new code>

draw() function itself is a loop, unless you use noLoop() in set up part.

GoToLoop

An alternative option for button C is use CTRL+K. :(|)

learner1

Nor is ctrl+k, as I said above, no use. nothing take place. what's matter? neither IE can do, nor chrome .

learner1

and it seems sometime entry can not act look up, it lines up in one line.

learner1

What I wonder is my top thread use code braket the code, it well done, but not the follow. what browser are you all using?

learner1

} for(int i = 0; i < 10; i++){ line(width-pos - i * 5 , 20, width-pos - i * 5, 80);//when this function excutes? } } you see, you cant see each line of the group, they are all draw at once

look my comment, when will the line() execute? as if the function when be in a local part will not draw in time in a cycle?

Im afraid this is what the problem is.

learner1

I think I can use a static variable to solve the problem.

learner1

and interest, when I finish to post, a error occurs and have to reflash to rewite to post, :(

_vk

about forum format:

http://forum.processing.org/two/discussion/32/how-to-format-text-and-code-on-the-new-forum#

when will the line() execute?

You can see that for your self :)

void setup() { 
  frameRate(1);
} 
int pos = 0; 
void draw() { 
  println("**********I'm frame " + frameCount + " begning to execute****************");
  background(204); 
  pos++; 
  line(pos, 20, pos, 80); 
  println("I just draw left line in this frame, but not rendered it yet\n");
  if (pos > width) { 
    pos = 0;
  }
  for (int i = 0; i < 10; i++) {
    println("This is the iteration number: " + i + " of the for loop begning to execute");
    line(width-pos - i * 5, 20, width-pos - i * 5, 80);
    println("I just draw right line number " + i +  " in this frame, but not rendered it yet\n");
  }

  println("***********   I'm frame " + frameCount + " ending to execute and rendering this frame to display  ********\n\n");
}

edit: maybe you should report formatting issue in the thread linked above

learner1

thank you , I understand what you aer saying. .