Can I move a point from one position to another without refreshing background in Draw()?

General Discussion Other

fari

Can I move a point from one position to another without refreshing background in Draw()?

in General Discussion • Other • 3 months ago

I am displaying tweets on a static map. The tweets are plotted over time on the map, so I don't set any background color in the Draw() method. Otherwise it will refresh the screen and plotted points will disappear.

However, I want to move a small circle from one location to another (based on plotted tweets) without drawing a line. Is there anyway to do so without setting background in the Draw()?

Replies(4)

PhiLho

Re: Can I move a point from one position to another without refreshing background in Draw()?

3 months ago

Duplicate with answers you did in (at least) another thread. Since I cannot answer to your comments, I just removed them...

The usual way of updating the display in Processing is to redraw the whole sketch area on each draw() call.
Why you don't want to do it this way? Performance reason?
At worst, you can use the old way used in video games in the times performances were very low: save the portion of background around the area where you will draw your marker, draw it, then on next frame, restore the portion of background and repeat for the new place.
Not sure if it is worth the trouble.

fari

Re: Re: Can I move a point from one position to another without refreshing background in Draw()?

3 months ago

Thanks! I was worried about performance (the sketch is listening to streaming API from twitter). But I don't have any other choice. I will try how effective the 'old game style' is.

curoiusbr..

Re: Can I move a point from one position to another without refreshing background in Draw()?

3 months ago

Use PG graphics and draw another transparent layer and refresh it.

http://processing.org/reference/PGraphics.html

PGraphics pg;

void setup() {
  size(100, 100);
  pg = createGraphics(40, 40);
}

void draw() {
  pg.beginDraw();
  pg.background(100,50);// pg.background(BG_color,Alpha);
  pg.stroke(255);
  pg.line(20, 20, mouseX, mouseY);
  pg.endDraw();
  image(pg, 9, 30); 
  image(pg, 51, 30);
}

PhiLho

Re: Can I move a point from one position to another without refreshing background in Draw()?

3 months ago

Don't worry about performance: try, and optimize only if performance is poor!
Drawing a background image should not be so slow, unless you have a very large sketch, perhaps.

Top Reply