How to clear the screen after drawing something

knightmet..

How to clear the screen after drawing something

in Processing with Other Languages • 2 years ago

Hello,

I wrote a program that graphs voltages in real time coming from an accelerometer which then are looped every time they go all the way across the screen. The problem is that when the loop happens, the lines that represent the voltages remain where they are, that is, they start over again but overlapping the voltages in previous loops. In the end the screen gets pretty busy with lines on top of other lines which makes everything really messy.

I could copy and past my code but there are things that don't belong to Processing, at this point I'm only working from Java but using the Processing package, so the code has unfamiliar things to the Processing syntax. A guy from this forum helped with a previous problem I had in this program, he helped me out with this, which is the basic principle:

[code]

int a;
int sec;
int olda = 0;
int oldsec = second();
void setup() {
background(102);
size(500, 500);
}
void draw() {
a+=1;
sec = second();
line(olda, oldsec*4, a, sec*4);
olda = a;
oldsec = sec;
}
[/code]

How can I clear the screen so that when the lines reach the width of the screen they dissapear and then appear right at the beginning?

Thanks in advance.

Replies(2)

v.k.

Re: How to clear the screen after drawing something

2 years ago

just call background(yourBgColor);

at the beginning of draw() whenever u need to clean the screen. If you just call it at beginning it will refresh the window each draw() loop. You can obviously set a condition so it is called when u need. Alternatively you can draw a rect(0,0,width,height) using an "alpha" value to fade stuff over time. Calling fill(someRvalue,someGvalue,someBvalue,someLowAlphaValue) before rect. Note that if you call it (either rect or background) at the end of draw() loop u will see nothing as it going to cover your previous draws.

hope that help.

knightmet..

Re: Re: How to clear the screen after drawing something

2 years ago

v.lo_ol thanks a lot, that was easy :P

The logic was pretty obvious but for reason I thought it was harder.

Cheers.

Top Reply