hit a brick wall here - there must be a simple solution! Im working on a reacivision/reactable setup. i want objects which are placed on the table to be illuminated by a circle of light around their base, and with information about their ID, position and angle off to the side.

however, i want the pad/circle of light to fade so that you can see where the objects have been as they are moved around the table...while the information text needs to be refreshed for every frame without fading so they can be clearly read...

hope thats clear! the problem is that with drawing black boxes or similar around the text every frame to get rid of the old info - it also trapples right over the tails of the fading circles, and they gradually accumulate coverling the screen with permanent squares....

maybe im missing s trick here, i just want to refresh the text image every frame! here is the relevant code:

Quote:


i'm quite new to processing - i hope ive clearly described the problem...and i hope i've jsut missed something simple..

thanks in advance for any help,
FJ

thanks for the quick reply...

yeah, i had seen that post, it is a similar problem, but in that script the non-fading shapes just keep piling up, eventually you're left with a red screen...

what i need is exactly like the post you linked to, but where there is only ever one rectangle present on the screen....

still banging my head....

i've been trying that, with a couple of buffers, but i get one of two results:

either the rectangle fades too, or they stay permanently....

i think the problem is that the first thing i do with every draw() iteration is:

fill(100,5);
rect(0,0,width,height);

which gives me the fading, but also fades the rectangle depending on when i draw the buffer.....

...?

The method of using a second buffer:

Code:

float angle,speed;
PGraphics buffer;
PGraphics bufferCircle;

void setup(){

 size(400,400);
 noStroke();
 speed=0.04;
 loop();
 smooth();

 buffer = createGraphics(width, height, P2D); 
 bufferCircle = createGraphics(width, height, P2D);

}
void draw(){
 bufferCircle.beginDraw();
 bufferCircle.fill(20,5);
 bufferCircle.noStroke();
 bufferCircle.rect(0,0,width,height);

 angle+=speed;

 float X=width/2+sin(angle)*width/2;
 float Y=height/2+cos(angle)*width/3;

 bufferCircle.stroke(255);
 int rad=height/6;
 bufferCircle.ellipse(X,Y,width/8,height/8);
 bufferCircle.endDraw();

 buffer.beginDraw();
 buffer.background(0, 0);
 buffer.stroke(255);
 buffer.noFill();
 buffer.rect(X/2,Y/2,width/8,height/8);
 buffer.endDraw();

 image(bufferCircle,0,0);
 image(buffer,0,0);

}