Processing 1.0 - Processing Discourse - bouncing blocks, getting rid of tail effect

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Index › Programming Questions & Help › Programs › bouncing blocks, getting rid of tail effect

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bouncing blocks, getting rid of tail effect (Read 605 times)

M.J.

bouncing blocks, getting rid of tail effect
Oct 24^th, 2009, 10:06am

Hi there,

I'm having trouble getting rid of the tail effect on the blocks. Please can you help me. I'm enclosing the code below.
Thanks,
MJ

int numBlocks = 10; // declare the number of blocks to ten
Block[] blocks = new Block[numBlocks]; // declare and create array
ChangeColors c = new ChangeColors();

void setup() {
size(200,200);
smooth();
noStroke();

for(int i = 0; i < blocks.length; i++) {
float x = 10 + i*16;
float rate = 0.5 + i*0.05;
blocks[i] = new Block(x,50,16,rate); // create each objects
}
}

void draw() {
fill(0, 15); // color and opacity
rect(0, 0, width, height);
fill(255);
for(int i = 0; i < blocks.length; i++) {
blocks[i].move();
blocks[i].display();
c.changeColors(); // changes the color of the blocks
}
}

class Block {
float x,y,sz; //for rect
float sp; //speed
int pos=1; //position (direction)

Block(float xpos, float ypos, float area, float speed) {
x=xpos;
y=ypos;
sz=area;
sp=speed;
}

void move() {
y+=(sp*pos);
if ((y > (height - sz/2)) || (y < sz/2)) {
pos *= -1;
}
}

void display() {
rect(x,y,sz,sz);
}
}

class ChangeColors {

ChangeColors() {}
void changeColors() {
fill(random(0,255),random(0,255),random(0,255),random(0,255));
}
}

ChristianT

Re: bouncing blocks, getting rid of tail effect
Reply #1 - Oct 24^th, 2009, 10:25am

You start each frame by drawing a semi-transparent black panel:
fill(0, 15); // color and opacity rect(0, 0, width, height);
Of course, this is not making everything from the last frame disappear completely, thus leaving trails.

Try setting a non-transparent black:
fill(0, 255);
Or, since the rectangle fills the whole display anyway, replace both lines with:
background(0);

PhiLho

Re: bouncing blocks, getting rid of tail effect
Reply #2 - Oct 25^th, 2009, 1:42am

When I asked to remove the duplicate post in the other thread, I meant the one without answers...

I will remove my orphan answer to remove all trace of the old thread now, for the record I answered something similar to Christian's answer (which is more detailed).
"Replace your background with transparency (the fill+rect) lines, with a good old background() call."

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