Line/stroke fading issue

Programming Questions

jamesalli..

in Programming Questions • 1 year ago

Hi All

I recently went from using Processing 1.5.1 to 2.0 Beta 3 and have found a quirk in the P3D drawing.

I'm trying to leave trails when drawing graphics by not calling background() but drawing a low alpha rect() at the beginning of each draw function. This is a technique I've used many times without a problem but I'm finding that lines or ellipses/rects with strokes are not fading.

If you change the renderer to P2D this isn't a problem. The speed of P3D is required for this project.

Am I missing something? Are others finding the same issue?

James

void setup()
{
size(500, 500, P3D);
}
void draw()
{
pushMatrix();
//translate(200, 0, 1);
fill(222, 1);
rect(0, 0, width, height);
popMatrix();
fill(random(255), 24, 76);
ellipse(random(width), random(width), 30, 30);
line(random(width*0.5), random(height*0.5), random(width*0.5), random(height*0.5));
}

Replies(3)

PhiLho

Re: Line/stroke fading issue

1 year ago

" If you change the renderer to P2D this isn't a problem. The speed of P3D is required for this project."
Strange as P2D and P3D are supposed to behave similarly.
In 2.0, they are both backed up by OpenGL.

I just tried your sketch, on my system (Windows 7), they fade similarly in both modes.

jamesalli..

Re: Line/stroke fading issue

1 year ago

Thanks for getting back PhiLho. It seems the sketch I originally posted had an incorrect value for the rect alpha. New sketch below?

I'm using a 17 inch Macbook Pro with an NVIDIA GeForce 9400M 256MB graphics card.

This doesn't seem to be a problem on a PC.

void setup()
{
size(500, 500, P3D);
}
void draw()
{
pushMatrix();
fill(222, 5);
rect(0, 0, width, height);
popMatrix();
fill(random(255), 24, 76);
ellipse(random(width), random(width), 30, 30);
line(random(width*0.5), random(height*0.5), random(width*0.5), random(height*0.5));
}

srdjan.ma..

Re: Line/stroke fading issue

11 months ago

Help!

I am having the same problem here. Semi-transparent rect fades the line but it also leaves pale pink trail behind.
Problem is that I cant use P2D render because it crashes. It crashes everytime I put P2D, P3D, OPENGL in size(w,h).
I've tried every hint(...) in existance but I can't make lines to fade properly. This problem exists in 1.5.1 and 2.0b5.
I am using Win7Pro 64bit.

This simple code is the example of white semitrans rect not "fading" circle below properly(at least on my machine):

float ypos=0;
float inc=0.2;

void setup() {
size(800, 600);
background(255);
stroke(#FC7921, 22);
smooth();
rectMode(CENTER);
}

void draw() {
fill(255,11);
rect(400, 300, 800, 600);

noFill();
ellipse(400, ypos+=inc, 50, 50);

if(ypos > 600 || ypos < 0 ) inc=-inc;
}

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