Trying to draw a line

Programming Questions

barlow011

in Programming Questions • 10 months ago

Hi,

I'm trying to draw a line...
I want a black, 1 pixel line in P3D. For example, with that simple code I get...a 2 pixel and gray line!!!!

void setup() {
size(600, 400, P3D);
background(255);
noSmooth();
strokeWeight(1);
stroke(0);
line(0, 200, 0, 600, 200, 0);
}

After try with 2 video cards and a lot of experiments I've learned that in Javascript mode it draws the line correctly, but in Java mode not. I'm using Windows 7 (64 bits).
Any idea/advice?
Anyone can draw a black, 1 pixel line in P3D? With wich hardware and software??? I'm going to buy the same...

Thanks!
d.

Replies(14)

PhiLho

Re: Trying to draw a line

10 months ago

Works for me, in Windows 7 too, with Processing 1.5.1...

barlow011

Re: Trying to draw a line

10 months ago

Hi!

Yes, I know...
For me, in 1.5.1 it works with P3D but not with OpenGL mode. I think that the problem is that with OpenGL some kind of smooth is enabled.
For you is it working in OpenGL mode too? How much do you want for your computer?? I really need a black, 1 pixel line... =D

thanks!
d.

mr.t

Re: Trying to draw a line

10 months ago

what's not working for you P3D or OPENGL. get a bit confused here ;)

but try

hint(DISABLE_OPENGL_2X_SMOOTH);

barlow011

Re: Trying to draw a line

10 months ago

Hi!

It's not working P3D in Processing 2.0. It makes me always some kind of smooth.
I can't draw a 1 pixel line or 1 pixel point!

I think that hint(DISABLE_OPENGL_2X_SMOOTH); is not working in Processing 2.0, isn't it?

In fact, in 1.5.1 it makes the same effect when I use OpenGL (I think that OpenGL in 1.5.1 = P3D in 2.0).
I tried hint(DISABLE_OPENGL_2X_SMOOTH); in 1.5.1 but nothing...

d.

mr.t

Re: Trying to draw a line

10 months ago

strange...

for me i have it all good on P 1.5.1 in P3D & OPENGL mode.

and in P 2a08 I have the same effect as you described but also for both modes! O.O

and yes. the hint of course wouldn't work with the alpha.

PhiLho

Re: Trying to draw a line

10 months ago

Indeed, P2D and P3D now use OpenGL. So rendering is highly dependent on the kind of graphics card you have, now...
And IIRC, OpenGL in 1.5 is v.1, while it is v.2 in 2.0. Perhaps it is also a source of differences.

mr.t, you build Processing from the source? Because 2.0b8 isn't visible yet in the list of downloads...

mr.t

Re: Trying to draw a line

10 months ago

no. actually i didn't .. as a7 is the latest release.. it must have been shortly there...and got removed again.. double checked and jep 2.0a8 :)

PhiLho

Re: Trying to draw a line

10 months ago

Uh, I regularly get confused by 2.0a vs. 2.0b.
I don't expect users to still use alpha versions...

barlow011

Re: Trying to draw a line

10 months ago

> Indeed, P2D and P3D now use OpenGL. So rendering is highly dependent on the kind of graphics card you have, now...

Yes, I was thinking that the problem was my graphic card (Nvidia GeForce GTX 560), but I bought an AMD FirePro V4900 yesterday and it makes the same! That's a professional video card for working with OpenGL, 3D, etc.

Which video cards are people using here? In fact, I think that maybe a lot of people are having that issue but they don't know...

PD: I tried with a MacBook too... nothing to do. I'll try later again with the 2.0b7

thanks!
d.

PhiLho

Re: Trying to draw a line

10 months ago

Alas, I am not an OpenGL specialist.
Perhaps try to increase the strokeWeight() value (perhaps even with fractional values like 1.5).
I don't know how lines are simulated in OpenGL, since they have, theoretically, no surface (unless they are tubes?). Playing with OpenGL hints can help, too.

barlow011

Re: Trying to draw a line

10 months ago

Hi,

That's really frustrating...
Then, PhiLho that code in P 2.0b7 (Java mode) draw you a 1 pixel and black line?

size(100, 100, P3D);
noSmooth();
line(0,50,100,50);

Could I know which video card are you using? I can't be buying a new video card every week...
Have you solved it in your computer mr. t?

Thanks a lot!!
d.

PhiLho

Re: Trying to draw a line

10 months ago

I finally tried your sketch in 1.5.1 in OpenGL mode, and in 2.0b7 in P3D and OpenGL modes, and all of them produced a black line.

Ah, scratch that. Almost black... Zooming in, I see it is #808080, so more gray than black. And it is two pixels wide. It is probably an effect of default lighting mode.
If I set strokeWeight() to 0.5, the line is 1 pixel wide. But still gray.

Not sure if you can attain your objective in 3D...

barlow011

Re: Trying to draw a line

10 months ago

hi!

Thanks for your test PhiLho! Well, then it's not me that I'm getting crazy. Good!
I think it's a big bug or something happens. strokeWeight(1) means 1 pixel, not 2... and stroke(0) means black, not almost black... in 2D or 3D.

Well, i t's a bit surprising... and frustrating.
let's continue finding a solution...

Thanks!
d.

barlow011

Re: Trying to draw a line

10 months ago

Well, definitely I think there's a bug here.
With that code... I get my 1 pixel line in P3D!!

void setup() {
size(600, 400, P3D);
noSmooth();
}

void draw() {
background(255);
line(400.1, 0, 400.1, 400);
}

The line must be in 400.1!!!!
With line(400, 0, 400, 400) I get nothing... any line. Only the background.

See you,
d.-

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