Processing 1.0 - Processing Discourse - OpenGL: low quality 2D graphics

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Index › Programming Questions & Help › OpenGL and 3D Libraries › OpenGL: low quality 2D graphics

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OpenGL: low quality 2D graphics (Read 1047 times)

andrew_r

OpenGL: low quality 2D graphics
Jan 13^th, 2006, 11:17am

Hi,

As designer exploring the potential of Processing I so have a sketchy knowledge of some of the technical concepts (so be gentle) .

I have been drawing simple lines which have worked OK, but when I add the OpenGL library the quality of the graphics becomes noticeably worse. Why is this happening: is there something I am missing, misunderstanding or misusing?

A simple example of this (below).

import processing.opengl.*;

float x ;
float y;
float angle;
float radius;
float w ;
float inc;

int timer = 0;
void setup () {
size (500, 500, OPENGL);
rectMode (CENTER);
smooth();
stroke (256, 256, 256);
strokeWeight (2.5);
noStroke ();
fill (0,0,0);
background (0, 50, 0);
reset ();
}

void draw () {
framerate (25);
scale (0.5);
if (timer % 5 == 0 ) {
fill (0, 50, 0, 10);
rect (250, 250, 500, 500);
}
fill (256,256,256);
translate (200, 0);
if (timer % 1 == 0) {
lineDraw (x, y, angle, radius);
}

if (w < 2 ) {
reset ();
}

timer ++;
}
void reset () {
x = 0;
y = 0;
angle = 60;
radius = 10;
w = 20;
inc = 1;
}
// input x and y into lineDraw and return the values as well
void lineDraw (float xpos, float ypos, float ang, float r) {
translate (xpos, ypos);
xpos = cos (radians (ang)) * r;
ypos = sin (radians (ang)) * r;
pushMatrix ();
rotate (radians (ang));
rect (0, 0, 8, w);
popMatrix ();
// x and y are the values fed into this function
// these values are used in the translate to be reset at 0, 0
// these values are increased each time.
x += xpos;
y += ypos;
angle += inc;
w -= 0.4;
// randomize the increment to randomize the direction of the line
inc+= random (-1, 1);

}

The sketch is much smoother when the OpenGL is not used .... why?

Thanks

Andrew

Ricard

Re: OpenGL: low quality 2D graphics
Reply #1 - Jan 13^th, 2006, 7:32pm

Hi there

nice applet!

I made a small modifications in order to allow the fading to affect the whole frame.

Code:


import processing.opengl.*;
 
float x ;
float y;
float angle;
float radius;
float w ;
float inc;
 
int timer = 0;
void setup () {
  size (500, 500, OPENGL);
  rectMode (CENTER);
  smooth();
  stroke (255, 255, 255);
  strokeWeight (2.5);
  noStroke ();
  fill (0,0,0);
  background (0, 50, 0);
  reset ();
}
 
void draw () {
  framerate (25);

  // Small modification here to enable the fading to affect all the frame
  // Scale afterwards

  if (timer % 5 == 0 ) {
    fill (0, 50, 0, 10);
    rect (width/2, height/2, width, height);
  }
  
  scale (0.5);
  
  fill (255,255,255);
  translate (200, 0);
  if (timer % 1 == 0) {
    lineDraw (x, y, angle, radius);
  }
 
  if (w < 2 ) {
    reset ();
  }
 
  timer ++;
}
void reset () {
  x = 0;
  y = 0;
  angle = 60;
  radius = 10;
  w = 20;
  inc = 1;
}
// input x and y into lineDraw and return the values as well
void lineDraw (float xpos, float ypos, float ang, float r) {
  translate (xpos, ypos);
  xpos = cos (radians (ang)) * r;
  ypos = sin (radians (ang)) * r;
  pushMatrix ();
  rotate (radians (ang));
  rect (0, 0, 8, w);
  popMatrix ();
  // x and y are the values fed into this function
  // these values are used in the translate to be reset at 0, 0
  // these values are increased each time.
  x += xpos;
  y += ypos;
  angle += inc;
  w -= 0.4;
  // randomize the increment to randomize the direction of the line
  inc+= random (-1, 1);
 
}

I agree that the OPENGL renderer works a little bit worse, this is filed as a bug:

http://dev.processing.org/bugs/show_bug.cgi?id=200

Is this what you meant

smallfly

Re: OpenGL: low quality 2D graphics
Reply #2 - Jan 14^th, 2006, 12:38am

I'm running the same applet by ART+COM and I have the same problem when openGL as graphic engine. But I'not sure this linked to the bug you are talking about. I mean, I moved other applet to openGL and I never got this result (poor quality).

They have another applet (named Garden) that runs better with openGL: smoother and better quality.
But I don't see the difference between the former one and Garden.

their URL:
http://www.artcom.de/process/

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