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Index › Programming Questions & Help › OpenGL and 3D Libraries › gluSphere

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gluSphere (Read 2532 times)

manunu

gluSphere
Dec 4^th, 2006, 10:12pm

hey folks,

i want do draw a sphere with the glut framework. the jogl i already got and either i imported the libraries:

import javax.media.opengl.glu.*;
import javax.media.opengl.*;
import processing.opengl.*;

with the following code i wanted to draw my sphere:
GLU glu = new GLU();
GLUquadric qobj0 = glu.gluNewQuadric();
glu.gluSphere(qobj0, 1, 64, 64);

but it doesn't work. i get a GLexception like this:
javax.media.opengl.GLException: No OpenGL context current on this thread

.. and now i don't know any further? how can i work with gl and glu commands together?

for using "common" opengl commands the following is needed:
PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
GL gl = pgl.beginGL();
// my commands here
pgl.endGL();

and unfortunatelly GLU glu = pgl.beginGLU() doesn't work Sad

can anybody help me outta here?

thx in advance,
manunu

i like my coffee black and bitter 'cause it reminds me of my own life...

JohnG

Re: gluSphere
Reply #1 - Dec 5^th, 2006, 12:04am

You're creating your GL/GLU objects wrongly. one of each has already been created, and set-up properly when you call size(123 ,123 , OPENGL);, you just need to create a local variable to make access to it easier.

Code:

import processing.opengl.*;
import javax.media.opengl.*;
import javax.media.opengl.glu.*;

GL gl;
GLU glu;

void setup()
{
  size(800,600,OPENGL);
  gl=((PGraphicsOpenGL)g).gl;
  glu=((PGraphicsOpenGL)g).glu;
}

HOWEVER, and this is a big however, processing does some fiddling in between what you write, and what appears on screen, so it is NOT possible to simply run both processing commands and GL commands side by side, things will appear in the wrong places, look bad, and cause various other oddities. There are ways around it, but it's not easy.

manunu

Re: gluSphere
Reply #2 - Dec 5^th, 2006, 9:29am

thx for the fast help!
it kind of works now (don't get any more errors), but i'm not able to draw anything.

void setup()
{
size(800,400,OPENGL);
gl=((PGraphicsOpenGL)g).gl;
glu=((PGraphicsOpenGL)g).glu;
background (255);
}

void draw () {
GLUquadric qobj0 = glu.gluNewQuadric();
glu.gluSphere(qobj0, 1, 64, 64);
}

i just see my black background. do i have to declare some kind of block like i have to do with "common"opengl commands?
this thing here:
PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
GL gl = pgl.beginGL();
...
pgl.endGL();

? i'm really stuck... Sad

greets, manunu

i like my coffee black and bitter 'cause it reminds me of my own life...

JohnG

Re: gluSphere
Reply #3 - Dec 5^th, 2006, 10:58am

manunu wrote on Dec 5^th, 2006, 9:29am:

PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
GL gl = pgl.beginGL();
...
pgl.endGL();

I've no idea where you've got that above code from, but it's cmopletely wrong and it'll never work as none of those functions exist.

You can't just do pure GL/GLU functions in Processing. Processing does some munging behind the scenes that mean it wont work.

You may be able to do it if you find the ProGL library for Processing, but I've not used it so I'm not sure.

manunu YaBB Newbies Offline Posts: 4	Re: gluSphere Reply #4 - Dec 5^th, 2006, 11:43am the little code fragment above with the PGraphicsOpenGL thing is from the processing reference site, where the use of "gl." commandos is described. therefore i used this pgl.beginGl() and pgl.endGl() for "common" openGL commandos. so how can i get my glu.gluSphere(...) working? thx, manunu
	i like my coffee black and bitter 'cause it reminds me of my own life...

manunu

Re: gluSphere
Reply #5 - Dec 5^th, 2006, 12:01pm

problem solved...

my stupid sphere was always too small..
so that was/is the working code from my draw-method:

void draw () {

background(255);
PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
GL gl = pgl.beginGL();

GLUquadric qobj0 = glu.gluNewQuadric();
gl.glColor4f(0.7, 0.7, 0.7, 0.8);
gl.glTranslatef(width/2, height/2, 0);
glu.gluSphere(qobj0, 100, 64, 64);

pgl.endGL();
}

thx anyway for the help!

greets, manu

i like my coffee black and bitter 'cause it reminds me of my own life...

JohnG Ex Member	Re: gluSphere Reply #6 - Dec 5^th, 2006, 12:44pm Ah, I was confused since I think beginGL is a new feature of processing's that's not been advertised anywhere that I can tell. Looks useful though.

fry YaBB Moderator Offline Posts: 2623 mass, usa	Re: gluSphere Reply #7 - Dec 5^th, 2006, 1:58pm see advertisement in the reference: http://processing.org/reference/libraries/opengl/index.html

JohnG

Re: gluSphere
Reply #8 - Dec 5^th, 2006, 3:59pm

Ah so it is. That completely passed me by.

I know it says things will probably go wrong, and we shouldn't use processing as a java/GL tool, but it works fairly well. I stripped my custom GL library out of a sketch, changed a couple of things, and it seems to work very well. (though I do no processing based fcuntions, only GL ones)

( http://www.hardcorepawn.com/CowCatcher/ for anyone interested )

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