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Index › Programming Questions & Help › OpenGL and 3D Libraries › Camera Problem using PGraphicsOpenGL and Blend
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Camera Problem using PGraphicsOpenGL and Blend (Read 1314 times)
Danny
Camera Problem using PGraphicsOpenGL and Blend
Aug 24th, 2007, 10:53am  
Hi there,

I'm having a problem with a sketch once I start using OpenGL like this:

import javax.media.opengl.*;

void draw(){
PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;  // g may change
GL gl = pgl.beginGL();  // always use the GL object returned by beginGL
 
gl.glDisable(GL.GL_DEPTH_TEST);
gl.glEnable(GL.GL_BLEND);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE);

MORE CODE
...

pgl.endGL();
}


So everything works, but the camera isn't looking at the same point any more as it does without that piece of code. I assume that the camera works different once I use the OpenGL object but I don't really know how.

I'm using a camera class and this is super simple code that also works fine with "normal" OpenGL Processing:

camera(this.posX, this.posY, this.posZ, // eyeX, eyeY, eyeZ
      this.targetX, this.targetY, this.targetZ, // centerX, centerY, centerZ
      0.0, 1.0, 0.0); // upX, upY, upZ

So any idea or help would be very appreciated!
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V
Re: Camera Problem using PGraphicsOpenGL and Blend
Reply #1 - Aug 24th, 2007, 12:27pm  
you shouldnt call camera() within beginGL and endGL..
here's your sample code with a test scene.. some random positioned boxes and a rotating camera around y-axis




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


void setup()
{
 size( 400, 400, OPENGL );
}

void draw()
{
 float time = millis() * 0.001;
 
 background( 0 );
 
 camera( sin(time*0.4)*50, 0, cos(time*0.3)*50,
         0, 0, 0,
         0, 1, 0 );
       
 PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
 GL gl = pgl.beginGL();
   
 gl.glDisable(GL.GL_DEPTH_TEST);
 gl.glEnable(GL.GL_BLEND);
 gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE);

 pgl.endGL();

 for( int i=0; i<60; i++ )
 {
   fill( i*100 );
   pushMatrix();
   translate( random(i*5), random(i*10), random(i*8) );
   box( 10 );
   popMatrix();
 }
}
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Victor Martins | www.pixelnerve.com/v
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JohnG
Re: Camera Problem using PGraphicsOpenGL and Blend
Reply #2 - Aug 24th, 2007, 1:19pm  
You can maybe use the glu version of camera:

Code:
import javax.media.opengl.glu.*;

//...

GLU glu=g.glu;
glu.gluLookAt(/*same options as for camera*/);
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V
Re: Camera Problem using PGraphicsOpenGL and Blend
Reply #3 - Aug 24th, 2007, 4:14pm  
ofcourse, if wanting to use opengl calls.
that might be what camera() does. its up to the programmer
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Victor Martins | www.pixelnerve.com/v
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Danny
Re: Camera Problem using PGraphicsOpenGL and Blend
Reply #4 - Aug 24th, 2007, 5:21pm  
Thanks for the fast reply everyone!
The simple solution by crmx already solved the problem! I assumed having no drawing commands between pgl.beginGL(); and pgl.endGL(); would be a problem, but it seems as if it wouldn't affect the drawing at all.

Will post a preview when I'm done, thanks again!
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