Processing 1.0 - Processing Discourse - Texture in 'pure' openGL

tarik

Texture in 'pure' openGL
Jan 3^rd, 2008, 11:24pm

Hi, I'm a big fan of talking directly to my graphics card because of the low-level control it gives me and generally that works just fine. But I do have a problem applying textures: I don't know how to get the data from a PImage type into my openGL code correctly.

I've tried stuff like:
...
PImage texmap;
...
texmap = loadImage("uitzicht.jpg");
intBuffer = IntBuffer.wrap(texmap.pixels[]);
...
gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, texmap.width, texmap.height, 0, gl.GL_RGBA, gl.GL_UNSIGNED_INT, intBuffer);
...

but the data inside my intbuffer doesn't seem to be configured correctly, somehow. Does somebody here know how to convert this data into a format that the glTexImage2D command understands?

Thanks to anyone who's even willing to think about this question!

JohnG

Re: Texture in 'pure' openGL
Reply #1 - Jan 4^th, 2008, 1:38am

If you don't need to access the texture info in a processing style, you can bypass the PImage level entirely, and go with something like:

Code:

import com.sun.opengl.util.texture.*;

Texture tex;

void setup()
{
  //... normal setup
  try
  {
    tex=TextureIO.newTexture(new File(dataPath("uitzicht.jpg")),true);
    tex.setTexParameteri(GL.GL_TEXTURE_WRAP_R,GL.GL_REPEAT);    
    tex.setTexParameteri(GL.GL_TEXTURE_WRAP_S,GL.GL_REPEAT);
    tex.setTexParameteri(GL.GL_TEXTURE_WRAP_T,GL.GL_REPEAT);
  }
  catch(Exception e)
  {
    println(e);
  }
}

void draw()
{
  // go into pure GL mode
  tex.bind();
  tex.enable();
  gl.glTexCoord2f(0,0); //0.0 -> 1.0 on both axes.
  gl.glVertex3f(0,0,0);
  //more texcoords/verts
  tex.disable();
  
}

Code unfortunately untested, but cribbed form a program I have that does use them so any errors should just be minor.

tarik YaBB Newbies Offline Posts: 16	Re: Texture in 'pure' openGL Reply #2 - Jan 11^th, 2008, 3:58pm Thanks a lot, that sure gives me a lot more possibilities to work with. I would still be very glad though if I could also do this with an PImage object (so I can, indeed, do some processing on the image beforehand) - T

antiplastik YaBB Moderator Offline Posts: 699 France	Re: Texture in 'pure' openGL Reply #3 - Jan 11^th, 2008, 8:25pm you can also instanciate a Texture using a java.awt.BufferedImage : TextureIO.newTexture(java.awt.BufferedImage image, boolean mipmap) that means, you just need to convert the PImage you're having fun with into a java.awt.BufferedImage

JohnG Ex Member	Re: Texture in 'pure' openGL Reply #4 - Jan 11^th, 2008, 8:45pm I believe that there is an internal BufferedImage within a PImage, though whether it's accessible is another matter.

ascorbin

Re: Texture in 'pure' openGL
Reply #5 - Jan 23^rd, 2008, 1:02pm

Here is my OPENGL / PImage bypass:

Code:


import processing.opengl.*;
import javax.media.opengl.*;
import com.sun.opengl.util.texture.*; 

Texture tex; 

void setup() 
{ 
  size(1200,800, OPENGL);
  try { tex=TextureIO.newTexture(new File(dataPath("red_circuit.png")),true); }
  catch(Exception e) { println(e); }
} 

void draw() 
{ 
  background(0);
  
  PGraphicsOpenGL pgl = (PGraphicsOpenGL) g; 
  GL gl = pgl.beginGL(); 

  tex.bind(); 
  tex.enable(); 

  gl.glBegin(GL.GL_QUADS);
  gl.glNormal3f( 0.0f, 0.0f, 1.0f);
  gl.glTexCoord2f(0, 0); gl.glVertex2f(0, 98);
  gl.glTexCoord2f(1, 0); gl.glVertex2f(251, 98);
  gl.glTexCoord2f(1, 1); gl.glVertex2f(251, 0);
  gl.glTexCoord2f(0, 1); gl.glVertex2f(0, 0);
  gl.glEnd();  

  tex.disable(); 

  pgl.endGL();
}

works, but why is Y flipped?

« Last Edit: Jan 28^th, 2008, 12:14am by ascorbin »

V Senior Member Offline Posts: 430 portugal	Re: Texture in 'pure' openGL Reply #6 - Jan 23^rd, 2008, 4:56pm it could be your texture set up to flip y, or it is just opengl that differs and works with a flipped y-axis simple use a a value to flip your texcoords or object mesh data
	Victor Martins \| www.pixelnerve.com/v

ascorbin

Re: Texture in 'pure' openGL
Reply #7 - Feb 1^st, 2008, 3:44pm

All right, works fine so far. But, the textureloader com.sun.opengl.util.texture converts my png with straight alpha into premultiplied alpha:

tex=TextureIO.newTexture(new File(dataPath("alpha_3.png")),true);

This makes a black halo effect. I know that I can blend it with:

gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);

instead of:

gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);

But when I use multiple Layers, which are also blended it looks strangly added. Hm, has anyone a link to a Textureloader which does no premultiply?

sorry for my bad english ascorbin

JohnG Ex Member	Re: Texture in 'pure' openGL Reply #8 - Feb 1^st, 2008, 5:25pm Unfortunately it's the Texture class that does the premultiply according to the documentation, so you'll have to load the image manually, and faff with lower level GL commands yourself to use it.

ascorbin

Re: Texture in 'pure' openGL
Reply #9 - Feb 1^st, 2008, 7:42pm

OK, I have it! Who ever will ever need this. Layer your premultiplied alpha pics with:

gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);

and then you can blend them with:

gl.glColor4f(alpha, alpha, alpha, alpha);

or stay in the normal mode an do:

gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
gl.glColor4f(1, 1, 1, alpha);

It took me some days to find this, I hope someone can use it.

sgsrules Full Member Offline Posts: 108 Texas	Re: Texture in 'pure' openGL Reply #10 - Apr 28^th, 2008, 5:36pm Instead of messing around with blend modes why not use TextureData instead of Texture? That way you don't have to worry about all the automatic stuff Texture does to your data. I know it might be a little more work since you have to generate mipmaps, filters et cetera, but at the end doesn't this give you more control?
	Stephen Shepard (sgsrules)

triscuit

Re: Texture in 'pure' openGL
Reply #11 - Apr 29^th, 2008, 1:26am

ascorbin wrote on Feb 1^st, 2008, 7:42pm:

OK, I have it! Who ever will ever need this. Layer your premultiplied alpha pics with:

gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);

and then you can blend them with:

gl.glColor4f(alpha, alpha, alpha, alpha);

or stay in the normal mode an do:

gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
gl.glColor4f(1, 1, 1, alpha);

It took me some days to find this, I hope someone can use it.

This sounds good. It would be amazing if you could post a complete example.

Xer

Re: Texture in 'pure' openGL
Reply #12 - Apr 29^th, 2008, 3:23pm

I have modified the code to the following. if I set the org_opengl to false, it seems fine; however, if I set the org_opengl to ture, the texture is distorted.

Is the processing bug???

Plz help

=======================================================
import processing.opengl.*;
import javax.media.opengl.*;
import com.sun.opengl.util.texture.*;
boolean org_opengl=true;

Texture tex;
PImage ti;
void setup()
{
size(480,320, OPENGL);
if(org_opengl)
{
ti = loadImage("test.png");
textureMode(NORMALIZED);
} else
{
try { tex=TextureIO.newTexture(new File(dataPath("test.png")),true); }
catch(Exception e) { println(e); }
}
}

void draw()
{
background(0);

// the texture size is 300x300
if(org_opengl)
{
beginShape();
texture(ti);
vertex(290, 160, 1, 0.5);
vertex(265, 205, 236.0/300.0, 1);
vertex(215, 205, 64.0/300.0, 1);
vertex(190, 160, 0, 0.5);
vertex(215, 115, 64.0/300.0, 0);
vertex(265, 115, 236.0/300.0, 0);
endShape();
} else
{
PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
GL gl = pgl.beginGL();

tex.bind();
tex.enable();

gl.glBegin(GL.GL_POLYGON);
gl.glNormal3f( 0.0f, 0.0f, 1.0f);
gl.glTexCoord2f(1, 0.5); gl.glVertex2f(290, 160);
gl.glTexCoord2f(236.0/300.0, 1); gl.glVertex2f(265, 205);
gl.glTexCoord2f(64.0/300.0, 1); gl.glVertex2f(215, 205);
gl.glTexCoord2f(0, 0.5); gl.glVertex2f(190, 160);
gl.glTexCoord2f(64.0/300.0, 0); gl.glVertex2f(215, 115);
gl.glTexCoord2f(236.0/300.0, 0); gl.glVertex2f(265, 115);
gl.glEnd();

tex.disable();

pgl.endGL();
}
}

Thx&&Xer

julapy

Re: Texture in 'pure' openGL
Reply #13 - May 2^nd, 2008, 12:33pm

ive stumbled upon a texture tutorial on the trusty NeHe site (http://nehe.gamedev.net/) while trying to work out a texture problem in processing.
i wanted to have full control over what commands were made to opengl and not worry about what was under the hood.

anyway i think ive arrived at nice solution that exposes all the opengl calls needed for creating and applying textures. its especially handy when you need to change any texture parameters.

here is link to a version adapted for processing.
http://www.julapy.com/processing/TextureTest.pde

triscuit

Re: Texture in 'pure' openGL
Reply #14 - May 2^nd, 2008, 11:14pm

julapy wrote on May 2^nd, 2008, 12:33pm:

ive stumbled upon a texture tutorial on the trusty NeHe site (http://nehe.gamedev.net/) while trying to work out a texture problem in processing.
i wanted to have full control over what commands were made to opengl and not worry about what was under the hood.

anyway i think ive arrived at nice solution that exposes all the opengl calls needed for creating and applying textures. its especially handy when you need to change any texture parameters.

here is link to a version adapted for processing.
http://www.julapy.com/processing/TextureTest.pde

This is some amazing code! Thank you.

Anyone have any ideas on how to make the texture transparent