See http://dev.processing.org/bugs/show_bug.cgi?id=468 .

Long story short, this is a bug, should be fixed in one of the next releases, and can be sort of hacked around by using P3D in your size() statement but JAVA2D in the createGraphics() statement.  I'm not entirely sure if everything will work right using that hack, but things are at least slightly less broken in my experience.

ahh! thanks! - should have read the prev. posts more carefully!

so, i've got this working now:

Code:

PImage pattern;
PGraphics canvas;

void setup(){
  size(200, 200);
  pattern = loadImage("a_pattern.jpg");
  canvas = createGraphics(160, 160, JAVA2D);
  canvas.noStroke();
  canvas.tint(255);
}

void draw(){
  background(200, 80, 0);
  image(pattern, 5, 5);
  
  updateCanvas();
  image(canvas, 20, 20);
}

void updateCanvas(){
  canvas.beginDraw();
  //canvas.loadPixels(); // need this if P3D is set in size()
  canvas.background(33, 125, 180);
  canvas.image(pattern, mouseX-20, mouseY-20);
  canvas.modified = true; 
  canvas.endDraw();
}
 

...but - unfortunately this doesn't quite solve my problem. I failed to mention that size() needs to be OPENGL since I am using some GL_ stuff in my app.

modifying the code above to use OPENGL causes this error:
java.lang.ClassCastException: processing.opengl.PGraphicsOpenGL$ImageCache

code looks like this:
Code:

import processing.opengl.*;

PImage pattern;
PGraphics canvas;

void setup(){
  size(200, 200, OPENGL);
  pattern = loadImage("a_pattern.jpg");
  canvas = createGraphics(160, 160, JAVA2D);
  canvas.noStroke();
  canvas.tint(255);
}

void draw(){
  background(200, 80, 0);
  image(pattern, 5, 5);
  
  updateCanvas();
  image(canvas, 20, 20);
}

void updateCanvas(){
  canvas.beginDraw();
  //canvas.loadPixels(); // need this if P3D is set in size()
  canvas.background(33, 125, 180);
  canvas.image(pattern, mouseX-20, mouseY-20);
  canvas.modified = true; 
  canvas.endDraw();
}
 

...seems like OPENGL and JAVA2D doesn't like each other much!

any ideas/suggestions/links?

+ m

Ben! - thanks, it's good to be back, will make an effort to hang around the boards a bit more now (somehow 2 years went by between this and my last thread!) yikes!

i'm not sure i understand what you mean by using loadImage() twice.

I want to have a PGraphics in memory where I blend some images at runtime - then I want to read values (using get()) from the PGraphics object and use it to control some objects in my visible openGL environment.

Since there's no PGraphics.loadImage() function, how would I load images into JAVA2D to use there, and then, is there any way at all for the main program to read values from here and render them with openGL?

Sorry if I'm a bit slow (and keep rephrasing the question). Let me know if I'm chasing a red herring and I'll figure out another way to get my system working.

Cheers,
mikkel

yup - makes sense - but, it still doesn't solve my problem.

i can draw into a PGraphics(JAVA2D) object just fine, but I can't use this PGraphics object in openGL (as a texture for example).

my problem was less about using the same graphic in two different renderers - and more about getting bitmaps into PGraphics and thereafter PGraphics into openGL.

+ m

sweet!... thanks ben! you just saved me the better part of a day (was about to have to re-write a whole bunch of stuff on my current project).

in the interest of documenting the final working version, here's the code (v. 0124):

Code:

import processing.opengl.*;
PImage pattern;
PGraphics canvas;

void setup(){
  size(200, 200, OPENGL); 
  canvas = createGraphics(160, 160, JAVA2D);
  canvas.smooth();
  
  pattern = loadImage("a_pattern.jpg");
}

void draw(){
  background(200, 80, 0);
  updateCanvas();
  image(canvas, 20, 20);
}

void updateCanvas(){
  canvas.beginDraw();
  canvas.background(33, 125, 180);
  
  // bitmaps work!
  canvas.image(pattern, mouseX-20, mouseY-20);
  
  // drawing works!
  canvas.stroke(255);
  canvas.strokeWeight(3.0);
  canvas.noFill();
  canvas.ellipse(mouseX-20, mouseY-20, 50, 50);
  
  // use these for now to force it to work! (v. 0124)
  canvas.modified = true; 
  canvas.loadPixels();
  
  canvas.endDraw();
}
 

and here it is on my server:
http://www.beyondthree.com/_dev/pgraphics_bitmap_works/

+ m