Realtime raytracing experiments in pure Java

[Varkas]

Good work!

Thanks Good to know that it runs with OpenJDK too.

I meanwhile found out why the volatile integer worked. The workerDone callback is synchronized altogether.

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public synchronized void workerDone()     {         int count = doneCount.incrementAndGet();                 if(count == workers.size())         {             notify();         }     }

Instead of doneCount.incrementAndGet() the r4 had a doneCount++ there. But since the whole method is synchronized, there was no race condition there, and it was sufficient to have the variable volatile, to make sure all cores have the same value.

Learned something again. I must say in all the years of using Java I didn't learn as much about concurrency than in this small project. It's been good to try

[gouessej]

OpenJDK 1.7 update 6

I guess my graphics tricks don't like that. Can you run it from a console window, and see if there is a ClassCastException or ArrayIndexOutOfBounds exception thrown? I had to reach deep into the raster classes to get Java2D working as a framebuffer for me.

The latest version (-r4) works, I get 11 FPS on my Intel Inside Pentium D. When I maximize the window, it becomes really slow.

[ra4king]

@ra4king: Wow, that is some gaming equipment you have there! Raytracing is a simple concept, but vector math ... well you know how to use OpenGL, so I assume have already learned most it

I am an expert in vector math and linear algebra in general. My only problem is laziness haha

Games published by our own members! Check 'em out!

[Varkas]

I've added shadows. The impact on performance seems to be about 30%, that is harsh, but it still works quite fine and the shadows add a lot to the impression.



The latest demo with shadows added:

http://www.java-gaming.org/user-generated-content/members/132627/simpleray-r6.jar

[Danny02]

would you mind puttin up your  code?
want to try if i would run well on the GPU(your code)

[Varkas]

I haven't made up my mind yet if I want to publish this as open source.

[Danny02]

why not?

[ra4king]

Doooo ittttt......I want to learn how in the world you do stuff like this :S

[Geemili]

I get 5 FPS... My computer certainly isn't the most powerful thing out there, that's for sure.

[deepthought]

this is encouraging. i'm gonna try my own idea for realtime raytracing.

Games published by our own members! Check 'em out!

[Longor1996]

Just a Question: How does your topmost code look like?
I mean the Code that is shooting the rays and puts the rgb-values into the picture.
And what do you use to display the image?

I'm just curious.

- Longor1996

[Varkas]

I'm writing the data to a BufferedImage and draw that through a g.drawImage() call. It's surprisingly fast, because I can use images without alpha channel.

The code looks like this - the real tracing code is in the object.hit() and object.trace() methods. I've tried to keep the framework expandable to have more object types but planes and spheres. TracerDataSet is kept in one instance per thread. linepix is an int [] which will take the pixels of one line. Ray, p, lineV and the like are instances of a 3D vector type. Look is the looking vector of the viewer into the scene.

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void calculateScene(int yStart, int yEnd, TracerDataSet data)     {         int width = data.linepix.length;         int height = displayPanel.getHeight();                 final int hw = width >> 1;         final int hh = height >> 1;                 for(int y=yEnd; y>yStart; y--)         {             data.lineV.set(look);             data.lineV.add(vert, y);                         for(int x=-hw; x<hw; x++)             {                 data.ray.set(data.lineV);                 data.ray.add(horz, x);                                 data.p.set(camera);                                 final int rgb = traceObjects(data);                 data.linepix[hw+x] = rgb;             }                       displayPanel.setline(hh-y, data.linepix);         }                     }         private int traceObjects(TracerDataSet data)     {         boolean go;         int brightness = 255;                 long objectRgb = -1;                 do         {             go = false;                         final double t = findIntersection(data);             if(data.bestObject != null)             {                 final long color = data.bestObject.hit(data.p, data.ray, light, t);                                 if(color == -1L)                 {                     // mirror, p and v are set up by hit().                     go = true;                     brightness = brightness * 230 >> 8;                 }                 else                 {                     objectRgb = color;                 }             }         }         while(go && brightness > 16);         if(objectRgb == -1)         {             // Nothing hit             data.ray.norm();             final int tx = (int)(Textures.clouds.getWidth() * (data.ray.x+1.0) * 0.5);             final int ty = (int)(Textures.clouds.getHeight() * (data.ray.y+1.0) * 0.5);             objectRgb = RGB.spread(Textures.clouds.getRGB(tx, ty));         }         else         {             // shadows             // need to calculate ray from data.p to light source                         data.ray.set(light);             data.ray.sub(data.p);                         findIntersection(data);             if(data.bestObject != null)             {                 // shadow                 // brightness = brightness * 10 >> 8;                 brightness = 32;             }         }                 return RGB.shadeAndCompact(objectRgb, brightness);     }     private double findIntersection(TracerDataSet data)     {         final double raylen2 = data.ray.length2();         double bestT = Double.MAX_VALUE;         data.bestObject = null;                 for(int i=0; i<objects.size(); i++)         {             final SceneObject object = objects.get(i);             final double t = object.trace(data.p, data.ray, raylen2);             if(t >= 0 && t < bestT)             {                 data.bestObject = object;                 bestT = t;             }         }                 return bestT;     }

[Varkas]

would you mind puttin up your  code?
want to try if i would run well on the GPU(your code)

I'll clean up the code a bit and publish it under the GPL as part of this project:

http://sourceforge.net/p/freemapper/code/26/tree/gardenlife/trunk/

Give me some hours ...

Edit:

The code is there now. It's a bit farther evolved than the one used for the demo in this thread, but it didn't cut into performance too badly. The SimpleRay class has a main method which you can run and which will show the demo scene:

http://sourceforge.net/p/freemapper/code/27/tree/gardenlife/trunk/src/tracer/

I want to use the tracer for this project eventually:

http://www.java-gaming.org/topics/greenspace-a-park-or-landscape-design-toy/27520/msg/258381/view.html#msg258381

[krasse]

Nice!
I get a quite steady 40fps with shadows, which is really impressive

[Varkas]

People can now begin to stop saying "Java is slow"

I'm also positively impressed. I didn't expect this when I started, although I knew that the Java runtime got much better during the past years.

[Sammyster]

That was really cool.

40-45fps with the shadows, not bad