Sky generation

[kaffiene]

You might also want to use a Background node for this, I know endolf has an example....

Kev

Do you know where that example might be?  Ive searched the site and Google to no avail

[kaffiene]

I can see that it uses a background node.  But reading that code and the Background.java code in Xith3D I can't see any indication that its disabling the depth test before writing the background geometry.

[endolf]

Hi
 Sorry about the delay in responding.

Ok, Java3d does disable the z buffer and draw a one unit background (in my case a sphere), xith doesn't (yet?), so you have to draw a huge cube to do it. The way I have done it for darkvoid is to create an ac3d model with the starfield texture applied that is 280 metres across (not big enough for propper play, but ok for now, corners at -140,-140,-140 to 140,140,140). This then has the texture applied to the inside of it. I use my ac3d loader to load it into xith and place it in the background. I hope that helps a little, but it's just summing up what others have said.

I'd like to see the z disabled for background nodes and a one unit size like java3d did, maybe when I've sorted a few things out here I'll look into it if no-one gets there first

Cheers

Endolf

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[Herkules]

But reading that code and the Background.java code in Xith3D I can't see any indication that its disabling the depth test before writing the background geometry.

Isn't that what I asked before?

It seems that background stuff is rendered first. So theres hope that a skybox e.g. isn't fogged away. But it still has to be a large box taking the Z-clipping into account when setting up the geometry?

[dsellars]

Sorry to bring up this old thread but I was wondering if anyone had looked into this anymore/worked out how to get it working?

It's just that it fits into something I'm thinking about at the moment, a kinda space simulation with a starfield in the background similar by the sound of it to the effect endolf wanted to create.

Cheers,
Dan.

[z.e.r.o]

I did, and noticed a strange thing.
First of all, the thing that almost every 3D tutorial seem to be forgotting about skyboxes is that you have to disable the depth buffer when drawing them around the camera, to ensure that the scene will be drawn on top of the skybox instead of partially (of totally) behind the sky geometry.

This is the rather ugly code for a skybox proto-demo. It is working correctly only if you use vertex colouring for the skybox. If you enable the texture it seems to make ignore the DepthBufferEnabled flag.
I'm doing something wrong, I hope.

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import javax.vecmath.*; import java.awt.*; import java.awt.event.*; // Xith3D import com.xith3d.scenegraph.*; import com.xith3d.test.*; import com.xith3d.loaders.texture.*; // use Jogl import com.xith3d.render.*; import com.xith3d.render.jogl.*; public class SkyBox implements KeyListener {     TransformGroup sbTG, cubeTG;     Transform3D sbT, cubeT, v;     Shape3D cube;     Shape3D box;     Vector3f eyeLoc = new Vector3f(0, 0, 10);     View view;     float angle;     float speed = 0.02f;     boolean db;         public static void main (String args[]) {         new SkyBox();     }         public SkyBox() {         db = false;                 // create the virtual universe        VirtualUniverse universe = new VirtualUniverse();                 // add a view to the universe        view = new View();         universe.addView(view);                 // add a locale        Locale locale = new Locale();         universe.addLocale(locale);                 // create a BranchGroup        BranchGroup scene = new BranchGroup();         locale.addBranchGraph(scene);                 //loads texture for the skybox        Texture2D skyTex;         TextureLoader tl = new TextureLoader();         tl.registerPath(".");         skyTex = (Texture2D)tl.getMinMapTexture("sky.png");                 sbTG = new TransformGroup();         cubeTG = new TransformGroup();         scene.addChild(sbTG);         scene.addChild(cubeTG);                 //Cube geometry        Geometry g1 = Cube.createCubeViaTriangles(0, 0, 0, 1, true);         cube = new Shape3D(g1, new Appearance());                 //Skybox geometry                 //sets renderingattributes to not use depthbuffer for the skybox        RenderingAttributes ra = new RenderingAttributes();         ra.setDepthBufferEnable(false);         Appearance boxApp = new Appearance();         boxApp.setRenderingAttributes(ra);                         //Enable this to have a blue working skybox        boxApp.setColoringAttributes(             new ColoringAttributes(             new Color3f(0.0f, 0.0f, 1.0f), ColoringAttributes.NICEST));                 //using this call broke the setRenderingAttributes!        //boxApp.setTexture(skyTex);                 Geometry g2 = Cube.createCubeViaTriangles(0, 0, 0, 10, false);         box = new Shape3D(g2, boxApp);                 sbTG.addChild(box);         cubeTG.addChild(cube);         sbT = new Transform3D();         cubeT = new Transform3D();         v = new Transform3D();         v.setTranslation(eyeLoc);         sbT.setTranslation(eyeLoc);         sbTG.setTransform(sbT);                 //ensure the cube to be OVER the Skybox to illustrate        //the disabling of the depth buffer for the skybox rendering        cubeT.setTranslation(new Vector3f(0f, 0f, -12f));         cubeTG.setTransform(cubeT);                 //Window creation lingo.        RenderPeer rp = new RenderPeerImpl();         CanvasPeer cp = rp.makeCanvas(null, 640, 480, 32, false);         Canvas3D canvas = new Canvas3D();         canvas.set3DPeer(cp);         Toolkit.getDefaultToolkit().addAWTEventListener(             new EventListener(),   AWTEvent.KEY_EVENT_MASK);                 //Place camera        view.addCanvas3D(canvas);         view.getTransform().lookAt(eyeLoc,   // location of eye            new Vector3f( 0, 0, 0),   // center of view            new Vector3f( 0, 1, 0));  // vector pointing up                 while(true) {             view.renderOnce();         }     }         public void keyPressed(KeyEvent e) {         if (e.getKeyCode() == e.VK_LEFT) {             angle = (angle + speed) % 360;             v.setTranslation(new Vector3f (0, 0, 0));             v.rotY(angle);             v.setTranslation(eyeLoc);             view.setTransform(v);             sbT.setTranslation(eyeLoc);             sbTG.setTransform(sbT);         }                 if (e.getKeyCode() == e.VK_RIGHT) {             angle = (angle - speed) % 360;             v.setTranslation(new Vector3f (0, 0, 0));             v.rotY(angle);             v.setTranslation(eyeLoc);             view.setTransform(v);             sbT.setTranslation(eyeLoc);             sbTG.setTransform(sbT);         }             }         public void keyTyped(KeyEvent e) {             }         public void keyReleased(KeyEvent e) {             }         class EventListener implements AWTEventListener {         public void eventDispatched(AWTEvent event) {             if(event instanceof KeyEvent) {                 KeyEvent e = (KeyEvent) event;                 switch(e.getID()) {                     case KeyEvent.KEY_TYPED: keyTyped(e); break;                     case KeyEvent.KEY_PRESSED: keyPressed(e); break;                     case KeyEvent.KEY_RELEASED: keyReleased(e); break;                 }             }         }     } }

Comments?

[cascade]

Hi,

don't know if this has been mentioned in this thread so far:

Terragen is a nice tool to create images for backgrounds and skyboxes.

You can find it here: www.planetside.co.uk

Besides it's a very nice tool to play with (even for beginners). See www.terradreams.de for examples from skilled terragen users.

Somewhere on the terragen site is a skybox tutorial including a script. This tutorial tells you how to create 6 images for your cube.

[z.e.r.o]

That's nice, if only Xith3D will retain depth buffer settings on the cube once textured

I also noticed that if the cube is set too large (around 50000 seem to broke in my machine) the texture binded to the cube will not show up at all.

[William Denniss]

wow!  Terragen has come a LONG way since I last used at it four years ago.  Thanks for prompting me to check it out again.

Will.

[William Denniss]

Somewhere on the terragen site is a skybox tutorial including a script. This tutorial tells you how to create 6 images for your cube.

found some:
http://www.delphigl.de/tutorials/skybox.html
http://www.blitzcoder.com/cgi-bin/articles/show_article.pl?f=gamejoseph03212002.html
http://www.blitzbasic.com/Community/posts.php?topic=25359

First one looks good.

Will.

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[William Denniss]

I can see that it uses a background node.  But reading that code and the Background.java code in Xith3D I can't see any indication that its disabling the depth test before writing the background geometry.

It isn't currently, you are correct.

I am now working to implementing this feature.

Will.

[William Denniss]

Geometry with the Background node now works properly.

Note - it you must manually tell the geom to disable the depth buffer when drawn (i.e. so that everything is drawn in front).  Do this by setting a RenderingAttribute of the geometry Appearance:

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Appearance a = new Appearance(); a.setRenderingAttributes(new RenderingAttributes()); a.getRenderingAttributes().setDepthBufferWriteEnable(false);

For a complete example, look at the Xith3DBackgroundGeomTest.

Will.