Strange transform behavior

Hi all,



playing with the TestEnvMap test I tried to add a cylinder to the scene but I'm facing a strange behavior when slowly moving the scene with mouse or keys. It seems the cylinder "sticks" to a certain position (perpendicular to the viewpoint). Is this a bug ?



here's the source (1:1 the same in SVN, except the cylinder)



Cheers,



Mik



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package jmetest.renderer;

import com.jme.app.SimpleGame;
import com.jme.image.Texture;
import com.jme.input.NodeHandler;
import com.jme.light.PointLight;
import com.jme.math.Quaternion;
import com.jme.math.Vector3f;
import com.jme.renderer.ColorRGBA;
import com.jme.renderer.Renderer;
import com.jme.scene.shape.Cylinder;
import com.jme.scene.shape.Quad;
import com.jme.scene.shape.Torus;
import com.jme.scene.state.BlendState;
import com.jme.scene.state.TextureState;
import com.jme.scene.state.BlendState.DestinationFunction;
import com.jme.scene.state.BlendState.SourceFunction;
import com.jme.util.TextureManager;

/**
 * <code>TestEnvMap</code>
 *
 * @author Mark Powell
 * @version $Id: TestEnvMap.java 4130 2009-03-19 20:04:51Z blaine.dev $
 */
public class TestEnvMap extends SimpleGame
{

   public static void main(String[] args)
   {
      TestEnvMap app = new TestEnvMap();
      app.setConfigShowMode(ConfigShowMode.AlwaysShow);
      app.start();
   }

   protected void simpleInitGame()
   {
      display.setTitle("Environmental Maps");

      cam.setLocation(new Vector3f(0, 0, 100));
      cam.update();

      Torus torus = new Torus("Torus", 50, 50, 10, 20);

      Quad background = new Quad("Background");
      background.updateGeometry(150, 120);
      background.setLocalTranslation(new Vector3f(0, 0, -30));

      Texture bg = TextureManager.loadTexture(TestEnvMap.class.getClassLoader().getResource("jmetest/data/texture/clouds.png"), Texture.MinificationFilter.BilinearNearestMipMap, Texture.MagnificationFilter.Bilinear);
      TextureState bgts = display.getRenderer().createTextureState();
      bgts.setTexture(bg);
      bgts.setEnabled(true);
      background.setRenderState(bgts);

      TextureState ts = display.getRenderer().createTextureState();
      // Base texture, not environmental map.
      Texture t0 = TextureManager.loadTexture(TestEnvMap.class.getClassLoader().getResource("jmetest/data/images/Monkey.jpg"), Texture.MinificationFilter.Trilinear, Texture.MagnificationFilter.Bilinear);
      // Environmental Map (reflection of clouds)
      Texture t = TextureManager.loadTexture(TestEnvMap.class.getClassLoader().getResource("jmetest/data/texture/clouds.png"), Texture.MinificationFilter.Trilinear, Texture.MagnificationFilter.Bilinear);
      t.setEnvironmentalMapMode(Texture.EnvironmentalMapMode.SphereMap);
      ts.setTexture(t0, 0);
      ts.setTexture(t, 1);
      ts.setEnabled(true);

      PointLight pl = new PointLight();
      pl.setAmbient(new ColorRGBA(0.75f, 0.75f, 0.75f, 1));
      pl.setDiffuse(new ColorRGBA(1, 0, 0, 1));
      pl.setLocation(new Vector3f(50, 0, 0));
      pl.setEnabled(true);

      lightState.attach(pl);

      // MIK   test   
      BlendState bs = display.getRenderer().createBlendState();
      bs.setBlendEnabled(true);
      bs.setSourceFunction(SourceFunction.SourceAlpha);
      bs.setDestinationFunction(DestinationFunction.DestinationAlpha);
      torus.setRenderState(bs);
      torus.setRenderQueueMode(Renderer.QUEUE_TRANSPARENT);
      
      Cylinder c = new Cylinder("Cylinder", 10, 10, 10, 120);
      //c.setRenderState(bs);
      //c.setRenderState(ts);
      c.setLocalRotation(new Quaternion(.1f,0,0,1));
      
      c.setRenderQueueMode(Renderer.QUEUE_TRANSPARENT);
      rootNode.attachChild(c);
      //////

      torus.setRenderState(ts);
      rootNode.attachChild(torus);
      rootNode.attachChild(background);

      input = new NodeHandler(rootNode, 10, 2);
      //input = new NodeHandler(torus, 10, 2);
   }
}

Little follow-up: the strange behavior happens from the second time I start the sample. Really strange. A must see…



Mik

i cant notice anything strange, the whole scene moves correctly.

I've cutted the torus, background, then recorded and upped a video that explains the error I see.



here: http://www.classx.it/public/tmp/transform_err.avi  (XVID)






To me it looks similar to gimbal lock. Could just be the way the rotations are implemented in the KeyNodeRotate* actions using a rotation matrix.

I changed it to simple quaternion multiplication and it still happens.

But only with the cylinder, not with any other primitve.


If you remove the line -


c.setLocalRotation(new Quaternion(.1f,0,0,1));



the glitch disappears, but I have absolutely no idea why.  Actually, if you increase the .1f to something else, the problem gets even worse which at least makes it easier to see.
The problem exists for all primitive types I have tried (with the .1 above set to .9 to make it more noticable), and added this to show the problem without relying on mouse control -

float angle=0;
public void simpleUpdate(){
rootNode.getLocalRotation().fromAngleAxis(angle*FastMath.DEG_TO_RAD, Vector3f.UNIT_Y);
angle+=.1;
}


Then tried with various primitive types replacing the cylinder :-
    Capsule c = new Capsule("Cylinder", 10, 3, 10, 10, 120);
    Box c = new Box("Cylinder", new Vector3f(0,0,0), 10, 10, 10);
    Box c = new Box("Cylinder", new Vector3f(0,0,0), 10, 10, 60);


Basically - get rid of the line :D
I have no idea what the problem is, just hope my findings help someone else point it out.

I only do binary - this maths stuff makes my head hurt  :D

i didn't even notice the line :slight_smile: