It is android version. I got it from first post in this topic.

Nice classes, but I wonder. Did somebody use GLFont.getStringBounds(String s)? May be I downloaded older version of this class. But there is simple error. This method GLFont.getStringBounds(String s) doesn't work, it always returns width = 0.  This is happening because of charWidths[] array isn't filled on setting Paint.
Just pointing on this simple copy/paste error 

Good user friendly decision). Thanks.

Thanks for quick answer. I spent some more time yesterday and finally found a reason. All my tile 3d objects creating from a static sample which is loaded from 3ds file in Utils class:

private static Object3D tile3D; // sample

public static Object3D getNewTile3D(Context context){
if(tile3D == null){
Object3D[] objs = Loader.load3DS(context.getResources().openRawResource(R.raw.tile_box_44faces), 2);
if(objs == null || objs.length == 0) return null;
tile3D = objs[0];
}
return tile3D.cloneObject();
}


On first start of FieldActivity sample object is loaded from file and saved in static field. But on second start sample is already unusable and causes such exception. I really don't now why.
So what is a proper way to do such things?

"close and open it again" means that I press BACK button when on FieldActivity and MainActivity becomes visible( instance of FiledActivity still can be in Activity steck), and then I send just the same  intent to start FieldActivity like in first start:

Intent i = new Intent(MainAct.this,FieldAct.class);
MainAct.this.startActivity(i);

Full log:

01-17 06:57:42.272: INFO/ActivityManager(56): Starting activity: Intent { cmp=com.codand.mahjong3d/.FieldAct (has extras) }
01-17 06:57:42.732: DEBUG/dalvikvm(226): GC freed 5997 objects / 378000 bytes in 79ms
01-17 06:57:42.772: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:42.852: DEBUG/dalvikvm(226): GC freed 381 objects / 16128 bytes in 77ms
01-17 06:57:42.862: INFO/dalvikvm-heap(226): Grow heap (frag case) to 4.647MB for 262160-byte allocation
01-17 06:57:42.942: DEBUG/dalvikvm(226): GC freed 4 objects / 136 bytes in 83ms
01-17 06:57:42.992: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.022: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.042: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.142: DEBUG/dalvikvm(226): GC freed 41 objects / 1784 bytes in 68ms
01-17 06:57:43.222: DEBUG/dalvikvm(226): GC freed 28 objects / 1120 bytes in 78ms
01-17 06:57:43.232: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.264: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.292: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.312: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.335: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.442: DEBUG/dalvikvm(226): GC freed 55 objects / 2536 bytes in 73ms
01-17 06:57:43.522: DEBUG/dalvikvm(226): GC freed 42 objects / 1800 bytes in 72ms
01-17 06:57:43.542: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.562: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.582: INFO/jPCT-AE(226): Loading Texture...
01-17 06:57:43.942: DEBUG/dalvikvm(226): GC freed 14819 objects / 505928 bytes in 81ms
01-17 06:57:44.322: DEBUG/dalvikvm(226): GC freed 16729 objects / 571784 bytes in 83ms
01-17 06:57:44.692: DEBUG/dalvikvm(226): GC freed 15323 objects / 523976 bytes in 87ms
01-17 06:57:45.042: DEBUG/dalvikvm(226): GC freed 15319 objects / 523904 bytes in 85ms
01-17 06:57:45.392: DEBUG/dalvikvm(226): GC freed 15320 objects / 523952 bytes in 82ms
01-17 06:57:45.772: DEBUG/dalvikvm(226): GC freed 15282 objects / 523800 bytes in 82ms
01-17 06:57:46.152: DEBUG/dalvikvm(226): GC freed 15284 objects / 523880 bytes in 82ms
01-17 06:57:46.552: DEBUG/dalvikvm(226): GC freed 15242 objects / 523656 bytes in 82ms
01-17 06:57:46.942: DEBUG/dalvikvm(226): GC freed 15240 objects / 523632 bytes in 83ms
01-17 06:57:47.413: DEBUG/dalvikvm(226): GC freed 15206 objects / 523424 bytes in 149ms
01-17 06:57:47.892: DEBUG/dalvikvm(226): GC freed 15134 objects / 522896 bytes in 90ms
01-17 06:57:48.092: DEBUG/libEGL(226): egl.cfg not found, using default config
01-17 06:57:48.102: DEBUG/libEGL(226): loaded /system/lib/egl/libGLES_android.so
01-17 06:57:48.152: INFO/jPCT-AE(226): OpenGL vendor:     Android
01-17 06:57:48.152: INFO/jPCT-AE(226): OpenGL renderer:   Android PixelFlinger 1.2
01-17 06:57:48.182: INFO/jPCT-AE(226): OpenGL version:    OpenGL ES-CM 1.0
01-17 06:57:48.182: INFO/jPCT-AE(226): OpenGL renderer initialized (using 2 texture stages)
01-17 06:57:48.223: INFO/jPCT-AE(226): Loading file from InputStream
01-17 06:57:48.223: INFO/jPCT-AE(226): File from InputStream loaded...2763 bytes
01-17 06:57:48.242: INFO/jPCT-AE(226): Processing new material 01 - Default!
01-17 06:57:48.242: INFO/jPCT-AE(226): Texture named GIFT.PNG added to TextureManager!
01-17 06:57:48.242: INFO/jPCT-AE(226): Processing object from 3DS-file: Tile
01-17 06:57:48.262: INFO/jPCT-AE(226): Object 'Tile_jPCT1' created using 44 polygons and 24 vertices.
01-17 06:57:48.562: DEBUG/dalvikvm(226): GC freed 6214 objects / 366104 bytes in 86ms
01-17 06:57:48.863: INFO/jPCT-AE(226): Adding Lightsource: 0
01-17 06:57:48.863: INFO/jPCT-AE(226): Memory usage before compacting: 3700 KB used out of 4295 KB
01-17 06:57:48.963: DEBUG/dalvikvm(226): GC freed 4503 objects / 324296 bytes in 90ms
01-17 06:57:49.043: DEBUG/dalvikvm(226): GC freed 73 objects / 2312 bytes in 81ms
01-17 06:57:49.207: INFO/jPCT-AE(226): Memory usage after compacting: 3382 KB used out of 4295 KB
01-17 06:57:49.233: INFO/jPCT-AE(226): Subobject of object 2/object4 compiled to flat fixed point data using 132 vertices in 4ms!
01-17 06:57:49.243: INFO/jPCT-AE(226): Object 2/object4 compiled to 1 subobjects in 21ms!
01-17 06:57:49.243: INFO/jPCT-AE(226): Object 'object4' uses one texture set!
01-17 06:57:49.253: INFO/jPCT-AE(226): Object 3/object5 precompiled!
01-17 06:57:49.253: INFO/jPCT-AE(226): Object 'object5' uses one texture set!
01-17 06:57:49.253: INFO/jPCT-AE(226): Object 4/object6 precompiled!
01-17 06:57:49.263: INFO/jPCT-AE(226): Object 'object6' uses one texture set!
01-17 06:57:49.263: INFO/jPCT-AE(226): Object 5/object7 precompiled!
01-17 06:57:49.273: INFO/jPCT-AE(226): Object 'object7' uses one texture set!
01-17 06:57:49.273: INFO/jPCT-AE(226): Object 6/object8 precompiled!
01-17 06:57:49.273: INFO/jPCT-AE(226): Object 'object8' uses one texture set!
01-17 06:57:49.273: INFO/jPCT-AE(226): Object 7/object9 precompiled!
...lines lines lines...
01-17 06:57:49.653: INFO/jPCT-AE(226): Object 59/object61 precompiled!
01-17 06:57:49.653: INFO/jPCT-AE(226): Object 'object61' uses one texture set!
01-17 06:57:49.663: INFO/jPCT-AE(226): Object 60/object62 precompiled!
01-17 06:57:49.663: INFO/jPCT-AE(226): Object 'object62' uses one texture set!
01-17 06:57:49.674: INFO/jPCT-AE(226): Object 61/object63 precompiled!
01-17 06:57:49.674: INFO/jPCT-AE(226): Object 'object63' uses one texture set!
01-17 06:57:49.674: INFO/jPCT-AE(226): [ 1295247469679 ] - WARNING: Object object2 hasn't been build yet. Forcing build()!
01-17 06:57:49.685: INFO/jPCT-AE(226): Subobject of object 62/object64 compiled to flat fixed point data using 6 vertices in 9ms!
01-17 06:57:49.693: INFO/jPCT-AE(226): Object 62/object64 compiled to 1 subobjects in 14ms!
01-17 06:57:49.813: DEBUG/dalvikvm(226): GC freed 1924 objects / 172104 bytes in 106ms
01-17 06:57:50.253: INFO/ARMAssembler(226): generated scanline__000000B7:03010144_00009501_00000000 [126 ipp] (207 ins) at [0x2d5478:0x2d57b4] in 6201067 ns
01-17 06:57:50.323: INFO/jPCT-AE(226): Object 'object39' shares compiled data with object 'object4'
01-17 06:57:50.333: INFO/jPCT-AE(226): Object 'object6' shares compiled data with object 'object4'
01-17 06:57:50.373: INFO/jPCT-AE(226): Object 'object35' shares compiled data with object 'object4'
01-17 06:57:50.373: INFO/jPCT-AE(226): Object 'object31' shares compiled data with object 'object4'
01-17 06:57:50.383: INFO/jPCT-AE(226): Object 'object42' shares compiled data with object 'object4'
01-17 06:57:50.395: INFO/jPCT-AE(226): Object 'object16' shares compiled data with object 'object4'
01-17 06:57:50.413: INFO/jPCT-AE(226): Object 'object58' shares compiled data with object 'object4'
01-17 06:57:50.434: INFO/jPCT-AE(226): Object 'object12' shares compiled data with object 'object4'
01-17 06:57:50.434: INFO/jPCT-AE(226): Object 'object62' shares compiled data with object 'object4'
...lines lines lines...
01-17 06:57:50.883: INFO/jPCT-AE(226): Object 'object29' shares compiled data with object 'object4'
01-17 06:57:50.893: INFO/jPCT-AE(226): Object 'object27' shares compiled data with object 'object4'
01-17 06:57:50.893: INFO/jPCT-AE(226): Object 'object23' shares compiled data with object 'object4'
01-17 06:57:50.904: INFO/jPCT-AE(226): Object 'object51' shares compiled data with object 'object4'
01-17 06:57:50.913: INFO/jPCT-AE(226): Object 'object18' shares compiled data with object 'object4'
01-17 06:57:50.923: INFO/jPCT-AE(226): 0 fps
01-17 06:57:51.163: INFO/ActivityManager(56): Displayed activity com.codand.mahjong3d/.FieldAct: 8855 ms (total 8855 ms)
01-17 06:57:52.093: INFO/jPCT-AE(226): 5 fps
01-17 06:57:53.103: INFO/jPCT-AE(226): 5 fps
01-17 06:57:54.133: INFO/jPCT-AE(226): 5 fps
01-17 06:57:55.273: INFO/jPCT-AE(226): 5 fps
01-17 06:57:56.293: INFO/jPCT-AE(226): 5 fps
01-17 06:57:57.303: INFO/jPCT-AE(226): 5 fps
01-17 06:57:58.362: INFO/jPCT-AE(226): 4 fps
... press BACK button...
01-17 06:58:20.932: WARN/KeyCharacterMap(226): No keyboard for id 0
01-17 06:58:20.942: WARN/KeyCharacterMap(226): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
... start FilendActivity again...
01-17 07:02:02.562: INFO/ActivityManager(56): Starting activity: Intent { cmp=com.codand.mahjong3d/.FieldAct (has extras) }
01-17 07:02:07.062: INFO/jPCT-AE(226): OpenGL vendor:     Android
01-17 07:02:07.062: INFO/jPCT-AE(226): OpenGL renderer:   Android PixelFlinger 1.2
01-17 07:02:07.072: INFO/jPCT-AE(226): OpenGL version:    OpenGL ES-CM 1.0
01-17 07:02:07.072: INFO/jPCT-AE(226): OpenGL renderer initialized (using 2 texture stages)
01-17 07:02:07.492: DEBUG/dalvikvm(226): GC freed 6283 objects / 468952 bytes in 93ms
01-17 07:02:07.502: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.502: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.512: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.522: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.522: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.532: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.542: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.542: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.552: INFO/jPCT-AE(226): 44 polygons in tile
01-17 07:02:07.593: INFO/jPCT-AE(226): Adding Lightsource: 0
01-17 07:02:07.612: INFO/jPCT-AE(226): Memory usage before compacting: 3862 KB used out of 4743 KB
01-17 07:02:07.802: DEBUG/dalvikvm(226): GC freed 1636 objects / 104264 bytes in 179ms
01-17 07:02:07.892: DEBUG/dalvikvm(226): GC freed 72 objects / 2288 bytes in 90ms
01-17 07:02:08.052: INFO/jPCT-AE(226): Memory usage after compacting: 3759 KB used out of 4743 KB
01-17 07:02:08.072: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.072: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.072: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.172: INFO/jPCT-AE(226): Additional visibility list (2) created with size: 512
01-17 07:02:08.212: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.212: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.212: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.252: INFO/jPCT-AE(226): Additional visibility list (3) created with size: 512
01-17 07:02:08.272: INFO/ActivityManager(56): Displayed activity com.codand.mahjong3d/.FieldAct: 5691 ms (total 5691 ms)
01-17 07:02:08.292: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.292: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.292: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.302: INFO/jPCT-AE(226): Additional visibility list (4) created with size: 512
01-17 07:02:08.312: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.312: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.312: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.333: INFO/jPCT-AE(226): Additional visibility list (5) created with size: 512
01-17 07:02:08.342: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.342: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.342: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.362: INFO/jPCT-AE(226): Additional visibility list (6) created with size: 512
01-17 07:02:08.372: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.372: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.372: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.382: INFO/jPCT-AE(226): Additional visibility list (7) created with size: 512
01-17 07:02:08.402: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.402: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.402: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.412: INFO/jPCT-AE(226): Additional visibility list (8) created with size: 512
01-17 07:02:08.432: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.432: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.432: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.442: INFO/jPCT-AE(226): Additional visibility list (9) created with size: 512
01-17 07:02:08.462: INFO/jPCT-AE(226): java.lang.NullPointerException
01-17 07:02:08.462: INFO/jPCT-AE(226):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at com.threed.jpct.World.compile(World.java:2029)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at com.threed.jpct.World.renderScene(World.java:1060)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-17 07:02:08.462: INFO/jPCT-AE(226):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-17 07:02:08.482: INFO/jPCT-AE(226): Additional visibility list (10) created with size: 512


Ad about version of engine) May be it is a stupid question but where can I see version ?)
Any way thanks for reply.

I am developing small game on android, some kind of 3d mahjong. Currently it has two Activities:
1) MainActivity -  starting activity with list of available maps.
2) FieldActivity - playground activity with GlSurfaceView where all show begins.
When FieldActivity starts first all goes great. But when I close it and then open it again (by selecting other map) in log appears exception(on each call World.renderScene()) and display goes black:

01-16 19:53:03.645: INFO/jPCT-AE(2004): java.lang.NullPointerException
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at com.threed.jpct.World.compile(World.java:2029)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at com.threed.jpct.World.renderScene(World.java:1060)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-16 19:53:03.645: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-16 19:53:03.655: INFO/jPCT-AE(2004): Additional visibility list (32) created with size: 512
01-16 19:53:03.675: INFO/jPCT-AE(2004): java.lang.NullPointerException
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at com.threed.jpct.World.compile(World.java:2029)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at com.threed.jpct.World.renderScene(World.java:1060)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-16 19:53:03.675: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-16 19:53:03.685: INFO/jPCT-AE(2004): Additional visibility list (33) created with size: 512
01-16 19:53:03.705: INFO/jPCT-AE(2004): java.lang.NullPointerException
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at com.threed.jpct.CompiledInstance.fill(CompiledInstance.java:823)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at com.threed.jpct.Object3DCompiler.compile(Object3DCompiler.java:134)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at com.threed.jpct.World.compile(World.java:2029)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at com.threed.jpct.World.renderScene(World.java:1060)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at com.codand.mahjong3d.renderer.PlaygroundRenderer.onDrawFrame(PlaygroundRenderer.java:113)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1127)
01-16 19:53:03.705: INFO/jPCT-AE(2004):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:975)
01-16 19:53:03.714: INFO/jPCT-AE(2004): Additional visibility list (34) created with size: 512

This is source code of FiledActivity

package com.codand.mahjong3d.renderer;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import com.codand.mahjong3d.entity.Model;
import com.codand.mahjong3d.entity.Tile;
import com.codand.mahjong3d.utils.Utils;
import com.threed.jpct.Camera;
import com.threed.jpct.FrameBuffer;
import com.threed.jpct.Interact2D;
import com.threed.jpct.Light;
import com.threed.jpct.Logger;
import com.threed.jpct.Matrix;
import com.threed.jpct.Object3D;
import com.threed.jpct.RGBColor;
import com.threed.jpct.SimpleVector;
import com.threed.jpct.Texture;
import com.threed.jpct.TextureManager;
import com.threed.jpct.World;
import com.threed.jpct.util.MemoryHelper;

import android.content.Context;
import android.opengl.GLSurfaceView;

public class PlaygroundRenderer implements GLSurfaceView.Renderer,Model.ModelListener{

private static final float TILE_SCALE = (float)10.1;
private static final float TILE_MARGIN = (float)0.0;

private static final int TILE_ICON_SIZE = 60;
private static final int TILE_ICON_X = 10;
private static final int TILE_ICON_Y = 10;

private static final float MIN_CAMERA_MOVE = 150;
private static final float CAMERA_MOVE_STEP = 2;
private static final float BORDER_SIZE = 40;

private static final float SUN_DISTANCE = 1000;

private static final int START_TRANSPARENCY = 4;
private static final int TRANSPARENCY_DECREASE = 3;

private Context context;

private Model model;

private Object3D model3D;
private ArrayList<Object3D> tiles3D;
private HashMap<String,Object3D> tileMap = new HashMap<String,Object3D>();
private float[] boundingBox;
private boolean calcBoundingBox = false;

private Object3D skyPlane;

private long time = System.currentTimeMillis();
private long lastFrameTime;
private float period = 0; // time after last frame in sec


private World world;
private Light sun;
private FrameBuffer fb;
private ArrayList<Object3D> removingObjects = new ArrayList<Object3D>();

private boolean stop;
private boolean isWorldInited = false;

private RGBColor back = new RGBColor(0, 0, 0);
private RGBColor selectionColor = new RGBColor(0,500,0);

private float xImpulse = 0;
private float yImpulse = 0;
private float resist   = (float)0.02;

private int fps = 0;

public PlaygroundRenderer(Context context,Model model) {
super();
this.context = context;
this.model = model;
this.model.addListener(this);
}



public Model getModel() {
return model;
}

public void stop(){
stop = true;
}

@Override
public void onDrawFrame(GL10 arg0) {
try {
if (!stop) {
//long testTime = System.currentTimeMillis();
updatePeriod();
processCameraMovement();
removeMarkedObjects();

//Logger.log((System.currentTimeMillis() - testTime) + " dirst functions");
//testTime = System.currentTimeMillis();
fb.clear(back);
//Logger.log((System.currentTimeMillis() - testTime) + " fb.clear(back)");
//testTime = System.currentTimeMillis();
world.renderScene(fb);
//Logger.log((System.currentTimeMillis() - testTime) + " world.renderScene(fb)");
//testTime = System.currentTimeMillis();
world.draw(fb);
//Logger.log((System.currentTimeMillis() - testTime) + " world.draw(fb)");
//testTime = System.currentTimeMillis();
drawSelectionBlitting();
adjustFitness();
//Logger.log((System.currentTimeMillis() - testTime) + " adjustFitness()");
//testTime = System.currentTimeMillis();
fb.display();
//Logger.log((System.currentTimeMillis() - testTime) + " fb.display()");
//testTime = System.currentTimeMillis();
if(Math.abs(xImpulse) > 2*resist){
xImpulse = xImpulse - Math.signum(xImpulse)*resist*period;
}
if (Math.abs(yImpulse) > 2*resist ) {
yImpulse = yImpulse - Math.signum(yImpulse)*resist*period;
}

if (System.currentTimeMillis() - time >= 1000) {
Logger.log(fps + " fps");
fps = 0;
time = System.currentTimeMillis();
}
fps++;
} else {
if (fb != null) {
fb.dispose();
fb = null;
}
}
} catch (Exception e) {
Logger.log(e, Logger.MESSAGE);
}

}

@Override
public void onSurfaceChanged(GL10 gl, int w, int h) {
if (fb != null) {
fb.dispose();
}
fb = new FrameBuffer(gl, w, h);

initWorld();

/*
fb = new FrameBuffer(gl, w, h);

world = new World();
world.setAmbientLight(200, 10, 10);

sun = new Light(world);
sun.setIntensity(250, 250, 250);

// Create a texture out of the icon...:-)
if(!TextureManager.getInstance().containsTexture("texture")){
Texture texture = new Texture(BitmapHelper.rescale(BitmapHelper.convert(context.getResources().getDrawable(R.drawable.test)), 64, 64));
TextureManager.getInstance().addTexture("texture", texture);
}
cube = Primitives.getCube(10);
cube.calcTextureWrapSpherical();
cube.setTexture("texture");
cube.strip();
cube.build();

world.addObject(cube);

Camera cam = world.getCamera();
cam.moveCamera(Camera.CAMERA_MOVEOUT, 50);
cam.lookAt(cube.getTransformedCenter());

SimpleVector sv = new SimpleVector();
sv.set(cube.getTransformedCenter());
sv.y -= 100;
sv.z -= 100;
sun.setPosition(sv);
MemoryHelper.compact();
*/
}

@Override
public void onSurfaceCreated(GL10 arg0, EGLConfig arg1) {
//Utils.loadTextures(context);

}

private void initWorld(){
if(model == null) return;

if(world != null){
world.removeAll();
}

world = new World();
world.setAmbientLight(200, 200, 200);

initModel();
initSky();

Camera cam = world.getCamera();

cam.setPosition(model3D.getTransformedCenter());
cam.moveCamera(Camera.CAMERA_MOVEOUT, MIN_CAMERA_MOVE);
cam.lookAt(model3D.getTransformedCenter());

sun = new Light(world);
sun.setIntensity(10, 10, 10);

SimpleVector center = model3D.getTransformedCenter();
SimpleVector dir = cam.getDirection();
dir.scalarMul(-1);
dir.add(cam.getUpVector());
SimpleVector tmp = cam.getSideVector();
tmp.scalarMul(-1);
dir.add(tmp);
dir.scalarMul(SUN_DISTANCE);
center.add(dir);
sun.setPosition(center);

MemoryHelper.compact();
isWorldInited = true;
}

private void initSky(){
skyPlane = new Object3D(2);
float offset = 1000;
skyPlane.addTriangle(new SimpleVector(-offset,-offset,0), 0, 0,
new SimpleVector(-offset,offset,0), 0, 1,
new SimpleVector(offset,offset,0), 1, 1,
TextureManager.getInstance().getTextureID(Utils.SKY_TEXTURE_NAME));

skyPlane.addTriangle(new SimpleVector(offset,offset,0), 1, 1,
new SimpleVector(offset,-offset,0), 1, 0,
new SimpleVector(-offset,-offset,0), 0, 0,
TextureManager.getInstance().getTextureID(Utils.SKY_TEXTURE_NAME));
//skyPlane.setBillboarding(Object3D.BILLBOARDING_ENABLED);
skyPlane.build();
SimpleVector center = model3D.getTransformedCenter();
center.z += 500;
skyPlane.translate(center);

world.addObject(skyPlane);
}

private void deinitModel(){
if(model3D != null){
world.removeObject(model3D);
model3D = null;
}
if(tiles3D != null){
for(int i = 0; i < tiles3D.size();i++){
world.removeObject(tiles3D.get(i));
}
tiles3D.clear();
tileMap.clear();
removingObjects.clear();
}
}

private void initModel(){
deinitModel();
model3D = Object3D.createDummyObj();

List<Tile> tiles = model.getTiles();
Object3D tile3D;
Tile tile;
tiles3D = new ArrayList<Object3D>();
tileMap.clear();
for(int i = 0;i < tiles.size();i++){
tile = tiles.get(i);
tile3D = createTile(tile);
if(i != 0){
tile3D.shareCompiledData(tiles3D.get(0));
}
//tile3D = Primitives.getCube(TILE_SCALE);
//tile3D.setUserObject(tile);
//tile3D.setCollisionMode(Object3D.COLLISION_CHECK_OTHERS);
//tile3D.rotateY((float)Math.PI/4);
//tile3D.setTransparency(10);
//tile3D.translate(getTileX(tile), getTileY(tile), getTileZ(tile));
//tile3D.calcTextureWrapSpherical();
//tile3D.setTexture(Utils.getTextureByType(tile.type));

//tile3D.strip();
//tile3D.build();
tiles3D.add(tile3D);
tileMap.put(Tile.getTileKey(tile), tile3D);
world.addObject(tile3D);

}
calculateModelBoundingBox();
model3D.translate((boundingBox[1]+boundingBox[0])/2,(boundingBox[2]+boundingBox[3])/2,(boundingBox[4]+boundingBox[5])/2);
//model3D.rotateY((float)Math.PI/4);
world.addObject(model3D);
for(int i = 0;i < tiles3D.size();i++){
model3D.addChild(tiles3D.get(i));
tiles3D.get(i).translate(-(boundingBox[1]+boundingBox[0])/2, -(boundingBox[2]+boundingBox[3])/2, -(boundingBox[4]+boundingBox[5])/2);
}
}

private Object3D createTile(Tile tile){
//Object3D[] objs;
Object3D tile3D = Utils.getNewTile3D(context);
//objs = new Object3D[1];
//tile3D = Primitives.getCube(TILE_SCALE);
//tile3D.rotateY((float)Math.PI/4);
int polygonCount = tile3D.getPolygonManager().getMaxPolygonID();
Logger.log(polygonCount + " polygons in tile");
tile3D.setUserObject(tile);
tile3D.setCollisionMode(Object3D.COLLISION_CHECK_OTHERS);
tile3D.translate(getTileX(tile), getTileY(tile), getTileZ(tile));
//tile3D.setTransparency(100);
//tile3D.calcTextureWrapSpherical();
tile3D.setTexture(Utils.getTextureByType(tile.type));

//tile3D.setTexture(Utils.getTextureInfoByType(tile.type));
tile3D.strip();
tile3D.build();

return tile3D;
}

private void updatePeriod(){
long curTime = System.currentTimeMillis();
if(lastFrameTime != 0){
period = (float)(curTime-lastFrameTime)/1000;
}
lastFrameTime = curTime;
}

private Object3D get(Tile tile){
String key = Tile.getTileKey(tile);
if(!tileMap.containsKey(key)) return null;

return tileMap.get(key);
}

private void remove(Tile tile){
Object3D tile3D = get(tile);
if(tile3D == null) return;
tile3D.setCollisionMode(Object3D.COLLISION_CHECK_NONE);
removingObjects.add(tile3D);
tiles3D.remove(tile3D);
tileMap.remove(Tile.getTileKey(tile));
}

private void select(Tile tile){
Object3D tile3D = get(tile);
if(tile3D == null) return;
tile3D.setAdditionalColor(selectionColor);
}

private void deselect(Tile tile){
Object3D tile3D = get(tile);
if(tile3D == null) return;

tile3D.clearAdditionalColor();
}

private void calculateModelBoundingBox(){
calcBoundingBox = true;
boundingBox = new float[]{Float.MAX_VALUE,Float.MIN_VALUE,
  Float.MAX_VALUE,Float.MIN_VALUE,
  Float.MAX_VALUE,Float.MIN_VALUE};
float[] bb;
Object3D tile3D;
for(int i = 0;i < tiles3D.size();i++){
tile3D = tiles3D.get(i);
bb = getBoundingBoxInWorld(tile3D);

boundingBox[0] = bb[0] < boundingBox[0] ? bb[0] : boundingBox[0];
boundingBox[1] = bb[1] > boundingBox[1] ? bb[1] : boundingBox[1];
boundingBox[2] = bb[2] < boundingBox[2] ? bb[2] : boundingBox[2];
boundingBox[3] = bb[3] > boundingBox[3] ? bb[3] : boundingBox[3];
boundingBox[4] = bb[4] < boundingBox[4] ? bb[4] : boundingBox[4];
boundingBox[5] = bb[5] > boundingBox[5] ? bb[5] : boundingBox[5];
}
calcBoundingBox = false;
}

private float[] getBoundingBoxInWorld(Object3D model){
float[] bb = model.getMesh().getBoundingBox();
float[] result = new float[]{Float.MAX_VALUE,Float.MIN_VALUE,
  Float.MAX_VALUE,Float.MIN_VALUE,
  Float.MAX_VALUE,Float.MIN_VALUE};
SimpleVector tmp;
Matrix trans = model.getWorldTransformation();
tmp = new SimpleVector(bb[0],bb[2],bb[4]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[0],bb[2],bb[5]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[0],bb[3],bb[4]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[0],bb[3],bb[5]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[1],bb[2],bb[4]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[1],bb[2],bb[5]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[1],bb[3],bb[4]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

tmp.set(bb[1],bb[3],bb[5]);
tmp.matMul(trans);
updateBoundingBox(result,tmp.x,tmp.y,tmp.z);

return result;
}

private void updateBoundingBox(float[] result, float x, float y, float z){
result[0] = x < result[0] ? x : result[0];
result[1] = x > result[1] ? x : result[1];
result[2] = y < result[2] ? y : result[2];
result[3] = y > result[3] ? y : result[3];
result[4] = z < result[4] ? z : result[4];
result[5] = z > result[5] ? z : result[5];
}

private void removeMarkedObjects(){
if(removingObjects.isEmpty()) return;
Object3D obj;
int tr;
for(int i = 0;i < removingObjects.size();i++){
obj = removingObjects.get(i);
tr = obj.getTransparency();
if(tr == -1){
obj.setTransparency(START_TRANSPARENCY);
}else{
tr = tr - TRANSPARENCY_DECREASE;
if(tr < 0){
world.removeObject(obj);
removingObjects.remove(obj);
i--;
}else{
obj.setTransparency(tr);
}
}
}
}

private void drawSelectionBlitting(){
Tile tile = model.getSelected();
if(tile == null) return;

String texName = Utils.getTextureByType(tile.type);
Texture tex = TextureManager.getInstance().getTexture(texName);
fb.blit(tex,
0, 0,
TILE_ICON_X, TILE_ICON_Y,
tex.getWidth(), tex.getHeight(),
TILE_ICON_SIZE, TILE_ICON_SIZE, -1, false, null);
}

private void adjustFitness(){
if(calcBoundingBox || isCameraRotating() || boundingBox == null || fb == null) return;
if(world == null) return;

Camera cam = world.getCamera();
float width = fb.getWidth();
float height = fb.getHeight();
boolean moveOut = false;
boolean moveIn = true;
SimpleVector tmp = new SimpleVector();
SimpleVector result = new SimpleVector();
tmp.set(boundingBox[0],boundingBox[2],boundingBox[4]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!isInBounds(result,0,width,0,height)){
moveOut = true;// we need to move camera out
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[0],boundingBox[2],boundingBox[5]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[0],boundingBox[3],boundingBox[4]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[0],boundingBox[3],boundingBox[5]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[1],boundingBox[2],boundingBox[4]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[1],boundingBox[2],boundingBox[5]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[1],boundingBox[3],boundingBox[4]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

tmp.set(boundingBox[1],boundingBox[3],boundingBox[5]);
Interact2D.project3D2D(cam, fb,tmp,result);
if(!moveOut && !isInBounds(result,0,width,0,height)){
moveOut = true;
moveIn = false;
}else if(moveIn && !isInBounds(result,BORDER_SIZE,width - BORDER_SIZE,BORDER_SIZE,height - BORDER_SIZE)){
moveIn = false;
}

if(moveOut){
cam.moveCamera(Camera.CAMERA_MOVEOUT, CAMERA_MOVE_STEP);
}else if(moveIn){
cam.moveCamera(Camera.CAMERA_MOVEIN, CAMERA_MOVE_STEP);
}
}

private boolean isInBounds(SimpleVector point,float minx,float maxx,float miny, float maxy){
if(point == null) return false;
if(point.x < minx || point.x > maxx || point.y < miny || point.y > maxy)return false;
return true;
}


private float getTileX(Tile tile){
return tile.x*(TILE_MARGIN + 2*TILE_SCALE);
}

private float getTileY(Tile tile){
return tile.y*(TILE_MARGIN + 2*TILE_SCALE);
}

private float getTileZ(Tile tile){
return tile.z*(TILE_MARGIN + 2*TILE_SCALE);
}

private void processCameraMovement(){
if(world == null || Math.abs(xImpulse) <= 2*resist && Math.abs(yImpulse) <= 2*resist) return;
float xDir = 0;
if (isCameraRotatingX()) {
xDir = xImpulse*period;
}
float yDir = 0;
if (isCameraRotatingY() ) {
yDir = yImpulse*period;
}
rotateCamera(xDir, yDir);
}

private void rotateCamera(float xDir, float yDir){
Camera cam = world.getCamera();
SimpleVector center = model3D.getTransformedCenter();
float dist = center.distance(cam.getPosition());
float skyDist = center.distance(skyPlane.getTransformedCenter());
cam.setPosition(center);

center = model3D.getTransformedCenter();
center.sub(skyPlane.getTransformedCenter());
skyPlane.translate(center);

cam.rotateX(xDir);
cam.rotateY(yDir);

cam.moveCamera(Camera.CAMERA_MOVEOUT, dist);

center = model3D.getTransformedCenter();
SimpleVector dir = cam.getDirection();
dir.scalarMul(-1);
dir.add(cam.getUpVector());
SimpleVector tmp = cam.getSideVector();
tmp.scalarMul(-1);
dir.add(tmp);
dir.scalarMul(SUN_DISTANCE);
center.add(dir);
sun.setPosition(center);

dir = cam.getDirection();
dir.scalarMul(skyDist);
skyPlane.translate(dir);
skyPlane.align(cam);
}

public Tile pick(int x, int y){
Camera cam = world.getCamera();
SimpleVector dir=Interact2D.reproject2D3DWS(cam, fb, x, y);
Object[] res=world.calcMinDistanceAndObject3D(cam.getPosition(), dir, 10000 /*or whatever*/);
if(res[1] == null) return null;
return (Tile)((Object3D)res[1]).getUserObject();
}


private boolean isCameraRotatingX(){
return Math.abs(xImpulse) > 2*resist ? true: false;
}

private boolean isCameraRotatingY(){
return Math.abs(yImpulse) > 2*resist ? true: false;
}

private boolean isCameraRotating(){
return isCameraRotatingX() || isCameraRotatingY();
}

public void handleMove(float xDir,float yDir){
rotateCamera(xDir, yDir);
}

public void handlePush(float xImp,float yImp){
xImpulse = xImp;
yImpulse = yImp;
}

public void handleStop(){
xImpulse = 0;
yImpulse = 0;
}
// ------------------- listeners --------------------------------
@Override
public void onTileDeselected(Tile tile) {
deselect(tile);
}

@Override
public void onTilePareRemoved(Tile tile0, Tile tile1) {
remove(tile0);
remove(tile1);
}

@Override
public void onTileSelected(Tile tile) {
select(tile);
}

@Override
public void onModelShuffaled() {
if(isWorldInited){
initModel();
}

}

}


I have some experience in developing apps for android but am really confused with this exception, so any help will be great.