B4A Library libGDX - Game Engine

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One of the best game engines for Android is now available to B4A users. Unleash your creativity!

You can read a description of this library in this guide.

Download for B4A v10.60 and older (4 MB)
Download for B4A v10.70 and newer (4 MB)

Starting from version 1.13, the library is compiled with Java 8, and thus requires a recent version of B4A and Java 8+.
To install the library, copy the .jar file and the .xml file in your libraries folder.

This library is not compatible with the Debug mode. Ensure that you always compile in Release mode.

Download also the examples and templates.

You can reduce the weight of the library if you want to keep your APK file as small as possible. Read this post to learn how to create your Lite version.

Tutorials:
How to make games
Introduction to the libGDX library
PacDroid: from scratch to fun
Shaders

Take also a look at the Cloney Bird tutorial by andymc.

Plugins:
Box2DLights
SpecialFX

Versions:
v1.14:
- I fixed a bug when Looping was changed during the execution of a sound;
- I added the RenderImageLayerAt function to all map renderers;
- I added the support of the new packaging tool used by B4A v10.70 (this mainly fixes the problem of / in paths of internal assets);
- I updated the manifest of all examples.

v1.13:
- I fixed a bug when the device was rotated (the Timer thread, for example, was not disposed which caused a problem in lgGestureDetector);
- I added two functions for Tiled maps: renderImageLayerAt and renderTileLayerAt.

v1.12:
- I added the .so libraries for 64 bits CPU;
- I added the PinchStop event to lgGestureDetector;
- I added the Orientation property to lgBox2DTransform;
- I fixed minor bugs.

v1.11:
- I fixed several bugs;
- I removed the unwanted delay after a change of screen in the Render event;
- I added the lgAsyncExecutor and lgAsyncTask classes;
- I added the missing file for the Progression demo;
- I updated the Freetype library (.so).

v1.10:
- I fixed several bugs;
- I added the support of expansion files: classes lgZipResourceFile and lgZipEntry, functions lgFiles.SetAPKExpansion and lgFiles.ExpansionFile (untested);
- I added a HashCode function to all lg...Array classes;
- I added a dozen of predefined colors to lgColor;
- I added the "raw_y" property to lgMapObjects;
- I added the grow, growX and growY functions to lgScn2DTableCell;
- I added the lerpAngle and lerpAngleDeg functions to lgMathUtils;
- I improved Atan2 in lgMathUtils;
- the collision objects of TMX tiles are now accessible via the Objects property of lgMapAnimatedTiledMapTile and lgMapStaticTiledMapTile;
- I added two new examples: Progression and Map_Box2D;
- I updated the manifest of most examples and templates.

v1.09:
- I fixed bugs, notably a major bug that crashed sometimes the game in the Render event handler when the current screen is changed;
- I added getColumnWidth and getRowHeight to lgScn2DTable and all classes that inherit from lgScn2DTable;
- I added the defaults function to lgScn2DTableCell;
- TMX files are loaded faster.

1.08:
- I fixed bugs;
- I added the lgFontGeneratorParameters class;
- I added CreateFontWithParam to lgFontGenerator;
- lgFontGenerator can add now a border and a shadow to the generated fonts (via CreateFontWithParam);
- I added Initialize2, LabelAlign and LineAlign to lgScn2DLabel;
- I added SetStateWithoutEvent to lgScn2DButton and lgScn2DTextButton;
- I added TitleLabel and TitleTable to lgScn2DWindow (this deprecates ButtonTable, Title, TitleWidth and TitleAlignment);
- I added getIndex to lgMapLayers and lgMapObjects;
- I added Target to actions of Scene2D;
- I removed Print from lgScn2DGroup (use Log(myGroup) instead);
- lgMapTiledMapImageLayer uses now float values for position;
- lgNinePatch uses now float values for paddings;
- lgPixmapPacker and lgPixmapPackerPage were rewritten (the many changes will break your existing code).

1.07:
- I fixed a few bugs, as usual;
- I added InitializeTransparentView to LibGDX;
- I added the lgKTXTextureData class to support the KTX and ZKTX file formats;
- I added a new demo: Format_KTX;
- I added argb8888 and argb8888ToColor to lgColor
- I added the lgMapAtlasTmxMapLoaderParameters class;
- I added Initialize3 and Load2 to lgMapAtlasTmxMapLoader;
- I added LoadExternal and IsInitialized to lgMapTmxMapLoader;
- I added FrameTiles to lgMapAnimatedTiledMapTile;
- I added a Tag property to lgSprite;
- I added hasOppositeDirection, hasSameDirection, isCollinear, isOnLine, isPerpendicular, AngleRad and rotateRad to lgMathVector2;
- I added rotateRad to lgMathMatrix4;
- I added clamp4, log, log2, Randomize, randomInt, randomInt2, randomSign, randomTriangular and randomTriangular2 to lgMathUtils;
- the random number generator of lgMathUtils uses now the xorshift128+ algorithm;
- I renamed Create2 to Combine in lgMesh;
- I removed the Create and Create3 functions from lgMesh;
- I removed the deprecated Color property from lgVertexAttributesUsage;
- it is possible now to change the KeyFrames array of lgAnimation after its initialization.

v1.06:
- I fixed a few bugs;
- I added a Texture property to lgSprite;
- I added the MotorJoint type to lgBox2DWorld;
- I added GetFixture to lgBox2DBody;
- I added Initialize3 to lgShapeRenderer to allow the use of custom shader programs;
- I added ScaleEffect to lgParticleEffect;
- I added CleanUpBlendFunction to lgParticleEmitter;
- I added scl2 to lgMathVector2;
- I added IsEnabled to lgGLProfiler;
- I added Percent, VisualPercent and VisualInterpolation to lgScn2DProgressBar;
- I added Percent, VisualPercent, VisualInterpolation and VisualInterpolationInverse to lgScn2DSlider;
- I added isLeftEdge, isRightEdge, isTopEdge, isBottomEdge to lgScn2DScrollPane;
- The Reset function of lgScn2DTableCell sets now all constraints to their default values;
- I modified the Map_Hexagonal example to display the coordinates of the touched hex.

v1.05:
- I fixed two bugs;
- the latest TMX format of Tiled Map Editor is now properly decoded (with support of animated tiles and image layers);
- I added the RenderImageLayer function to the map renderers;
- I added the lgMapTiledMapImageLayer class for the image layer of tiled maps;
- I added the OffsetX and OffsetY properties to lgMapAnimatedTiledMapTile and lgMapStaticTiledMapTile;
- I added the CurrentFrame and CurrentFrameIndex properties to lgMapAnimatedTiledMapTile;
- I added the FinishLoadingAsset function to lgAssetManager;
- I added the SetAlpha function to lgBitmapFontCache;
- I added FixtureCount and GetAllFixtures to lgBox2DWorld;
- I added the ResetOnTouchUp property to lgTouchpad;
- I removed Scale and Div from lgMathVector3 because these functions were deprecated.

v1.04:
- I fixed various bugs, notably a bug affecting the Backspace key on the virtual keyboard of some devices;
- I added the missing OpenGL functions in lgGL;
- I added the KeepWithinStage function to lgDragAndDrop;
- I added the dampingRatio and frequencyHz fields to lgBox2DWeldJointDef;
- I added the DampingRatio and Frequency properties to lgBox2DWeldJoint;
- I added the Line6 function to lgShapeRenderer;
- I added VisualScrollPercentX, VisualScrollPercentY and FlickScrollTapSquareSize to lgScn2DScrollPane;
- the LineHeight property of BitmapFonts can be modified;
- I updated the .so files;
- I added an example: Sensors.

v1.03:
- I fixed various bugs;
- I added the VertexColor property to lgPolygonSprite;
- I added the Equals function to lgArray;
- I renamed Ellipse to Ellipsis in lgScn2DLabel;
- I improved the code of lgPixmapIO (less memory used, PNG with compression);
- I fixed a problem with the fragment shaders of two examples.

v1.02:
- I fixed 3 bugs in lgScn2dTable and a few others in other classes;
- I added 4 examples using shaders;
- I removed the lgDefaultGroupStrategy class because it was useless and changed the initialization of lgDecal objects;
- I added the SetRotation function to lgDecal;
- I added the Tint function to lgBitmapFontCache;
- I added the Cancel and Reset functions to lgGestureDetector;
- I added the IsKeyJustPressed function to lgInput;
- I added the Colinear and EnsureCCW functions to lgMathGeometryUtils;
- I added the Equals function to lgMathGridPoint2, lgMathGridPoint3 and lgMathRay;
- I added the IntersectRayRay and DistanceLinePoint2 functions to lgMathIntersector;
- I added the Extract4x3Matrix function to lgMathMatrix4;
- I added the WindowSize property to lgMathWindowedMean;
- I added the IsDrawing function to lgShapeRenderer;
- I added the ColorUnpacked field to lgVertexAttributesUsage;
- I added the Clear function to lgScn2DButtonGroup;
- I added the CancelTouchFocus property to lgScn2DDragAndDrop;
- I added the Rows, Columns, BackgroundTop, BackgroundLeft, BackgroundBottom, and BackgroundRight properties to lgScn2DTable;
- I added the ClearActor function to lgScn2dTableCell;
- I added the ActionsRequestRendering property to lgScn2DStage;
- I renamed CancelTouchFocus2 to CancelTouchFocusExcept in lgScn2DStage;
- I removed the Clear function from lgScn2dTableCell;
- The color markups are now supported by lgScn2dLabel and lgScn2dWindow (title).

v1.01:
- I fixed a handful of minor bugs and a big bug affecting the screen events;
- I added IsDrawing in lgSpriteBatch.

v1.0:
- I fixed bugs in various classes;
- I rewrote big chunks of internal graphics classes;
- the TMX map loaders are now able to read the Rotation property;
- the FrameDuration property of lgAnimation can now be changed during the animation;
- I added an Initialize function to lgMapAnimatedTiledMapTile to be able to set dynamically an animated tile;
- I added two new classes for debugging: lgGLProfiler and lgScn2DDebugRenderer;
- I added DebuggingEnabled and DebugColor to all actors of Scene2D;
- I added ChildrenDebuggingEnabled to all groups of Scene2D;
- I added CellDebugColor to lgScn2DTable and removed all its debug functions;
- I added SetCenterPosition, CenterX and CenterY to all actors of Scene2D;
- I replaced the Widget word by Actor in lgScn2DTableCell;
- I added the Equals and HashCode functions to a few lgMath classes;
- I added the ApproxLength function to lgMathBezier, lgMathBSpline and lgMathCatmullRomSpline;
- I added Set3, SetPosition2, Contains2, Circumference and Area to lgMathCircle;
- I added Set3, SetPosition2, Circumference and Area to lgMathEllipse;
- I added Merge2, Area and Perimeter to lgMathRectangle;
- I added Len and Len2 to lgMathSegment;
- I added Volume and SurfaceArea to lgMathSphere;
- I added Interpolate to lgMathVector2 and lgMathVector3;
- I added the following functions to lgMathMatrix4: mulLeft, Set2, Set3, Set4, Set5, Set6, ScaleX, ScaleY, ScaleZ, ScaleXSquared, ScaleYSquared, ScaleZSquared;
- I added a LoadMipMap event and replaced UseHardwareMipMap by Get/SetGenerationMethod in lgMipMapGenerator;
- Box2D has now its own .so library;
- I added Separations to lgBox2DWorldManifold;
- I added the following functions to lgBox2DEdgeShape: Vertex0, SetVertex0, SetVertex0_xy, HasVertex0, Vertex3, SetVertex3, SetVertex3_xy, HasVertex3;
- I added LocalAxisA to lgBox2DPrismaticJoint;
- I added two new classes to Box2D: lgBox2DMotorJoint and lgBox2DMotorJointDef;
- I added the LoadTextureWithParam function to lgAssetManager and the related lgTextureLoaderParam class;
- I added two new properties (Normalized, Type) and a function (HashCode) to lgVertexAttribute;
- I renamed Color to ColorPacked in lgVertexAttribute;
- I renamed Loop to Repeat in lgSound;
- I renamed consumeCompressedData to consumeCustomData in all TextureData classes;
- I protected some important classes against a repeated initialization to avoid memory leaks and side effects;
- I added a Scene2D_EventsHierarchy demo and modified the following examples: BitmapFont, FrameBuffer, Map_tIDE and Scene2D_Table.

v0.99:
- I fixed numerous bugs, especially in Scene2D where the listeners did not work as expected and actors were not fully re-initialized when Initialize was called again;
- I set to Null the internal objects of classes after a call to Dispose;
- I added the following functions:
+ IsInitialized where it was still missing;​
+ Move to lgArray;​
+ ComputeScaleForPixelHeight to lgBitmapFont;​
+ SetNameForColor, GetColorByName and SetAlpha to lgColor;​
+ Clear to lgMapLayers;​
+ Lerp to lgMathUtils;​
+ Load3 and LoadEmitterImages3 to lgParticleEffect;​
+ SetString to lgScn2DLabel;​
+ Initialize4 to lgScn2DSpriteDrawable, lgScn2DTextureRegionDrawable and lgScn2DTiledDrawable;​
+ UpdateMatrices to lgShapeRenderer;​
+ SetCenterX, SetCenterY and SetCenter to lgSprite;​
- I added a ChildrenCount property to lgScn2DGroup;
- I added a Draw event to lgScn2DImage and lgScn2DLabel;
- I added a Disabled property to lgScn2DScrollPane;
- I added the following predefined colors to lgColor: Olive, Purple, Maroon, Teal, Navy;
- I renamed the alpha function to to255 in lgColor;
- lgBitmapFont and lgBitmapFontCache now support in-string colored text through a simple markup language (see the demo);
- I added the MarkupEnabled property to lgBitmapFont;
- I added a BitmapFont demo;
- I modified the FrameBuffer demo;
- I removed the yUp and yDown parameters from the tiled map loaders and renderers (yUp is now always true);
- I removed Rotation and rotateBy from lgScn2DLabel, lgScn2DList, lgScn2DSelectBox and lgScn2DTouchpad because they were not effective.

v0.98:
- I fixed a bug affecting the scaling and rotation of lgScn2DImage;
- I fixed a bug in lgBox2DParticleEmitter;
- I fixed a bug in lgScn2DButton;
- I added the lgFrameBuffer class and a FrameBuffer demo;
- I added the IsInitialized function where it was missing;
- I added the PolygonRegion type to lgAssetManager;
- I added a Payload parameter to the SrcDragStop event of lgScn2DDragAndDrop;
- I added the Draw2 function to lgScn2DSpriteDrawable;
- I added the Set3 function to lgMathMatrix3.

v0.97:
- I fixed a few bugs (the immersive mode works now as expected);
- I found a solution for the repetition of tiles, so I added two properties (RepeatX, RepeatY) to lgMapTiledMapLayer and I modified the Map demos.
- I added an IsInitialized function to 15 classes;
- I added a RemoveRange function to all the lgArray classes;
- I added the Fling function to lgScn2DScrollPane;
- I added the IsVisualPressed function and the VisualPressedDuration property to lgScn2DClickListener.

v0.96: Major update!
In this version, I:
- removed all the code supporting OpenGL ES 1.x
- fixed a few bugs
- added new classes for decals (2D objects in 3D space): lgDecal, lgDecalBatch, lgCameraGroupStrategy, lgDefaultGroupStrategy, lgSimpleOrthoGroupStrategy
- added an example for decals
- removed the Mesh example as it cannot work with OpenGL 2 without being rewritten
- added the lgScn2DProgressBar class and modified the Scene2D_TextFieldsAndSliders example to show how to use it
- added the IsInitialized function to a dozen of classes
- added these functions:
lgBox2DWheelJoint: isMotorEnabled
lgFontGenerator: CreateFont5, CreateFont6 (for mip maps and filters)
lgMathGeometryUtils: polygonArea, triangleArea
lgMathMatrix3: getScale, getTranslation, setToRotation2, setToRotation3, setToRotationRad, rotateRad
lgMathMatrix4: det3x3, setToRotationRad, setTranslation
lgMathUtils: isEqual, isEqual2, isZero, isZero2
lgMesh: CalculateRadius, CalculateRadius2, CalculateRadiusSquared
lgScn2DDragAndDrop: SetTouchOffset
lgSprite: SetOriginCenter
- added these properties:
lgBox2DJoint: CollideConnected
lgBox2DDistanceJoint, lgBox2DFrictionJoint, lgBox2DRopeJoint, lgBox2DWeldJoint: LocalAnchorA, LocalAnchorB
lgBox2DGearJoint: Joint1, Joint2
lgBox2DPrismaticJoint: LocalAnchorA, LocalAnchorB, MaxMotorForce, ReferenceAngle
lgBox2DWheelJoint: LocalAnchorA, LocalAnchorB, LocalAxisA
lgMathMatrix3: Rotation, RotationRad
lgScn2DActor: isTouchable
lgScn2DScrollPane: ScrollHeight, ScrollWidth, VariableSizeKnobs
lgScn2DWindow: ButtonTable, Resizable, ResizeBorder, TitleWidth
- renamed the functions Translate -> MoveBy, Rotate -> RotateBy and Size -> SizeBy of the lgScn2DActor class
- removed toScreenCoordinates from lgStage and toWindowCoordinates from lgScissorStack
- removed the yDown parameter from ComputePolygon and ComputePolygon2 in the lgMathConvexHull class
- improved a bit the help text of a few functions

v0.95:
Bugfixes and minor improvements
New classes: lgFloatArray, lgIntArray, lgShortArray
The lgMathConvexHull and lgMathEarClippingTriangulator classes are now usable
New functions:
- lgPerspectiveCamera: GetPickRay
- lgScn2DStage: SetViewport2
- lgMathFrustum: pointInFrustum2, sphereInFrustum2, sphereInFrustumWithoutNearFar2
- lgBox2DChainShape: createLoop2
- lgMathIntersector: intersectSegments2
- lgMathVector2: isUnit, isUnit2, isZero, isZero2
- lgMathVector3: set2, isUnit2, isZero2
New configuration setting: useImmersiveMode (for Kitkat)

v0.94:
Bugfixes (including a serious bug with the listeners of Scene2D)
New classes: lgMapTmxMapLoaderParameters and lgMipMapGenerator
New functions:
- lgAnimation: KeyFrames
- lgAssetManager: LoadTMXWithParam
- lgBitmapFontCache: SetColors, SetColors2, SetColorsRGBA
- lgGestureDetector: Initialize2
- lgMapTmxMapLoader: Initialize3, Load2
- lgMathVector2: Rotate90
- lgMesh: UpdateVertices, UpdateVertices2
- lgMusic: Duration, Position
- lgScn2DClickListener: inTapSquare2
- lgScn2DList: ItemHeight
- lgShapeRenderer: RectLine
- lgSocket: RemoteAddress
- lgSprite: Alpha, SetFlip
New parameters: ListBox and ScrollPane styles in lgScn2DSelectBoxStyle.Initialize
New example: Filters
Modified example: Map_tIDE (I fixed the visual issues)
New configuration setting: disableAudio

v0.93:
Bugfixes (including the problem reported for the Get...List functions of Box2D)
Class rewritten: lgTexture (some functions have been added, some have been removed)
New configuration setting: useGLSurfaceViewAPI18 (for Gingerbread and older versions)
New functions: lgFileHandle.equals, lgFileHandle.hashCode, lgShapeRenderer.Triangle2
New class: lgPerspectiveCamera (for 3D)
New example: ShapeRenderer
Modified example: Perf_Skaters (the background scrolls endlessly now)

0.92:
Minor bugfixes
Internal changes for texture handling
Viewport parameters added to CalculateScissors in lgScissorStack
New function in lgScn2DScrollPane: setScrollBarPositions
New function in lgMathVector2: epsilonEquals2
New function in lgMathIntersector: intersectRectangles
Initialize3 and FindDirectionForIsoView functions removed from lgOrthographicCamera

0.91:
Bugfixes (including the problem reported for tIDE properties)
New event for gesture detector: PanStop
New Initialize function for Bitmapfont to allow to flip the font
New Rect functions for the ShapeRenderer
New class: lgMapIsometricStaggeredMapRenderer (for staggered isometric maps)
New function for lgScn2dScrollPane: Cancel
lgMathBezier and lgMathBresenham2 are now fully usable
New functions in lgMathIntersector
A few internal changes to improve performance and stability

0.9:
Bugfixes
New class: lgArray (ordered array with an initial capacity)
Many Lists have been replaced by lgArray for a better performance and more possibilities
Improved documentation (mainly in lgMath and lgSprite classes)
lgMathBSpline and lgMathCatmullRomSpline are now fully usable
New example: SplinePath
New function for particle effects and particle emitters: BoundingBox
New property for lgScn2DLabel: Ellipse

0.8:
First release
 
Last edited by a moderator:

wonder

Expert
Licensed User
Longtime User
Hello Informatix,

I've ported an HTML5 3D-Starfield Example to B4A / LibGDX.
Everything runs perfectly smooth without any issues, except for one minor detail.

The star behavior in the z-axis is different than it should be, unless I delay the start of the 3D-Starfield drawing (in LG_Render) for a few seconds.
B4X:
Sub Process_Globals
    Dim Engine_Start_Timestamp = DateTime.Now As Long
Ens Sub

...

Sub LG_Render
    ...
    If DateTime.Now - Engine_Start_Timestamp > 5000 Then Draw_Starfield
    ...
End Sub
I've also noticed abnormal behavior (not exactly the same, but still abnormal) in my "Project Ryu" game, unless I add this delay workaround.
I've been reading your tutorials back and forth and trying to understand if there is a synchronization problem between the GDX thread and the main thread.

Another solution I tried was to add 2 boolean flags (Globals_Ready = True and LG_Ready = True) at the end of Sub Globals and Sub LG_Create.
B4X:
Sub Process_Globals
    Dim Globals_Ready, LG_Ready = False as Boolean
    ...
End If

Sub Globals
    ...
    ...
    ...
    ...
    Globals_Ready = True

End If

Sub LG_Create
    ...
    ...
    ...
    ...
    LG_Ready = True
End If

Sub LG_Render
    ...
    If Globals_Ready = True and LG_Ready = True Then Draw_Starfield
    ...
End Sub
No success, the abnormal behavior still happens.

I can record a small video to illustrate the problem if necessary.
 

Informatix

Expert
Licensed User
Longtime User
Hello Informatix,

I've ported an HTML5 3D-Starfield Example to B4A / LibGDX.
Everything runs perfectly smooth without any issues, except for one minor detail.

The star behavior in the z-axis is different than it should be, unless I delay the start of the 3D-Starfield drawing (in LG_Render) for a few seconds.
B4X:
Sub Process_Globals
    Dim Engine_Start_Timestamp = DateTime.Now As Long
Ens Sub

...

Sub LG_Render
    ...
    If DateTime.Now - Engine_Start_Timestamp > 5000 Then Draw_Starfield
    ...
End Sub
I've also noticed abnormal behavior (not exactly the same, but still abnormal) in my "Project Ryu" game, unless I add this delay workaround.
I've been reading your tutorials back and forth and trying to understand if there is a synchronization problem between the GDX thread and the main thread.

Another solution I tried was to add 2 boolean flags (Globals_Ready = True and LG_Ready = True) at the end of Sub Globals and Sub LG_Create.
B4X:
Sub Process_Globals
    Dim Globals_Ready, LG_Ready = False as Boolean
    ...
End If

Sub Globals
    ...
    ...
    ...
    ...
    Globals_Ready = True

End If

Sub LG_Create
    ...
    ...
    ...
    ...
    LG_Ready = True
End If

Sub LG_Render
    ...
    If Globals_Ready = True and LG_Ready = True Then Draw_Starfield
    ...
End Sub
No success, the abnormal behavior still happens.

I can record a small video to illustrate the problem if necessary.
Could you post the whole code?
 

wonder

Expert
Licensed User
Longtime User
Here's all the relevant parts, I hope I'm not missing anything.
I'll post a small video later.
B4X:
Sub Process_Globals
    Dim Creation = DateTime.Now as Long
    ...
End Sub


Sub Globals
        Dim ball_speed = 80%x As Float

        Dim Ball_Width = 4%x As Float
        Dim Ball_Height = Ball_Width As Float
        Dim Ball_Left = 50%x - (Ball_Width / 2) As Float
        Dim Ball_Top = 50%y - (Ball_Height / 2) As Float 
        Dim Ball_Last_Left As Float
        Dim Ball_Last_Top As Float


    'LibGDX Setup
        Dim lGdx As LibGDX
        Dim Gl As lgGL
        Dim Camera As lgOrthographicCamera
        Dim Batch As lgSpriteBatch
        Dim GLView As View

    'Color Mixer
        Dim temp_color As lgColor
    
    'LibGDX Textures
        Dim Tex001 as lgTexture
        Dim Tex002 as lgTexture
        ...

    'LibGDX Objects
        Dim Obj001 As lgTextureRegion
        Dim Obj002 As lgTextureRegion
        ...

    'Starfield
        Dim MAX_DEPTH = 32 As Float
        Dim number_of_stars = 64 As Float    
        Dim initial_star_speed_factor = 100 As Float
        Dim star_speed_factor = initial_star_speed_factor As Float
        Dim star_speed_change_timestamp As Long
        Dim star_speed_change_duration As Int
        Dim star_x(number_of_stars) As Float
        Dim star_y(number_of_stars) As Float
        Dim star_z(number_of_stars) As Float
        Dim smin = -25 As Int
        Dim smax =  26 As Int    
 
        For i = 0 To (number_of_stars - 1)
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)
            star_z(i) = Rnd(1, MAX_DEPTH)
        Next
End Sub

Sub Activity_Create(FirstTime as Boolean)
    ...
    ...
    'Initialize libGDX
        GLView = lGdx.InitializeView("LG")  
        Activity.AddView(GLView, 0%x, 0%y, 100%x, 100%y)
    ...
    ...
End Sub

Sub LG_Create
    Batch.Initialize
    'Initialize Textures
        Tex001.Initialize("tex001.png")
        Tex002.Initialize("tex002.png")
        ...
    'Initialize Objects
        Obj001.InitializeWithTexture(Tex001)
        Obj002.InitializeWithTexture(Tex002)
        ...

        Obj001.Flip(False, True)
        Obj002.Flip(False, True)

    temp_color = Batch.color
End Sub


Sub LG_Resize(Width As Int, Height As Int)
    'Sets the camera viewport
        Camera.Initialize
        Camera.SetToOrtho2(True, lGdx.graphics.Width, lGdx.Graphics.Height)
End Sub


Sub LG_Render
    'Clears the screen
        Gl.glClear(Gl.GL10_COLOR_BUFFER_BIT)
                            
    'Updates the matrices of the camera
        Camera.Update

    'Uses the coordinate system specified by the camera
        Batch.ProjectionMatrix = Camera.Combined
        
    'Step Setup
        LGStep = lGdx.Graphics.DeltaTime

    'Main GDX Cycle
        If DateTime.Now - Creation >= 5000 Then
            Batch.Begin
            LG_Draw_Starfield
            ...
            Batch.End
        End If
End Sub


Sub LG_Draw_Starfield
    For i = 0 To (number_of_stars - 1)

        If (DateTime.Now - star_speed_change_timestamp) >= star_speed_change_duration Then star_speed_factor = initial_star_speed_factor
    
        star_z(i)= star_z(i) - (ball_speed * LGStep) / star_speed_factor
        If star_z(i) <= 0 Then
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)        
            star_z(i) = MAX_DEPTH        
        End If
        Dim k  = 128 / star_z(i) As Float
        Dim px = star_x(i) * k + 50%x + ((1/6) * (50%x - Ball_Left)) As Float
        Dim py = star_y(i) * k + 50%y + ((1/9) * (50%y - Ball_Top )) As Float      

        If px >= 0%x AND px <= 100%x AND py >= 0%x AND py <= 100%y Then
            Dim size = (1 - (star_z(i) / 32.0)) * 5 As Float
            Dim shade = (1 - (star_z(i) / 32.0)) * 255 As Float        
        
            If game_mode = "INTRO" OR game_mode = "MENU" Then shade = shade / 2
        
            ARGB(0) = (shade / 255)
            Dim apply_shade As lgColor                        
            Batch.color = apply_shade.setRGBA(ARGB(1)/255, ARGB(2)/255, ARGB(3)/255, ARGB(0))
                    
            'Draw a single star
                Batch.DrawRegion2(Star, px, py, size * 10, size * 10)            
                    
        End If
    Next
    Batch.color = temp_color
End Sub


Sub LG_Dispose
    'Dispose All Sounds
        ...
    'Dispose All Textures
        ...
End Sub


Sub LG_Pause
End Sub


Sub LG_Resume
End Sub
 
Last edited:

Informatix

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Here's all the relevant parts, I hope I'm not missing anything.
I'll post a small video later.
B4X:
Sub Process_Globals
    Dim Creation = DateTime.Now as Long
    ...
End Sub


Sub Globals
        Dim ball_speed = 80%x As Float

        Dim Ball_Width = 4%x As Float
        Dim Ball_Height = Ball_Width As Float
        Dim Ball_Left = 50%x - (Ball_Width / 2) As Float
        Dim Ball_Top = 50%y - (Ball_Height / 2) As Float
        Dim Ball_Last_Left As Float
        Dim Ball_Last_Top As Float


    'LibGDX Setup
        Dim lGdx As LibGDX
        Dim Gl As lgGL
        Dim Camera As lgOrthographicCamera
        Dim Batch As lgSpriteBatch
        Dim GLView As View

    'Color Mixer
        Dim temp_color As lgColor
   
    'LibGDX Textures
        Dim Tex001 as lgTexture
        Dim Tex002 as lgTexture
        ...

    'LibGDX Objects
        Dim Obj001 As lgTextureRegion
        Dim Obj002 As lgTextureRegion
        ...

    'Starfield
        Dim MAX_DEPTH = 32 As Float
        Dim number_of_stars = 64 As Float   
        Dim initial_star_speed_factor = 100 As Float
        Dim star_speed_factor = initial_star_speed_factor As Float
        Dim star_speed_change_timestamp As Long
        Dim star_speed_change_duration As Int
        Dim star_x(number_of_stars) As Float
        Dim star_y(number_of_stars) As Float
        Dim star_z(number_of_stars) As Float
        Dim smin = -25 As Int
        Dim smax =  26 As Int   

        For i = 0 To (number_of_stars - 1)
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)
            star_z(i) = Rnd(1, MAX_DEPTH)
        Next
End Sub

Sub Activity_Create(FirstTime as Boolean)
    ...
    ...
    'Initialize libGDX
        GLView = lGdx.InitializeView("LG") 
        Activity.AddView(GLView, 0%x, 0%y, 100%x, 100%y)
    ...
    ...
End Sub

Sub LG_Create
    Batch.Initialize
    'Initialize Textures
        Tex001.Initialize("tex001.png")
        Tex002.Initialize("tex002.png")
        ...
    'Initialize Objects
        Obj001.InitializeWithTexture(Tex001)
        Obj002.InitializeWithTexture(Tex002)
        ...

        Obj001.Flip(False, True)
        Obj002.Flip(False, True)

    temp_color = Batch.color
End Sub


Sub LG_Resize(Width As Int, Height As Int)
    'Sets the camera viewport
        Camera.Initialize
        Camera.SetToOrtho2(True, lGdx.graphics.Width, lGdx.Graphics.Height)
End Sub


Sub LG_Render
    'Clears the screen
        Gl.glClear(Gl.GL10_COLOR_BUFFER_BIT)
                           
    'Updates the matrices of the camera
        Camera.Update

    'Uses the coordinate system specified by the camera
        Batch.ProjectionMatrix = Camera.Combined
       
    'Step Setup
        LGStep = lGdx.Graphics.DeltaTime

    'Main GDX Cycle
        If DateTime.Now - Creation >= 5000 Then
            Batch.Begin
            LG_Draw_Starfield
            ...
            Batch.End
        End If
End Sub


Sub LG_Draw_Starfield
    For i = 0 To (number_of_stars - 1)

        If (DateTime.Now - star_speed_change_timestamp) >= star_speed_change_duration Then star_speed_factor = initial_star_speed_factor
   
        star_z(i)= star_z(i) - (ball_speed * LGStep) / star_speed_factor
        If star_z(i) <= 0 Then
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)       
            star_z(i) = MAX_DEPTH       
        End If
        Dim k  = 128 / star_z(i) As Float
        Dim px = star_x(i) * k + 50%x + ((1/6) * (50%x - Ball_Left)) As Float
        Dim py = star_y(i) * k + 50%y + ((1/9) * (50%y - Ball_Top )) As Float     

        If px >= 0%x AND px <= 100%x AND py >= 0%x AND py <= 100%y Then
            Dim size = (1 - (star_z(i) / 32.0)) * 5 As Float
            Dim shade = (1 - (star_z(i) / 32.0)) * 255 As Float       
       
            If game_mode = "INTRO" OR game_mode = "MENU" Then shade = shade / 2
       
            ARGB(0) = (shade / 255)
            Dim apply_shade As lgColor                       
            Batch.color = apply_shade.setRGBA(ARGB(1)/255, ARGB(2)/255, ARGB(3)/255, ARGB(0))
                   
            'Draw a single star
                Batch.DrawRegion2(Star, px, py, size * 10, size * 10)           
                   
        End If
    Next
    Batch.color = temp_color
End Sub


Sub LG_Dispose
    'Dispose All Sounds
        ...
    'Dispose All Textures
        ...
End Sub


Sub LG_Pause
End Sub


Sub LG_Resume
End Sub
I notice that if star_z(i) = 0 then you have a division by zero.
 

wonder

Expert
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Longtime User
I notice that if star_z(i) = 0 then you have a division by zero.
Isn't that prevented by:
B4X:
If star_z(i) <= 0 Then
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)      
            star_z(i) = MAX_DEPTH      
End If
Dim k = 128 / star_z(i) AsFloat
MAX_DEPTH is set to 32 in Sub Globals. The only way for MAX_DEPTH to be zero is if the LG_Render is started before the Sub Globals...

Anyway, I'm working on the video.
 

Informatix

Expert
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Longtime User
Isn't that prevented by:
B4X:
If star_z(i) <= 0 Then
            star_x(i) = Rnd(smin, smax)
            star_y(i) = Rnd(smin, smax)     
            star_z(i) = MAX_DEPTH     
End If
Dim k = 128 / star_z(i) AsFloat
MAX_DEPTH is set to 32 in Sub Globals. The only way for MAX_DEPTH to be zero is if the LG_Render is started before the Sub Globals...

Anyway, I'm working on the video.
Ah yes, sorry. I have to try the code if I want to understand where's the issue.
 

wonder

Expert
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Longtime User
I've tried to record the video with my mobile phone, but the quality is terrible.
Instead I've tried to illustrate the problem:
Untitled.png

By "appear" I mean "move". The stars move in compact blocks in the z-axis, instead of being evenly spread.

One thing I've noticed, this doesn't happen in the same way in all devices.
Usually, the faster the device is, the most unlikely is it to happen without the "delay method".
 

wonder

Expert
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Longtime User
I found the solution for the problem I mentioned in my previous posts.

It seems that the value of lgdx.Graphics.DeltaTime is zero during the first few seconds an app is started. Depending on your code, this causes weird behaviour, like frozen sprites or divisions by zero. In my case I think it might have been a division by zero since I was using (1 / lgdx.Graphics.FramesPerSecond) instead of DeltaTime.
I solved it by adding the following conditions in at the beginning of Sub LG_Render:

B4X:
'Step Setup      
        If lGdx.Graphics.DeltaTime > (1/60) AND lGdx.Graphics.DeltaTime <= (1/30) Then
            LGStep = lGdx.Graphics.DeltaTime
        Else If lGdx.Graphics.DeltaTime <= (1/60) Then
            LGStep = (1/60)
        Else If lGdx.Graphics.DeltaTime > (1/30) Then
            LGStep = (1/30)
        End If

LGStep is the variable I'm using to control the movement velocity on screen. This small piece of code keeps everything running smooth between 30 and 60 frames per second.

For more information about this Step Method, please refer to this post: https://www.b4x.com/android/forum/threads/how-to-make-games.32593/
Informatix said:
Mind the step

On a device, your application is not alone. There are services running, e.g. to check your mailbox regularly or to scan programs for viruses, and they can alter the flow of your game during short periods of time. You cannot do anything to prevent this, but you can adapt your game to these sudden changes by altering the time step. What’s this?

We saw in the previous chapter that you have only 16ms to do all your computations and render a scene. This span is not the time step. It’s just a timer interval and it will be impacted by a slowdown of your device. The time step is in fact a float value that defines the speed of your game. An example will be better than a long explanation:
Each time that you move an object in your game world, you increase or decrease its coordinates. If you do X = X + 2, two units are added whatever the elapsed time between two frames. If you introduce a time step, the formula becomes: X = X + (2 * TimeStep). With this time step, you can accelerate or decelerate your game at will, just by changing this value. Set it to the delta of time between two frames and your objects will move faster when the device is slowed. The player will see a constant move.
A real example:
Code:
Actor.X = Actor.X + Speed * lGdx.Graphics.DeltaTime
Speed is the speed property of the object to move and DeltaTime the time step. It is expressed in seconds between two frames. If everything goes well, its value should be close to 16/1000.

Sometimes the interval between two frames is very long (it’s the case when the antivirus of my phone checks the launched application) and the time step causes an issue called the tunnel effect. The step is so great that the move is really big, and your object can cross walls (it is moved directly on the other side). To avoid this, you should limit the value of your time step. Example:
Code:
DeltaTime = Min(lGdx.Graphics.DeltaTime, 0.05) 'max=50ms i.e. 20 fps
You cannot use a variable time step in all cases. Physics engines require a fixed time step. Box2D, for example, works very well with a value of 1/60. If it’s too slow for you, you can increase it up to 1/30, but don’t go over.

....
 

TheJinJ

Active Member
Licensed User
Longtime User
Sorry, confusion.
How to I set the joint definition to be a motor joint similar to
eg.
B4X:
RevoluteJointDef.Type = world.JOINTTYPE_RevoluteJoint
So the joint is created using
B4X:
Dim RevoluteJoint as lgBox2DRevoluteJoint = World.CreateJoint(RevoluteJointDef)
 
Last edited:

Informatix

Expert
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Longtime User
Sorry, confusion.
How to I set the joint definition to be a motor joint similar to
eg.
B4X:
RevoluteJointDef.Type = world.JOINTTYPE_RevoluteJoint
So the joint is created using
B4X:
Dim RevoluteJoint as lgBox2DRevoluteJoint = World.CreateJoint(RevoluteJointDef)
I see now where the type declaration is missing (lgWorld), but you don't need it in the above case. A RevoluteJoint has always the RevoluteJoint type.
 

TheJinJ

Active Member
Licensed User
Longtime User
I see now where the type declaration is missing (lgWorld), but you don't need it in the above case. A RevoluteJoint has always the RevoluteJoint type.

The motor joint type is missing, I used revolute as an example of the syntax, sorry for the confusion

This Motorjoint type is missing

B4X:
RevoluteJointDef.Type = world.JOINTTYPE_MotorJoint
 
Last edited:

TheJinJ

Active Member
Licensed User
Longtime User
I know you don't really have time to work on this library but noticed another possible fix required....

If a body has multiple fixtures the shape can be set ok but the position cannot. It always reports as the bodies centre.

eg
B4X:
Dim circleShape As lgBox2DCircleShape
....
circleShape.position.set(-2, -2)
fixtureDef.shape = circleShape
body.createFixture(fixtureDef)

No error is thrown when trying to set the position but if you retrieve it, it is always the 0, 0 so will be the body centre.

Any ideas?
 

Informatix

Expert
Licensed User
Longtime User
If a body has multiple fixtures the shape can be set ok but the position cannot. It always reports as the bodies centre.

eg
B4X:
Dim circleShape As lgBox2DCircleShape
....
circleShape.position.set(-2, -2)
fixtureDef.shape = circleShape
body.createFixture(fixtureDef)

No error is thrown when trying to set the position but if you retrieve it, it is always the 0, 0 so will be the body centre.

Any ideas?
This works:
circleShape.position = circleShape.position.set(-2, -2)
or:
Dim Position as lgMathVector2
Position.Set(-2, -2)
circleShape.position = Position
 

Crystal Noir

Member
Licensed User
Longtime User
Hi,

Are the example files are ok for the current version ? Beucause I tried to compile several but I can't launch any file, I have always a not found exception like this with the internal files.

Example for the particle file :

B4X:
LogCat connected to: 3204ddaf8d656111
--------- beginning of /dev/log/main


--------- beginning of /dev/log/system


Copying updated assets files (63)


** Activity (main) Create, isFirst = true **


** Activity (main) Resume **


sensor listener setup


OGL renderer: Mali-400 MP


OGL vendor: ARM
OGL version: OpenGL ES 2.0
OGL extensions: GL_EXT_debug_marker GL_OES_texture_npot GL_OES_compressed_ETC1_RGB8_texture GL_OES_standard_derivatives GL_OES_EGL_image GL_OES_depth24 GL_ARM_rgba8 GL_ARM_mali_shader_binary GL_OES_depth_texture GL_OES_packed_depth_stencil GL_EXT_texture_format_BGRA8888 GL_OES_vertex_half_float GL_EXT_blend_minmax GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_rgb8_rgba8 GL_EXT_multisampled_render_to_texture GL_EXT_discard_framebuffer GL_OES_get_program_binary GL_ARM_mali_program_binary GL_EXT_shader_texture_lod GL_EXT_robustness GL_OES_depth_texture_cube_map GL_KHR_debug


framebuffer: (5, 6, 5, 0)
depthbuffer: (24)
stencilbuffer: (8)
samples: (0)
coverage sampling: (false)
Managed meshes/app: { }
Managed textures/app: { }
Managed shaders/app: { }
Managed buffers/app: { }
Error occurred on line: 44 (main)
com.badlogic.gdx.utils.GdxRuntimeException: Error reading file: particles/particles.p (Internal)


    at com.badlogic.gdx.backends.android.AndroidFileHandle.read(SourceFile:76)
    at com.badlogic.gdx.graphics.g2d.ParticleEffect.loadEmitters(SourceFile:153)
    at com.badlogic.gdx.graphics.g2d.ParticleEffect.load(SourceFile:139)
    at anywheresoftware.b4a.libgdx.particles.lgParticleEffect.Load(SourceFile:151)
    at flm.b4a.libgdxtest.main._lg_create(main.java:398)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:636)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:302)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:238)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:121)
    at anywheresoftware.b4a.ShellBA$1.run(ShellBA.java:66)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5694)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.io.FileNotFoundException: particles/particles.p
    at android.content.res.AssetManager.openAsset(Native Method)
    at android.content.res.AssetManager.open(AssetManager.java:316)
    at android.content.res.AssetManager.open(AssetManager.java:290)
    at com.badlogic.gdx.backends.android.AndroidFileHandle.read(SourceFile:74)
    ... 22 more

Thx for helping me :)
 
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