B4A Library libGDX - Game Engine



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:
 
Last edited by a moderator:
Click to expand...

sterlingy

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Informatix,

I've been studying some Java code, but I'm still perplexed. Maybe you can decipher it.

I don't need to render the object as this code does. It's the casting that always throws me off. The code is something like this:

B4X: 
Private ShapeRenderer sr;
.
.
.

sr.setProjectionMatrix(camera.combined);
for (mapObject object:  map.getLayers().get("objects").getObjects)){

Polyline line = ((PolylineMapObject) Object).getPolyline();

sr.begin(ShapeType.line);
sr.polyline(line.getTransformedVertices());
sr.end();
}
 

sterlingy

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Informatix,

I should also mention that I get random null pointer exceptions, and they don't seem to be tied to anything in particular. Once I get the polyline issue resolved, I'll send the project to you. Maybe you can figure it out. The app will just crash, even when it isn't being manipulated.

-S
 

Informatix

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Here's an example to get the first object (a polyline) in the object layer named "myobjects":
B4X: 
Dim ObjectLayer As lgMapLayer
ObjectLayer = Maps.Layers.Get2("myobjects")
Dim myPolyObj As lgMapPolylineMapObject = ObjectLayer.Objects.Get(0)
Dim myPoly As lgMathPolyline = myPolyObj.Polyline
 

sterlingy

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Informatix,

I can read the Vertices and draw the Polyline as a ChainShape, but of course, the the Vertices are in an unscaled coordinate system. Any thoughts on applying a scale to all vertices?

I doubt I need to explain this, but when the TiledMap is rendered, I can supply a UnitScale, however, I can't figure out how to do the same with the Polyline, nor can I scale the ChainShape. The Polyline has both setScale and Scale methods, but they don't seem to do anything.

-SterlingY
 
Last edited:

sterlingy

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I'm trying to get a list of joints associated with a Box2D body, but for some reason, when I check the size, it always returns Zero, which destroys my If Then loop

The code is something like this:

B4X: 
    Dim heroBody As lgBox2DBody
    Dim currentJoints As lgArray
    currentJoints.Initialize
   
    heroBody = globals.numbersHeld.Get(0)
    heroBody.GetJointList(currentJoints)

currentJoints.size is always ZERO despite the fact that joints exist and are functioning as intended. I can manipulate heroBody in every other factor I have tried.

-S
 

Informatix

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I never used a polyline so I have no idea on the subject, except that I see in the code that you have to call getTransformedVertices if you changed the scale of your polyline.
 

Informatix

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Same problem for GetFixtureList. I'm going to fix that. Thanks for the report.
 

sterlingy

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Informatix said:
I never used a polyline so I have no idea on the subject, except that I see in the code that you have to call getTransformedVertices if you changed the scale of your polyline.
Click to expand...

Funny how I completely miss something. This problem is solved. Thanks. In regards to the getJointsList, I'm on hold until there is a solution. I can work on other aspects of the app, however.

-SterlingY
 
S

sorex

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@Informatix

I know you probably hate questions like this but...

I there a way to seperate things so that we don't need all the 3D, physics and other moders stuff
when we just want to create an 80 style retro games

I mean, 2Mb to move a sprite around the screen is slightly overkill
 

Informatix

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That's why I created the Lite version, but I agree that this version is still a big fat baby. I could reduce a lot more the JAR size but I don't want to maintain too much different versions of the library. And the choice is difficult to do among the things to remove (probably the network and the math stuff, maybe the stage classes...).
 

sterlingy

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New version! YAY!!

I'll be working with it over the next few days, but as I'll be travelling I'm not sure how much time I can give it. With the Joint List problem solved, however, I think I'll have a fully functioning app, minus graphics and level design. Fingers crossed.

-SterlingY
 
Reactions: JEG

walterf25

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Hi Frederick, thanks for the new version of libgdx, i recently started working on my next app after finishing up everything else i had going on, i must say i'm very excited to finally have time to dig into libgdx completely.
My app is based on the whack a mole game, so far i have the background set up and can make the moles pop up and detect the hits then they pop back down into their holes.
I wanted to switch the image of the mole when it gets hit to an image of a bleeding mole, but i came across a strange behavior on the textures when i try to implement that.
for example right now i have an image of justin beiber and when you tap him on the head i switch to another image of him but one where he is bruised and bleeding, the strange behavior is when i hide him back down, it switches to another different image, then the next time it switches to a completely different image, i'm not sure what's going on, i'm probably going crazy but i've already gone at least 20 times through my code and can't find where the mistake is.

this is the code where i set up the image on the texture in the LG_Create sub
B4X: 
    For i = 0 To 8
    moletexture(i).Initialize("assets/beiber.png")
    moletextureregion(i).InitializeWithTexture2(moletexture(i), 128, 128)
    Next

this is where the actor is initialized
B4X: 
    moleactor(0).Initialize("moleactor1")
    moleactor(0).setSize(18%x, 28.33%y)
    moleactor(0).setPosition(lGdx.Graphics.Width/2 - 8.165%x, 642 - (128 + 660))
    moleactor(0).ZIndex = 1

and when the actor is hit i switch the image to a different image here in the Molelistener_Click Event
B4X: 
Sub molelistener_Click(Event As lgScn2DInputEvent, X As Float, Y As Float)
moletexture(0).Initialize("assets/bleeding.png")
moletextureregion(0).InitializeWithTexture2(moletexture(0), 256, 256)
actorhit = True
End Sub

i'm including the apk file so you can see the issue i'm having, hopefully you'll be able to figure out what's going on.
https://dl.dropboxusercontent.com/u/82367588/Whack A Beiber.apk

Thanks for your hard work Frederick

Walter
 

Informatix

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walterf25 said:
for example right now i have an image of justin beiber
Click to expand...

It seems that you have a little sister....

Your snippets of code reveal two problems: one is with memory (you create eight times the same texture and do not dispose it when you re-initialize the instance) and another with programming: why do you load many times the same texture? You should load two textures, one with Beiber and his angel face, and one with a bruised face. Convert this texture to a drawable (Texture -> TextureRegion -> lgScn2DTextureRegionDrawable or Texture -> Sprite -> lgScn2DSpriteDrawable). Then create eight actors (lgScn2DImage class) that use one of these drawables depending on the context (cf. the drawable property).

And if the problem is still there after a proper rewriting, you should place a Log() everywhere to know what functions are called, what values are set, what parameters are passed, etc. (since you cannot use reliably the B4A debugger).

Hope that helps.

Note: I receive all forum messages in my mailbox so it is useless to send a private message to notify me. If I don't answer, there's a reason (I was too busy the past days and not always behind my computer).
 
Last edited:

sterlingy

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Informatix,

I've had time to work with v.93

So Get..List functions are working, but I'm not making much headway with doing anything with it. I'll explain what I'm trying to do: Imagine trying to create a train where each car is a BODY, and the connection between them is a JOINT, but periodically, I want to insert a new car between the first and second car. My thought was to get the JOINT from car1, and change it's BodyB to the car being inserted, then create a new JOINT to attach the inserted car to what is now the third car.

The problem is that I can get the list of associated joints, but I can only read, not write to the BodyA and BodyB properties.

As a temporary fix, I destroy the list of world's joints and then reconstruct the order of the bodies and associated joints. This is however sloppy and ultimately will not work for me, and it's a bit buggy.

On another topic, I looked at your Skater example, hoping the repeating background would have solved the repeating or swapping tiled maps, but I see it's a different beast. Any update on when you might be able to work on that?

About flipped sprites. Is it proper behavior that Sprite.Flip(x,y) flips every time you call it? For example every time you code Sprite.Flip(false, true) it performs a flip operation, as opposed to keeping it flipped from it's original state.

I started to clean up my code and make it better organized so I can scale it more efficiently, and I created a new Activity to handle loading of assets, the main menu and options, then make the gameplay a separate Activity. It occurred to me that this might be the wrong approach with libGDX. What are your thoughts?

Lastly, you may remember a problem we discussed a few months ago, where there were some anomalies when moving around a tiled map. I thought the problem was solved when the tileset didn't have a pixel gap between each tile. Seems like I'm wrong. I think you knew what caused it. Any hopes in it being resolved?

Cheers,

SterlingY

P.S. I haven't played with the Perspective Camera yet, but I think I need to get everything else through my head first.
 

sterlingy

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Some info on the inserting Bodies and Joints into a chain:

I rewrite my code, after I learned that it is not possible to change a Joint's BODY associations, once it has been created.

B4X: 
Public Sub Initialize(vBodyA As lgBox2DBody, vBodyB As lgBox2DBody)


    Dim heroBody As lgBox2DBody
    Dim connectionsList As lgArray
    connectionsList.Initialize
   
    heroBody = globals.numbersHeld.Get(0)
    heroBody.GetJointList(connectionsList)
   
    If globals.numbersHeld.Size = 1 Then
        globals.numbersHeld.Add(vBodyB)
    Else
        globals.numbersHeld.InsertAt(1, vBodyB)
    End If

    Log("numHeld:" & globals.numbersHeld.Size)
    Log("cJ: " & globals.connectionsList.Size)

    'Dim HeroJoint As lgBox2DRevoluteJoint
    If connectionsList.Size > 0 Then
    '    HeroJoint = connectionsList.Get(0)
        GamePlay.World.DestroyJoint(connectionsList.Get(0))
    End If

    Dim connectorJointDef As lgBox2DRevoluteJointDef
       
    If globals.numbersHeld.size = 2 Then
        connectorJointDef.bodyA = globals.numbersHeld.Get(0)   
        connectorJointDef.bodyB = globals.numbersHeld.Get(1)
       
        connectorJointDef.localAnchorA.Set(-5 , 0)
        connectorJointDef.localAnchorB.Set(2 , 0)
        connectorJointDef.collideConnected = False
       
        GamePlay.World.CreateJoint(connectorJointDef)
    Else
        connectorJointDef.bodyA = globals.numbersHeld.Get(1)   
        connectorJointDef.bodyB = globals.numbersHeld.Get(2)
       
        connectorJointDef.localAnchorA.Set(-2 , 0)
        connectorJointDef.localAnchorB.Set(2 , 0)
        connectorJointDef.collideConnected = False
       
        GamePlay.World.CreateJoint(connectorJointDef)
    End If

End Sub

I'm getting a class mismatch error on the following line: "
GamePlay.World.DestroyJoint(connectionsList.Get(0))"

It says that you can't cast a JointEdge to a Joint.

DestroyJoint wants an lgBox2DJoint, and my joints are RevoluteJoints.

-SterlingY
 

Informatix

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Hello,

I cannot fully help you before tomorrow evening because I have a lot of important things to do but here are quick answers to some of your questions: the pixel gap is due to roundings and the only solution that I know is to use the screen resolution for your tile renderer (no unit scale set); I didn't forget your demand for an endless scroll; Flip() flips the sprite every time; World.GetAllJoints returns a list of Joints but Body.GetJointList returns a list of JointEdges so, to remove the joint, you have to use myJointEdge.Joint.
 

sterlingy

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Thanks for checking in. I'll see what I can do in the meantime.

-SterlingY
 

walterf25

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Hi Frederick, thanks for the reply, in talking to Sterlingy about this same issue, he also suggested a couple of things, i've also implemented your suggestions of converting the texture to a drawable, and i'm not creating the same texture eight times as i was doing previous, i created a different class which takes care of creating the actors, however i did struggle a bit in placing the background actors and the main actors in the right zindex order, another issue i was having was when adding a clicklistener to the actors, for some reason only the last added actor was actually firing the change image code inside of it, it is now working, i had to change the click listener code to the main activity, i defined the click listener from the main activity and just passed it as a parameter to the creator actor sub in the createactors class, this is now working as i wanted. Thanks alot for your reply again Frederick, i understand that you only port this libraries but still i'am aware that this requires a lot of work and for that i'm greatful as this provides us with an opportunity to create better apps.

On another note, i've been trying to do some research about creating a camera shaking effect, for example when there's an explosion i've seen some really nice apps where the whole screen does this shaking effect, i noticed you posted the simplex noise library and that this is based on the perlin algorithm, i'm not sure if you have any input or experience on this, but would you know if the simplex noise library would be able to be used for something like that?

Thanks,
Walter
 
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