I'm just trying to get a basic box rendered with LibGDX (using Kotlin & LibKTX) but am running into some issues.
If I call the ModelBuilder createBox
function without the specified begin()
and end()
functions my box is not rendered. I checked the materials, camera position, the bounding box, added a light source, etc. but it's just.. not there. I figured the issue was with the way I was building the nodes, as I can't find an issue with the Material.
This is how I am trying to render my box:
class HomeView(private val baseUI: BaseUI) : KtxScreen {
private val cam by lazy { PerspectiveCamera(67f, baseUI.aWidth, baseUI.aHeight) }
private val boxInstance: ModelInstance
private val modelBatch: ModelBatch
private val modelBuilder: ModelBuilder by lazy { ModelBuilder() }
private val vertexAttributes =
VertexAttributes.Usage.Position.toLong() or
VertexAttributes.Usage.Normal.toLong() or
VertexAttributes.Usage.TextureCoordinates.toLong()
private val greenMat by lazy { Material(ColorAttribute.createDiffuse(Color.GREEN)) }
private val environment by lazy { Environment() }
//------ end global
init {
cam.position.set(vec3(-10f, -10f, 10f))
cam.lookAt(0f, 0f, 0f)
cam.near = .1f
cam.far = 10f
cam.update()
modelBatch = ModelBatch()
modelBuilder.begin()
modelBuilder.createBox(5f, 5f, 5f, greenMat, vertexAttributes)
boxInstance = ModelInstance(modelBuilder.end())
environment.set(ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f))
environment.add(DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f))
}
override fun render(delta: Float) {
Gdx.gl.glViewport(0, 0, baseUI.aWidth.toInt(), baseUI.aHeight.toInt())
//this is working, screen appears grey
clearScreen(.3f, .3f, .3f, 1f)
modelBatch.begin(cam)
modelBatch.render(boxInstance, environment)
modelBatch.end()
}
//rest omitted
}
and here is my BaseUI class that I'm using to add the screen (I'm just trying to test screens out, this is all just for testing purposes so ignore the inefficiency please)
class BaseUI : KtxGame<KtxScreen>(), KtxApplicationAdapter {
val aWidth by lazy { Gdx.graphics.width.toFloat() }
val aHeight by lazy { Gdx.graphics.height.toFloat() }
override fun create() {
addScreen(HomeView(this))
setScreen<HomeView>()
}
override fun render() {
super<KtxGame>.render()
}
//rest ommitted
}
When I run this I get the following error:
Exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: Call end() first
which makes it seem like I need to call modelBatch.end()
before I even create the nodes, which is confusing. I feel like I am doing something very basic wrong here, as I was able to get the basic 3D examples working back when I was trying this with Java a few years back.
So, two questions:
- Why is LibGDX saying that I need to call
end()
before I create the nodes withModelBuilder
? - Is using
modelBuilder.begin()
andmodelBuilder.end()
actually the best way to use the ModelBuilder? I've yet to see a 3D example do this. Admittedly, all the 3D examples I have found have been from like 2013 so this might just be something that's been added. The LibGDX 3D section says to use this set of tutorials that do not use thebegin()
andend()
functions, so I'm a bit confused as to what is the "best practice".
Thanks for any help!
edit: I tried it with a loaded model and it's having the same issue. Hmm..
edit2: Thank you Xoppa for helping me figure out what was wrong. The LibKTX specific function clearScreen()
did not incorporate the GL20.GL_COLOR_BUFFER_BIT
clear function as expected, which was my bad from reading their documentation. Adding this to my render function displayed the green box as expected:
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT or GL20.GL_DEPTH_BUFFER_BIT)