Initial delay with black screen SurfaceView

[paulweinbmw]

Hey, I'm rendering a gltf file in a SurfaceView like in the examples. The rendering starts immediately I can see in the logs but the 3D object only becomes visible after a few seconds. Anyone knows if I need to invalidate, flush the buffers or something like that to get it working without delay?

`RenderedView(context: Context, attrs: AttributeSet) : SurfaceView(context, attrs), SurfaceHolder.Callback {

private lateinit var modelViewer: ModelViewer
private lateinit var choreographer: Choreographer
private lateinit var manipulator: Manipulator
private val automation = AutomationEngine()
private val viewerContent = AutomationEngine.ViewerContent()

init {
    println("## construct RenderedView")
    setZOrderOnTop(false)
    holder.setFormat(PixelFormat.UNKNOWN)
    holder.addCallback(this)
}

companion object {
    init {
        Utils.init()
    }
}

override fun surfaceCreated(holder: SurfaceHolder) {
    println("## surfaceCreated")
}

override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {
    println("## surfaceChanged")
}

override fun surfaceDestroyed(holder: SurfaceHolder) {
    println("## surfaceDestroyed")
}

fun onResume() {
    manipulator = Manipulator.Builder()
        .orbitHomePosition(0.0f, 0.15f, 1.0f)
        .targetPosition(0f, 0f, 0f)
        .viewport(width, height)
        .build(Manipulator.Mode.ORBIT)
    modelViewer = ModelViewer(this, manipulator = manipulator)
    viewerContent.view = modelViewer.view
    viewerContent.sunlight = modelViewer.light
    viewerContent.lightManager = modelViewer.engine.lightManager
    viewerContent.scene = modelViewer.scene
    viewerContent.renderer = modelViewer.renderer

    createDefaultRenderables()
    choreographer = Choreographer.getInstance()
    choreographer.postFrameCallback(frameCallback)
}

fun onPause() {
    choreographer.removeFrameCallback(frameCallback)
}

fun onDestroy() {
    choreographer.removeFrameCallback(frameCallback)
    modelViewer.engine.destroy()
}

private fun createDefaultRenderables() {
    val buffer = resources.assets.open("pucks/object.gltf").use { input ->
        val bytes = ByteArray(input.available())
        input.read(bytes)
        ByteBuffer.wrap(bytes)
    }

    modelViewer.loadModelGltf(buffer) { _ ->
        buffer
    }

    val json = StandardCharsets.UTF_8.decode(buffer).toString()
    viewerContent.assetLights = modelViewer.asset?.lightEntities
    automation.applySettings(modelViewer.engine, json, viewerContent)
    modelViewer.view.colorGrading = automation.getColorGrading(modelViewer.engine)
    modelViewer.cameraFocalLength = automation.viewerOptions.cameraFocalLength
    modelViewer.cameraNear = automation.viewerOptions.cameraNear
    modelViewer.cameraFar = automation.viewerOptions.cameraFar

    modelViewer.transformToUnitCube(Float3(0.0f, 0.0f, 0.0f))
    postInvalidate()
}

var rotation = 0L
var direction = 1

private val frameCallback = object : Choreographer.FrameCallback {
    override fun doFrame(currentTime: Long) {
        println("## doFrame")
        choreographer.postFrameCallback(this)
        modelViewer.render(currentTime)
        modelViewer.asset?.apply {
            modelViewer.transformToUnitCube(Float3(0.0f, -0.0f, 0.0f))
            val rootTransform = this.root.getTransform()
            val degrees = rotation.toFloat()
            if (rotation >= 90 || rotation <= -90) {
                direction *= -1 // Reverse direction when reaching boundaries
            }
            rotation += direction
            println("## currentTime: ${currentTime.toFloat()} degrees: $degrees")
            val yAxis = Float3(0f, 1f, 0f)
            this.root.setTransform(rootTransform * rotation(yAxis, degrees))
            postInvalidate()
        }
    }
}

private fun Int.getTransform(): Mat4 {
    val tm = modelViewer.engine.transformManager
    return Mat4.of(*tm.getTransform(tm.getInstance(this), FloatArray(16)))
}

private fun Int.setTransform(mat: Mat4) {
    val tm = modelViewer.engine.transformManager
    tm.setTransform(tm.getInstance(this), mat.toFloatArray())
}

[paulweinbmw]

@romainguy do you know maybe why my surfaceview stays black but the model is loaded 100% & the frameback is called already many times? But only after some seconds the object appears