In my application, I have scene objects that I would like to fade in and out, like a ghost. I am able to achieve this effect. (Note I am writing in Kotlin, so the syntax is slightly different.)
it.material.setColor("Diffuse", ColorRGBA(1f, 1f, 1f, 0.5f)) // TODO: Drive opacity via state
it.material.additionalRenderState.blendMode = RenderState.BlendMode.Alpha
it.queueBucket = RenderQueue.Bucket.Transparent
it.material.setBoolean("UseMaterialColors", true)
However, this makes objects appear darker. Here is what the scene looks like before the effect is applied:
And after (Ignore that some objects are still fully opaque—their material is being reset after I apply the effect, and it’s too cumbersome to refactor for the sake of this post):
This almost looks correct, but when the opacity is brought up to 100%, objects appear darker:
Upon further inspection, it seems as though setting UseMaterialColors to true causes those objects to ignore any lighting from an AmbientLight. When DirectionalLights are removed and only an AmbientLight is present in the scene, the effect is visible (again, some objects are having their material reset after the effect is applied):
So my question is: Why does setting UseMaterialColors to true cause objects to not be affected by an AmbientLight? And what is the fix?
I looked at [SOLVED] Lighting Issues or wrong understanding?, but I can’t discern what the solution is, other than the lighting color? Here’s how I apply the lights in my scene (Kotlin):
object LightingSetup {
fun setupLights(rootNode: Node): DirectionalLight {
val shadowsOnly = createDirectionalLight(rootNode, ColorRGBA.Black, Vector3f(0.1f, -1f, -0.1f))
createDirectionalLight(rootNode, ColorRGBA(0.9f, 0.9f, 0.9f, 1f), Vector3f(0f, -1f, -1f)) // Main light
createDirectionalLight(rootNode, ColorRGBA(0.1f, 0.1f, 0.3f, 1f), Vector3f(0f, 1f, 1f)) // Backlight
createAmbientLight(rootNode, ColorRGBA(0.5f, 0.5f, 0.5f, 1f)) // Ambience
return shadowsOnly // For a DirectionalLightShadowFilter
}
private fun createDirectionalLight(rootNode: Node, colorRGBA: ColorRGBA, direction: Vector3f): DirectionalLight {
return DirectionalLight().apply {
color = colorRGBA
this.direction = direction
rootNode.addLight(this)
}
}
private fun createAmbientLight(rootNode: Node, colorRGBA: ColorRGBA): AmbientLight {
return AmbientLight().apply {
color = colorRGBA
rootNode.addLight(this)
}
}
}
I apologize for my general lack of knowledge when it comes to these sorts of shading things—I appreciate any help!