Fix light

demo/playground/src/jvmMain/kotlin/gdmlCubes.kt

@@ -1,13 +1,20 @@
 package space.kscience.visionforge.examples
 
 import space.kscience.gdml.GdmlShowCase
+import space.kscience.visionforge.Colors
 import space.kscience.visionforge.gdml.toVision
 import space.kscience.visionforge.html.ResourceLocation
 import space.kscience.visionforge.solid.Solids
+import space.kscience.visionforge.solid.ambientLight
+import space.kscience.visionforge.solid.set
 
 fun main() = makeVisionFile(resourceLocation = ResourceLocation.SYSTEM) {
     vision("canvas") {
         requirePlugin(Solids)
-        GdmlShowCase.cubes().toVision()
+        GdmlShowCase.cubes().toVision().also {
+            it.ambientLight {
+                color.set(Colors.white)
+            }
+        }
     }
 }

demo/sat-demo/src/main/kotlin/ru/mipt/npm/sat/satServer.kt

@@ -8,6 +8,7 @@ import space.kscience.dataforge.context.Context
 import space.kscience.dataforge.context.fetch
 import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.names.Name
+import space.kscience.visionforge.Colors
 import space.kscience.visionforge.html.Page
 import space.kscience.visionforge.html.plus
 import space.kscience.visionforge.server.close
@@ -28,7 +29,11 @@ fun main() {
     val solids = satContext.fetch(Solids)
 
     //Create a geometry
-    val sat = solids.visionOfSatellite(ySegments = 3)
+    val sat = solids.visionOfSatellite(ySegments = 3).apply {
+        ambientLight {
+            color.set(Colors.white)
+        }
+    }
 
     val server = satContext.visionManager.serve {
         page(header = Page.threeJsHeader + Page.styleSheetHeader("css/styles.css")) {

visionforge-core/src/commonMain/kotlin/space/kscience/visionforge/VisionChange.kt

@@ -9,6 +9,7 @@ import kotlinx.serialization.Serializable
 import space.kscience.dataforge.meta.*
 import space.kscience.dataforge.meta.descriptors.MetaDescriptor
 import space.kscience.dataforge.names.Name
+import space.kscience.dataforge.names.isEmpty
 import space.kscience.dataforge.names.plus
 import kotlin.jvm.Synchronized
 import kotlin.time.Duration
@@ -49,7 +50,7 @@ public object NullVision : Vision {
 public class VisionChangeBuilder(private val manager: VisionManager) : MutableVisionContainer<Vision> {
 
     private var vision: Vision? = null
-    private val propertyChange = MutableMeta()
+    private var propertyChange = MutableMeta()
     private val children: HashMap<Name, VisionChangeBuilder> = HashMap()
 
     public fun isEmpty(): Boolean = propertyChange.isEmpty() && propertyChange.isEmpty() && children.isEmpty()
@@ -61,7 +62,11 @@ public class VisionChangeBuilder(private val manager: VisionManager) : MutableVi
     public fun propertyChanged(visionName: Name, propertyName: Name, item: Meta?) {
         if (visionName == Name.EMPTY) {
             //Write property removal as [Null]
+            if (propertyName.isEmpty()) {
+                propertyChange = item?.toMutableMeta() ?: MutableMeta()
+            } else {
                 propertyChange[propertyName] = (item ?: Meta(Null))
+            }
         } else {
             getOrPutChild(visionName).propertyChanged(Name.EMPTY, propertyName, item)
         }