asset and task for volume rendering

data/assets/examples/volume/generated/cartesiansequence.asset

@@ -35,4 +35,4 @@ local volume = {
 }
 
 local objects = { volume }
-assetHelper.registerSceneGraphNodes(asset, objects)
+assetHelper.registerSceneGraphNodes(asset, objects)

data/assets/scene/solarsystem/planets/earth/satellites/debris/volume/debris_volume.asset

@@ -0,0 +1,38 @@
+-- This asset requires OpenSpace to be built with the OPENSPACE_MODULE_VOLUME enabled
+
+-- Before using this asset,
+-- the volume data itself needs to be generated,
+-- using the task 'data/tasks/volume/debristasks/generate_debris_volume.task'
+
+local assetHelper = asset.require('util/asset_helper')
+local transforms = asset.require("scene/solarsystem/planets/earth/transforms")
+
+local earthRadius = 6.371E6
+
+local volume = {
+    Identifier = "DebrisVolume",
+    Parent = transforms.EarthBarycenter.Identifier,
+    Renderable = {
+        Type = "RenderableTimeVaryingVolume",
+        SourceDirectory = asset.localResource("generated"),
+        TransferFunction = asset.localResource("transferfunction.txt"),
+        StepSize = 0.01,
+        MinValue = 0,
+        MaxValue = 1,
+        GridType = "Cartesian",
+        SecondsBefore = 24*60*60, -- 50 years before
+        SecondsAfter = 24*60*60 -- 50 years after
+    },
+    GUI = {
+        Path = "/Volumes"
+    },
+    Transform = {
+        Scale = {
+            Type = "StaticScale",
+            Scale = earthRadius
+        }
+    }
+}
+
+local objects = { volume }
+assetHelper.registerSceneGraphNodes(asset, objects)

data/assets/scene/solarsystem/planets/earth/satellites/debris/volume/transferfunction.txt

@@ -0,0 +1,5 @@
+width 1024
+lower 0.0
+upper 1.0
+mappingkey 0.0 250 250 250  0
+mappingkey 1.0 200 200 200  255

data/tasks/volume/debristasks/generate_debris_volume.task

@@ -0,0 +1,20 @@
+local length = 60
+local tasks = {}
+
+for i=1,length do
+	local radius = 0.5 * (1 - i/length)
+	local step = string.format("%02d", i-1)
+	tasks[#tasks+1] = {
+	    Type = "GenerateRawVolumeTask", -- fix name
+        Input = input
+	    Dimensions = {32, 32, 32},
+	    LowerDomainBound = {-0.5, -0.5, -0.5},
+	    UpperDomainBound = {0.5, 0.5, 0.5},
+	    ValueFunction = fn,
+	    Time = "2018-05-04T00:00:" .. step,
+	    RawVolumeOutput = "${DATA}/assets/scene/solarsystem/planets/earth/satellites/debris/volume/generated/" .. step .. ".rawvolume",
+	    DictionaryOutput = "${DATA}/assets/scene/solarsystem/planets/earth/satellites/debris/volume/generated/" .. step .. ".dictionary"
+	}
+end
+
+return tasks