Add the ability to load images lazily for RenderablePlanes

Add ability to purge textures from RAM if they are read-only
Make use of both for constellation images to reduce the memory footprint

(cherry picked from commit 7f0c92430f)

data/assets/scene/milkyway/constellations/constellation_art.asset

@@ -1,11 +1,102 @@
-local constellation_helper = asset.require('./generate_constellations')
-
 local constellationsCSV = asset.localResource('constellation_data.csv')
+local transforms = asset.require("scene/solarsystem/sun/transforms")
+
+local images = asset.syncedResource({
+    Name = "Constellation Images",
+    Type = "HttpSynchronization",
+    Identifier = "constellation_images",
+    Version = 1
+})
+
+-- local image_resolution = "low"
+-- local image_resolution = "medium"
+local image_resolution = "high"
+
+--function that reads the file
+local createConstellations = function (guiPath, constellationfile)
+  local genConstellations = {};
+  --skip the first line
+  local notFirstLine = false;
+  -- define parsec to meters
+  local PARSEC_CONSTANT = 3.0856776E16;
+  -- how many parsecs away do you want the images to be?
+  -- this setting puts the billboards at the location of the constellation bounds grid from DU.
+  -- but they can really be anywhere since the billboard size will scale with distance.
+  local distanceMultiplier = 3.2;
+  local baseScale = 1e17;
+  for line in io.lines(openspace.absPath(constellationfile)) do
+      if (notFirstLine) then
+        -- describes the data
+        local matchstring = '(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-)$'
+        local group, abbreviation, name, x, y, z, scale, imageName, rotX, rotY, rotZ, centerStar = line:match(matchstring)
+        local magVec = math.sqrt(x*x + y*y + z*z)
+        local normx = x/magVec
+        local normy = y/magVec
+        local normz = z/magVec
+
+        group = (group == '' and globe or group)
+
+        local texture
+        if image_resolution == "low" then
+          texture = images .. "/" .. imageName:sub(1, -5) .. "-512.png"
+        elseif image_resolution == "medium" then
+          texture = images .. "/" .. imageName:sub(1, -5) .. "-1024.png"
+        elseif image_resolution == "high" then
+          texture = images .. "/" .. imageName
+        else
+          openspace.printError("Unknown image resolution: " .. image_resolution)
+        end
+
+        local aconstellation = {
+          Identifier = guiPath .. '-' .. name,
+          Parent = transforms.SolarSystemBarycenter.Identifier,
+          Transform = {
+              Translation = {
+                  Type = "StaticTranslation",
+                  -- position is in parsecs from the SolarSystemBarycenter, so convert to meters
+                  Position = {
+                    normx * PARSEC_CONSTANT * distanceMultiplier,
+                    normy * PARSEC_CONSTANT * distanceMultiplier,
+                    normz * PARSEC_CONSTANT * distanceMultiplier
+                  }
+              },
+              Rotation = {
+                  Type = "StaticRotation",
+                  Rotation = { tonumber(rotX), tonumber(rotY), tonumber(rotZ) }
+              }
+
+          },
+          Renderable = {
+              Type = "RenderablePlaneImageLocal",
+              Size = tonumber(baseScale * scale * distanceMultiplier / 10),
+              Enabled = false,
+              Origin = "Center",
+              Billboard = false,
+              LazyLoading = true,
+              Texture = texture,
+              BlendMode = "Additive",
+              Opacity = 0.1
+          },
+          Tag = { "ConstellationArtImage", group },
+          GUI = {
+              Name = name .. ' Image',
+              Path = '/Milky Way/' .. guiPath
+          }
+        }
+        table.insert(genConstellations, aconstellation);
+
+      else
+        notFirstLine = true
+      end
+  end
+  return genConstellations
+end
+
 
 local nodes = {}
 
 asset.onInitialize(function ()
-  nodes = constellation_helper.createConstellations('Constellation Art', constellationsCSV)
+  nodes = createConstellations('Constellation Art', constellationsCSV)
   for _, n in ipairs(nodes) do
     openspace.addSceneGraphNode(n);
   end

data/assets/scene/milkyway/constellations/generate_constellations.asset

@@ -1,79 +0,0 @@
-local assetHelper = asset.require('util/asset_helper')
-local transforms = asset.require("scene/solarsystem/sun/transforms")
-
-local images = asset.syncedResource({
-    Name = "Constellation Images",
-    Type = "HttpSynchronization",
-    Identifier = "constellation_images",
-    Version = 1
-})
-
---function that reads the file
-local createConstellations = function (guiPath, constellationfile)
-  local genConstellations = {};
-  --skip the first line
-  local notFirstLine = false;
-  -- define parsec to meters
-  local PARSEC_CONSTANT = 3.0856776E16;
-  -- how many parsecs away do you want the images to be?
-  -- this setting puts the billboards at the location of the constellation bounds grid from DU.
-  -- but they can really be anywhere since the billboard size will scale with distance.
-  local distanceMultiplier = 3.2;
-  local baseScale = 1e17;
-  for line in io.lines(openspace.absPath(constellationfile)) do
-      if (notFirstLine) then
-        -- describes the data
-        local matchstring = '(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-)$'
-        local group, abbreviation, name, x, y, z, scale, imageName, rotX, rotY, rotZ, centerStar = line:match(matchstring)
-        local magVec = math.sqrt(x*x + y*y + z*z)
-        local normx = x/magVec
-        local normy = y/magVec
-        local normz = z/magVec
-
-        group = (group == '' and globe or group)
-
-        local aconstellation = {
-          Identifier = guiPath .. '-' .. name,
-          Parent = transforms.SolarSystemBarycenter.Identifier,
-          Transform = {
-              Translation = {
-                  Type = "StaticTranslation",
-                  -- position is in parsecs from the SolarSystemBarycenter, so convert to meters
-                  Position = {
-                    normx * PARSEC_CONSTANT * distanceMultiplier,
-                    normy * PARSEC_CONSTANT * distanceMultiplier,
-                    normz * PARSEC_CONSTANT * distanceMultiplier
-                  }
-              },
-              Rotation = {
-                  Type = "StaticRotation",
-                  Rotation = { tonumber(rotX), tonumber(rotY), tonumber(rotZ) }
-              }
-
-          },
-          Renderable = {
-              Type = "RenderablePlaneImageLocal",
-              Size = tonumber(baseScale*scale*distanceMultiplier/10),
-              Enabled = false,
-              Origin = "Center",
-              Billboard = false,
-              Texture = images .. "/" .. imageName,
-              BlendMode = "Additive",
-              Opacity = 0.1
-          },
-          Tag = { "ConstellationArtImage", group },
-          GUI = {
-              Name = name .. ' Image',
-              Path = '/Milky Way/' .. guiPath
-          }
-        }
-        table.insert(genConstellations, aconstellation);
-
-      else
-        notFirstLine = true
-      end
-  end
-  return genConstellations
-end
-
-asset.export('createConstellations', createConstellations)

modules/base/rendering/renderableplaneimagelocal.cpp

@@ -36,6 +36,8 @@
 #include <fstream>
 
 namespace {
+    constexpr const char* KeyLazyLoading = "LazyLoading";
+
     constexpr openspace::properties::Property::PropertyInfo TextureInfo = {
         "Texture",
         "Texture",
@@ -70,6 +72,15 @@ documentation::Documentation RenderablePlaneImageLocal::Documentation() {
                 new StringVerifier,
                 Optional::Yes,
                 RenderableTypeInfo.description
+            },
+            {
+                KeyLazyLoading,
+                new BoolVerifier,
+                Optional::Yes,
+                "If this value is set to 'true', the image for this plane will not be "
+                "loaded at startup but rather when image is shown for the first time. "
+                "Additionally, if the plane is hidden, the image will automatically be "
+                "unloaded"
             }
         }
     };
@@ -116,16 +127,34 @@ RenderablePlaneImageLocal::RenderablePlaneImageLocal(const ghoul::Dictionary& di
     else {
         setRenderBin(Renderable::RenderBin::Opaque);
     }
+
+    if (dictionary.hasKey(KeyLazyLoading)) {
+        _isLoadingLazily = dictionary.value<bool>(KeyLazyLoading);
+
+        if (_isLoadingLazily) {
+            _enabled.onChange([this]() {
+                if (!_enabled) {
+                    BaseModule::TextureManager.release(_texture);
+                    _texture = nullptr;
+                }
+                if (_enabled) {
+                    _textureIsDirty = true;
+                }
+            });
+        }
+    }
 }
 
 bool RenderablePlaneImageLocal::isReady() const {
-    return RenderablePlane::isReady() && (_texture != nullptr);
+    return RenderablePlane::isReady();
 }
 
 void RenderablePlaneImageLocal::initializeGL() {
     RenderablePlane::initializeGL();
 
-    loadTexture();
+    if (!_isLoadingLazily) {
+        loadTexture();
+    }
 }
 
 void RenderablePlaneImageLocal::deinitializeGL() {
@@ -165,8 +194,8 @@ void RenderablePlaneImageLocal::loadTexture() {
                     fmt::format("Loaded texture from '{}'", absPath(path))
                 );
                 texture->uploadTexture();
-
                 texture->setFilter(ghoul::opengl::Texture::FilterMode::LinearMipMap);
+                texture->purgeFromRAM();
 
                 return texture;
             }

modules/base/rendering/renderableplaneimagelocal.h

@@ -60,6 +60,7 @@ private:
     ghoul::opengl::Texture* _texture = nullptr;
     std::unique_ptr<ghoul::filesystem::File> _textureFile;
 
+    bool _isLoadingLazily = false;
     bool _textureIsDirty = false;
 };
 

modules/base/rendering/renderableplaneimageonline.cpp

@@ -133,10 +133,8 @@ void RenderablePlaneImageOnline::update(const UpdateData&) {
                 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 
                 texture->uploadTexture();
-
-                // Textures of planets looks much smoother with AnisotropicMipMap rather
-                // than linear
                 texture->setFilter(ghoul::opengl::Texture::FilterMode::LinearMipMap);
+                texture->purgeFromRAM();
 
                 _texture = std::move(texture);
                 _textureIsDirty = false;