Don't keep the majority of textures in RAM if they are not needed, further reducing the memory footprint

modules/base/rendering/renderablemodel.cpp

@@ -453,6 +453,7 @@ void RenderableModel::loadTexture() {
             );
             _texture->uploadTexture();
             _texture->setFilter(ghoul::opengl::Texture::FilterMode::AnisotropicMipMap);
+            _texture->purgeFromRAM();
         }
     }
 }

modules/base/rendering/renderablesphere.cpp

@@ -488,6 +488,7 @@ void RenderableSphere::loadTexture() {
             );
             texture->uploadTexture();
             texture->setFilter(ghoul::opengl::Texture::FilterMode::LinearMipMap);
+            texture->purgeFromRAM();
             _texture = std::move(texture);
         }
     }

modules/base/rendering/screenspaceframebuffer.cpp

@@ -180,6 +180,7 @@ void ScreenSpaceFramebuffer::createFramebuffer() {
 
     _texture->uploadTexture();
     _texture->setFilter(ghoul::opengl::Texture::FilterMode::LinearMipMap);
+    _texture->purgeFromRAM();
     _framebuffer->attachTexture(_texture.get(), GL_COLOR_ATTACHMENT0);
     _framebuffer->deactivate();
 }

modules/base/rendering/screenspaceimagelocal.cpp

@@ -132,10 +132,8 @@ void ScreenSpaceImageLocal::update() {
             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);
             _objectSize = _texture->dimensions();

modules/base/rendering/screenspaceimageonline.cpp

@@ -142,10 +142,8 @@ void ScreenSpaceImageOnline::update() {
                 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);
                 _objectSize = _texture->dimensions();