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Scenery LOD ideas for FlightGear: Difference between revisions
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Scenery LOD ideas for FlightGear (view source)
Revision as of 08:29, 19 February 2014
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== 02/2014 (F-JJTH) == | |||
'''F-JJTH:''' Looking at [http://forum.flightgear.org/viewtopic.php?f=5&t=22119 your topic about the framerate dropdown because of the new scenery] I would ask you to test the following patch: | |||
http://pastebin.com/p5HXirn5 | |||
<syntaxhighlight lang="diff"> | |||
diff --git a/simgear/scene/tgdb/obj.cxx b/simgear/scene/tgdb/obj.cxx | |||
index edb35f2..767c930 100644 | |||
--- a/simgear/scene/tgdb/obj.cxx | |||
+++ b/simgear/scene/tgdb/obj.cxx | |||
@@ -40,6 +40,7 @@ | |||
#include <osg/Referenced> | |||
#include <osg/StateSet> | |||
#include <osg/Switch> | |||
+#include <osgUtil/Simplifier> | |||
#include <boost/foreach.hpp> | |||
@@ -1213,6 +1214,25 @@ SGLoadBTG(const std::string& path, const simgear::SGReaderWriterOptions* options | |||
terrainGroup->setName("BTGTerrainGroup"); | |||
osg::Node* node = tileGeometryBin->getSurfaceGeometry(matlib); | |||
+ | |||
+ bool simplifierState = false; | |||
+ double ratio = 0.001; | |||
+ double maxLength = 1000.0; | |||
+ double maxError = 1000.0; | |||
+ if(options){ | |||
+ SGPropertyNode* propertyNode = options->getPropertyNode().get(); | |||
+ if (propertyNode) { | |||
+ simplifierState = propertyNode->getBoolValue("/sim/rendering/terrain/simplifier/enabled", simplifierState); | |||
+ ratio = propertyNode->getDoubleValue("/sim/rendering/terrain/simplifier/ratio", ratio); | |||
+ maxLength = propertyNode->getDoubleValue("/sim/rendering/terrain/simplifier/max-length", maxLength); | |||
+ maxError = propertyNode->getDoubleValue("/sim/rendering/terrain/simplifier/max-error", maxError); | |||
+ } | |||
+ } | |||
+ if(simplifierState) { | |||
+ osgUtil::Simplifier simplifier(ratio, maxError, maxLength); | |||
+ node->accept(simplifier); | |||
+ } | |||
+ | |||
if (node) | |||
terrainGroup->addChild(node); | |||
</syntaxhighlight> | |||
http://pastebin.com/zn0W31HV | |||
<syntaxhighlight lang="diff"> | |||
diff --git a/preferences.xml b/preferences.xml | |||
index da8416c..3b701c3 100644 | |||
--- a/preferences.xml | |||
+++ b/preferences.xml | |||
@@ -58,6 +58,14 @@ Started September 2000 by David Megginson, david@megginson.com | |||
<season type="string" preserve="y">summer</season> | |||
</startup> | |||
<rendering> | |||
+ <terrain> | |||
+ <simplifier> | |||
+ <enabled type="bool">false</enabled> | |||
+ <ratio type="double">0.001</ratio> | |||
+ <max-error type="double">1000.0</max-error> | |||
+ <max-length type="double">1000.0</max-length> | |||
+ </simplifier> | |||
+ </terrain> | |||
<materials-file>Materials/regions/materials.xml</materials-file> | |||
<rembrandt> | |||
<enabled type="bool">false</enabled> | |||
</syntaxhighlight> | |||
Then start FG with '''--prop:/sim/rendering/terrain/simplifier/enabled=true''' | |||
Every params take effect at run-time as soon as you reload the scenery after changing the value, but I've experimented a lot of value and the default values are fine. | |||
For information the expected result is to have less vertex: clement.delhamaide.free.fr/osg/ | |||
Of course less vertex = less detail... but I think it's more reasonable to give a "low-vertex-scenery" for those who don't have the requiered hardware. | |||
Also keep in mind that this patch has only a positive effect (at least I hope) on FPS, not on RAM (the whole BTG file is still loaded in RAM) | |||
Well, let me know if it improve the situation. | |||
The number of vertex should be definitely reduced. My screenshots (wireframe) are showing that osg::Simplifier works fine. | |||
But maybe the simplification is not enough important for seeing a positive effect. | |||
I will give a try tomorrow at KSFO, are you able to confirm me that enabling osg::Simplifier reduce the number of vertex (or not). A simple test is: | |||
* Start FG | |||
* Enable wireframe | |||
* Look at outdoor | |||
* Take a screenshot | |||
* Enable osg::Simplifier from property tree | |||
* Reload scenery | |||
* Take a screenshot | |||
Then compare the 2 screenshots and yo will immediately see if the effect is here | |||
'''Hooray:''' | |||
I have worked through quite a few OSG docs, and I think we can make this work - ideally, you would push your changes to gitorious, so that we can both work on them. I also asked poweroftwo (osgEarth) to have a look, because he's more familiar with the scenery/terrain and OSG side of things (also CC'ing Stuart and Zakalawe and the TG guys, so that they're aware of this). | |||
I would really love to see this implemented as a custom SimGear class, something like "LODManager" that is property-driven. | |||
We could then use it for 1) terrain, 2) main aircraft models (cockpit!) and 3) AI objects to expose a property-driven interface to customize LOD at runtime. | |||
The first thing that we could change is using SGPropertyChangeListener or property objects so that properties can be changed at runtime, without requiring a scenery-reload. | |||
I think we would only need to subclass osgUtil::Simplifier and make it derive from SGPropertyChangeListener, too - would that work ? | |||
<syntaxhighlight lang="cpp"> | |||
class SGLODManager : public osgUtil::Simplifier, SGPropertyChangeListener | |||
{ | |||
// implement the osgUtil::Simplifier & listener interfaces here | |||
}; | |||
</syntaxhighlight> | |||
The question is we can modify the visitor after it's been applied, or if that requires changes on the OSG side. | |||
It also seems that we can use some OSG machinery to simplify textures, too. | |||
= Ideas (2012) = | |||
Moving forum discussion to the wiki: | Moving forum discussion to the wiki: | ||
Maybe there could be one single globe texture, and each tile btg would have it's correct texture coordinates into that image. | Maybe there could be one single globe texture, and each tile btg would have it's correct texture coordinates into that image. | ||