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Attempt to explain what shadowsbin is doing

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This commit is contained in:
AnyOldName3 2020-10-31 19:06:20 +00:00
parent f7dddb8857
commit 449506fef1
2 changed files with 40 additions and 23 deletions
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44
components/sceneutil/shadowsbin.cpp
View File

@ -32,6 +32,7 @@ namespace
inline bool materialNeedShadows(osg::Material* m) inline bool materialNeedShadows(osg::Material* m)
{ {
// I'm pretty sure this needs to check the colour mode - vertex colours might override this value.
return m->getDiffuse(osg::Material::FRONT).a() > 0.5; return m->getDiffuse(osg::Material::FRONT).a() > 0.5;
} }
} }
@ -45,38 +46,45 @@ ShadowsBin::ShadowsBin()
mStateSet->addUniform(new osg::Uniform("useDiffuseMapForShadowAlpha", false)); mStateSet->addUniform(new osg::Uniform("useDiffuseMapForShadowAlpha", false));
} }
bool ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::unordered_set<StateGraph*>& uninteresting) bool ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::unordered_set<StateGraph*>& uninterestingCache)
{ {
std::vector<StateGraph*> return_path; std::vector<StateGraph*> return_path;
State state; State state;
StateGraph* sg_new = sg; StateGraph* sg_new = sg;
do do
{ {
if (uninteresting.find(sg_new) != uninteresting.end()) if (uninterestingCache.find(sg_new) != uninterestingCache.end())
break; break;
return_path.push_back(sg_new); return_path.push_back(sg_new);
sg_new = sg_new->_parent; sg_new = sg_new->_parent;
} while (sg_new && sg_new != root); } while (sg_new && sg_new != root);
for(std::vector<StateGraph*>::reverse_iterator itr=return_path.rbegin(); itr!=return_path.rend(); ++itr)
for(auto itr=return_path.rbegin(); itr!=return_path.rend(); ++itr)
{ {
const osg::StateSet* ss = (*itr)->getStateSet(); const osg::StateSet* ss = (*itr)->getStateSet();
if (!ss) continue; if (!ss)
continue;
accumulateModeState(ss, state.mAlphaBlend, state.mAlphaBlendOverride, GL_BLEND); accumulateModeState(ss, state.mAlphaBlend, state.mAlphaBlendOverride, GL_BLEND);
accumulateModeState(ss, state.mAlphaTest, state.mAlphaTestOverride, GL_ALPHA_TEST); accumulateModeState(ss, state.mAlphaTest, state.mAlphaTestOverride, GL_ALPHA_TEST);
const osg::StateSet::AttributeList& l = ss->getAttributeList();
osg::StateSet::AttributeList::const_iterator f = l.find(std::make_pair(osg::StateAttribute::MATERIAL, 0)); const osg::StateSet::AttributeList& attributes = ss->getAttributeList();
if (f != l.end()) osg::StateSet::AttributeList::const_iterator found = attributes.find(std::make_pair(osg::StateAttribute::MATERIAL, 0));
if (found != attributes.end())
{ {
const osg::StateSet::RefAttributePair* rap = &f->second; const osg::StateSet::RefAttributePair& rap = found->second;
accumulateState(state.mMaterial, static_cast<osg::Material*>(rap->first.get()), state.mMaterialOverride, rap->second); accumulateState(state.mMaterial, static_cast<osg::Material*>(rap.first.get()), state.mMaterialOverride, rap.second);
if (state.mMaterial && !materialNeedShadows(state.mMaterial)) if (state.mMaterial && !materialNeedShadows(state.mMaterial))
state.mMaterial = nullptr; state.mMaterial = nullptr;
} }
f = l.find(std::make_pair(osg::StateAttribute::FRONTFACE, 0));
if (f != l.end()) // osg::FrontFace specifies triangle winding, not front-face culling. We can't safely reparent anything under it.
found = attributes.find(std::make_pair(osg::StateAttribute::FRONTFACE, 0));
if (found != attributes.end())
state.mImportantState = true; state.mImportantState = true;
if ((*itr) != sg && !state.interesting()) if ((*itr) != sg && !state.interesting())
uninteresting.insert(*itr); uninterestingCache.insert(*itr);
} }
if (!state.needShadows()) if (!state.needShadows())
@ -103,6 +111,10 @@ bool ShadowsBin::State::needShadows() const
void ShadowsBin::sortImplementation() void ShadowsBin::sortImplementation()
{ {
// The cull visitor contains a stategraph.
// When a stateset is pushed, it's added/found as a child of the current stategraph node, then that node becomes the new current stategraph node.
// When a drawable is added, the current stategraph node is added to the current renderbin (if it's not there already) and the drawable is added as a renderleaf to the stategraph
// This means our list only contains stategraph nodes with directly-attached renderleaves, but they might have parents with more state set that needs to be considered.
if (!_stateGraphList.size()) if (!_stateGraphList.size())
return; return;
StateGraph* root = _stateGraphList[0]; StateGraph* root = _stateGraphList[0];
@ -117,12 +129,16 @@ void ShadowsBin::sortImplementation()
return; return;
} }
root = root->find_or_insert(mStateSet.get()); root = root->find_or_insert(mStateSet.get());
// root is now a stategraph with useDiffuseMapForShadowAlpha disabled but minimal other state
root->_leaves.reserve(_stateGraphList.size()); root->_leaves.reserve(_stateGraphList.size());
StateGraphList newList; StateGraphList newList;
std::unordered_set<StateGraph*> uninteresting; std::unordered_set<StateGraph*> uninterestingCache;
for (StateGraph* graph : _stateGraphList) for (StateGraph* graph : _stateGraphList)
{ {
if (!cullStateGraph(graph, root, uninteresting)) // Render leaves which shouldn't use the diffuse map for shadow alpha but do cast shadows become children of root, so graph is now empty. Don't add to newList.
// Graphs containing just render leaves which don't cast shadows are discarded. Don't add to newList.
// Graphs containing other leaves need to be in newList.
if (!cullStateGraph(graph, root, uninterestingCache))
newList.push_back(graph); newList.push_back(graph);
} }
if (!root->_leaves.empty()) if (!root->_leaves.empty())

19
components/sceneutil/shadowsbin.hpp
View File

@ -17,11 +17,11 @@ namespace SceneUtil
private: private:
osg::ref_ptr<osg::StateSet> mStateSet; osg::ref_ptr<osg::StateSet> mStateSet;
public: public:
META_Object(SceneUtil, ShadowsBin) META_Object(SceneUtil, ShadowsBin)
ShadowsBin(); ShadowsBin();
ShadowsBin(const ShadowsBin& rhs, const osg::CopyOp& copyop) : osgUtil::RenderBin(rhs, copyop), mStateSet(rhs.mStateSet) {} ShadowsBin(const ShadowsBin& rhs, const osg::CopyOp& copyop) : osgUtil::RenderBin(rhs, copyop), mStateSet(rhs.mStateSet) {}
virtual void sortImplementation(); virtual void sortImplementation();
struct State struct State
{ {
@ -35,16 +35,17 @@ namespace SceneUtil
bool mImportantState; bool mImportantState;
bool needTexture() const { return mAlphaBlend || mAlphaTest; } bool needTexture() const { return mAlphaBlend || mAlphaTest; }
bool needShadows() const; bool needShadows() const;
// A state is interesting if there's anything about it that might affect whether we can optimise child state
bool interesting() const { return !needShadows() || needTexture() || mAlphaBlendOverride || mAlphaTestOverride || mMaterialOverride || mImportantState; } bool interesting() const { return !needShadows() || needTexture() || mAlphaBlendOverride || mAlphaTestOverride || mMaterialOverride || mImportantState; }
}; };
bool cullStateGraph(osgUtil::StateGraph* sg, osgUtil::StateGraph* root, std::unordered_set<osgUtil::StateGraph*>& uninteresting); bool cullStateGraph(osgUtil::StateGraph* sg, osgUtil::StateGraph* root, std::unordered_set<osgUtil::StateGraph*>& uninteresting);
static void addPrototype(const std::string& name) static void addPrototype(const std::string& name)
{ {
osg::ref_ptr<osgUtil::RenderBin> bin (new ShadowsBin); osg::ref_ptr<osgUtil::RenderBin> bin (new ShadowsBin);
osgUtil::RenderBin::addRenderBinPrototype(name, bin); osgUtil::RenderBin::addRenderBinPrototype(name, bin);
} }
}; };
class ShadowsBinAdder class ShadowsBinAdder