From 9141a8d8014a236eec3c2e557bf71731ef05deb8 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Tue, 24 Mar 2015 22:52:20 +0100
Subject: [PATCH] Fully implement NiStencilProperty (Feature #1057)

---
 apps/nifosgtest/test.cpp        |  3 ++
 components/nif/property.hpp     |  2 +-
 components/nifosg/nifloader.cpp | 53 +++++++++++++++++++++++++++------
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/apps/nifosgtest/test.cpp b/apps/nifosgtest/test.cpp
index 0da95d13d..253b5f99d 100644
--- a/apps/nifosgtest/test.cpp
+++ b/apps/nifosgtest/test.cpp
@@ -102,6 +102,9 @@ int main(int argc, char** argv)
 
     Nif::NIFFilePtr nif(new Nif::NIFFile(resourceMgr.get(argv[1]), std::string(argv[1])));
 
+    // For NiStencilProperty
+    osg::DisplaySettings::instance()->setMinimumNumStencilBits(8);
+
     osgViewer::Viewer viewer;
 
     osg::ref_ptr<osg::Group> root(new osg::Group());
diff --git a/components/nif/property.hpp b/components/nif/property.hpp
index 2633b16c5..96156c6d8 100644
--- a/components/nif/property.hpp
+++ b/components/nif/property.hpp
@@ -221,7 +221,7 @@ struct S_StencilProperty
         4   TEST_GREATER
         5   TEST_NOT_EQUAL
         6   TEST_GREATER_EQUAL
-        7   TEST_ALWAYS
+        7   TEST_NEVER (though nifskope comment says TEST_ALWAYS, but ingame it is TEST_NEVER)
      */
     int compareFunc;
     unsigned stencilRef;
diff --git a/components/nifosg/nifloader.cpp b/components/nifosg/nifloader.cpp
index 2ed91d467..45619b21b 100644
--- a/components/nifosg/nifloader.cpp
+++ b/components/nifosg/nifloader.cpp
@@ -116,6 +116,40 @@ namespace
         }
     }
 
+    osg::Stencil::Function getStencilFunction(int func)
+    {
+        switch (func)
+        {
+        case 0: return osg::Stencil::NEVER;
+        case 1: return osg::Stencil::LESS;
+        case 2: return osg::Stencil::EQUAL;
+        case 3: return osg::Stencil::LEQUAL;
+        case 4: return osg::Stencil::GREATER;
+        case 5: return osg::Stencil::NOTEQUAL;
+        case 6: return osg::Stencil::GEQUAL;
+        case 7: return osg::Stencil::NEVER; // NifSkope says this is GL_ALWAYS, but in MW it's GL_NEVER
+        default:
+            std::cerr << "Unexpected stencil function: " << func << std::endl;
+            return osg::Stencil::NEVER;
+        }
+    }
+
+    osg::Stencil::Operation getStencilOperation(int op)
+    {
+        switch (op)
+        {
+        case 0: return osg::Stencil::KEEP;
+        case 1: return osg::Stencil::ZERO;
+        case 2: return osg::Stencil::REPLACE;
+        case 3: return osg::Stencil::INCR;
+        case 4: return osg::Stencil::DECR;
+        case 5: return osg::Stencil::INVERT;
+        default:
+            std::cerr << "Unexpected stencil operation: " << op << std::endl;
+            return osg::Stencil::KEEP;
+        }
+    }
+
     // Collect all properties affecting the given node that should be applied to an osg::Material.
     void collectMaterialProperties(const Nif::Node* nifNode, std::vector<const Nif::Property*>& out)
     {
@@ -1095,16 +1129,17 @@ namespace NifOsg
                 stateset->setMode(GL_CULL_FACE, stencilprop->data.drawMode == 3 ? osg::StateAttribute::OFF
                                                                                 : osg::StateAttribute::ON);
 
-                // TODO:
-                // Stencil settings not enabled yet, not sure if the original engine is actually using them,
-                // since they might conflict with Morrowind's stencil shadows.
-                /*
-                osg::Stencil* stencil = new osg::Stencil;
-                stencil->setFunction(func, stencilprop->data.stencilRef, stencilprop->data.stencilMask);
+                if (stencilprop->data.enabled != 0)
+                {
+                    osg::Stencil* stencil = new osg::Stencil;
+                    stencil->setFunction(getStencilFunction(stencilprop->data.compareFunc), stencilprop->data.stencilRef, stencilprop->data.stencilMask);
+                    stencil->setStencilFailOperation(getStencilOperation(stencilprop->data.failAction));
+                    stencil->setStencilPassAndDepthFailOperation(getStencilOperation(stencilprop->data.zFailAction));
+                    stencil->setStencilPassAndDepthPassOperation(getStencilOperation(stencilprop->data.zPassAction));
 
-                stateset->setMode(GL_STENCIL_TEST, stencilprop->data.enabled != 0 ? osg::StateAttribute::ON
-                                                                                  : osg::StateAttribute::OFF);
-                */
+                    stateset->setAttributeAndModes(stencil, osg::StateAttribute::ON);
+                }
+                break;
             }
             case Nif::RC_NiWireframeProperty:
             {