Replace deprecated alpha test in shader visitor

components/CMakeLists.txt

@@ -46,7 +46,7 @@ add_component_dir (resource
     )
 
 add_component_dir (shader
-    shadermanager shadervisitor
+    shadermanager shadervisitor removedalphafunc
     )
 
 add_component_dir (sceneutil

components/sceneutil/mwshadowtechnique.cpp

@@ -278,7 +278,7 @@ void VDSMCameraCullCallback::operator()(osg::Node* node, osg::NodeVisitor* nv)
     static osg::ref_ptr<osg::StateSet> ss;
     if (!ss)
     {
-        ShadowsBinAdder adder("ShadowsBin");
+        ShadowsBinAdder adder("ShadowsBin", _vdsm->getCastingPrograms());
         ss = new osg::StateSet;
         ss->setRenderBinDetails(osg::StateSet::OPAQUE_BIN, "ShadowsBin", osg::StateSet::OVERRIDE_PROTECTED_RENDERBIN_DETAILS);
     }
@@ -883,10 +883,14 @@ void SceneUtil::MWShadowTechnique::setupCastingShader(Shader::ShaderManager & sh
 {
     // This can't be part of the constructor as OSG mandates that there be a trivial constructor available
 
-    _castingProgram = new osg::Program();
+    osg::ref_ptr<osg::Shader> castingVertexShader = shaderManager.getShader("shadowcasting_vertex.glsl", {}, osg::Shader::VERTEX);
-
+    for (int alphaFunc = GL_NEVER; alphaFunc <= GL_ALWAYS; ++alphaFunc)
-    _castingProgram->addShader(shaderManager.getShader("shadowcasting_vertex.glsl", Shader::ShaderManager::DefineMap(), osg::Shader::VERTEX));
+    {
-    _castingProgram->addShader(shaderManager.getShader("shadowcasting_fragment.glsl", Shader::ShaderManager::DefineMap(), osg::Shader::FRAGMENT));
+        auto& program = _castingPrograms[alphaFunc - GL_NEVER];
+        program = new osg::Program();
+        program->addShader(castingVertexShader);
+        program->addShader(shaderManager.getShader("shadowcasting_fragment.glsl", { {"alphaFunc", std::to_string(alphaFunc)} }, osg::Shader::FRAGMENT));
+    }
 }
 
 MWShadowTechnique::ViewDependentData* MWShadowTechnique::createViewDependentData(osgUtil::CullVisitor* /*cv*/)
@@ -1604,10 +1608,11 @@ void MWShadowTechnique::createShaders()
 
     }
 
-    if (!_castingProgram)
+    if (!_castingPrograms[GL_ALWAYS - GL_NEVER])
         OSG_NOTICE << "Shadow casting shader has not been set up. Remember to call setupCastingShader(Shader::ShaderManager &)" << std::endl;
 
-    _shadowCastingStateSet->setAttributeAndModes(_castingProgram, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
+    // Always use the GL_ALWAYS shader as the shadows bin will change it if necessary
+    _shadowCastingStateSet->setAttributeAndModes(_castingPrograms[GL_ALWAYS - GL_NEVER], osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
     // The casting program uses a sampler, so to avoid undefined behaviour, we must bind a dummy texture in case no other is supplied
     _shadowCastingStateSet->setTextureAttributeAndModes(0, _fallbackBaseTexture.get(), osg::StateAttribute::ON);
     _shadowCastingStateSet->addUniform(new osg::Uniform("useDiffuseMapForShadowAlpha", true));

components/sceneutil/mwshadowtechnique.hpp

@@ -215,6 +215,8 @@ namespace SceneUtil {
 
         virtual void createShaders();
 
+        virtual std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER> getCastingPrograms() const { return _castingPrograms; }
+
         virtual bool selectActiveLights(osgUtil::CullVisitor* cv, ViewDependentData* vdd) const;
 
         virtual osg::Polytope computeLightViewFrustumPolytope(Frustum& frustum, LightData& positionedLight);
@@ -288,7 +290,7 @@ namespace SceneUtil {
         };
 
         osg::ref_ptr<DebugHUD>                  _debugHud;
-        osg::ref_ptr<osg::Program>              _castingProgram;
+        std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER> _castingPrograms;
     };
 
 }

components/sceneutil/shadowsbin.cpp

@@ -1,7 +1,9 @@
 #include "shadowsbin.hpp"
 #include <unordered_set>
 #include <osg/StateSet>
+#include <osg/AlphaFunc>
 #include <osg/Material>
+#include <osg/Program>
 #include <osgUtil/StateGraph>
 
 using namespace osgUtil;
@@ -40,6 +42,10 @@ namespace
 namespace SceneUtil
 {
 
+std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER> ShadowsBin::sCastingPrograms = {
+    nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr
+};
+
 ShadowsBin::ShadowsBin()
 {
     mNoTestStateSet = new osg::StateSet;
@@ -49,6 +55,12 @@ ShadowsBin::ShadowsBin()
     mShaderAlphaTestStateSet = new osg::StateSet;
     mShaderAlphaTestStateSet->addUniform(new osg::Uniform("alphaTestShadows", true));
     mShaderAlphaTestStateSet->setMode(GL_BLEND, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);
+
+    for (size_t i = 0; i < sCastingPrograms.size(); ++i)
+    {
+        mAlphaFuncShaders[i] = new osg::StateSet;
+        mAlphaFuncShaders[i]->setAttribute(sCastingPrograms[i], osg::StateAttribute::ON | osg::StateAttribute::PROTECTED | osg::StateAttribute::OVERRIDE);
+    }
 }
 
 StateGraph* ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::unordered_set<StateGraph*>& uninterestingCache)
@@ -71,7 +83,6 @@ StateGraph* ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::un
             continue;
 
         accumulateModeState(ss, state.mAlphaBlend, state.mAlphaBlendOverride, GL_BLEND);
-        accumulateModeState(ss, state.mAlphaTest, state.mAlphaTestOverride, GL_ALPHA_TEST);
 
         const osg::StateSet::AttributeList& attributes = ss->getAttributeList();
         osg::StateSet::AttributeList::const_iterator found = attributes.find(std::make_pair(osg::StateAttribute::MATERIAL, 0));
@@ -83,6 +94,14 @@ StateGraph* ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::un
                 state.mMaterial = nullptr;
         }
 
+        found = attributes.find(std::make_pair(osg::StateAttribute::ALPHAFUNC, 0));
+        if (found != attributes.end())
+        {
+            // As force shaders is on, we know this is really a RemovedAlphaFunc
+            const osg::StateSet::RefAttributePair& rap = found->second;
+            accumulateState(state.mAlphaFunc, static_cast<osg::AlphaFunc*>(rap.first.get()), state.mAlphaFuncOverride, rap.second);
+        }
+
         // 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())
@@ -113,16 +132,44 @@ StateGraph* ShadowsBin::cullStateGraph(StateGraph* sg, StateGraph* root, std::un
             leaf->_parent = sg_new;
             sg_new->_leaves.push_back(leaf);
         }
-        return sg_new;
+        sg = sg_new;
     }
+
+    // GL_ALWAYS is set by default by mwshadowtechnique
+    if (state.mAlphaFunc && state.mAlphaFunc->getFunction() != GL_ALWAYS)
+    {
+        sg_new = sg->find_or_insert(mAlphaFuncShaders[state.mAlphaFunc->getFunction() - GL_NEVER]);
+        for (RenderLeaf* leaf : sg->_leaves)
+        {
+            leaf->_parent = sg_new;
+            sg_new->_leaves.push_back(leaf);
+        }
+        sg = sg_new;
+    }
+
     return sg;
 }
 
+void ShadowsBin::addPrototype(const std::string & name, const std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER>& castingPrograms)
+{
+    sCastingPrograms = castingPrograms;
+    osg::ref_ptr<osgUtil::RenderBin> bin(new ShadowsBin);
+    osgUtil::RenderBin::addRenderBinPrototype(name, bin);
+}
+
+inline bool ShadowsBin::State::needTexture() const
+{
+    return mAlphaBlend || (mAlphaFunc && mAlphaFunc->getFunction() != GL_ALWAYS);
+}
+
 bool ShadowsBin::State::needShadows() const
 {
-    if (!mMaterial)
+    if (mAlphaFunc && mAlphaFunc->getFunction() == GL_NEVER)
-        return true;
+        return false;
+    // other alpha func + material combinations might be skippable
+    if (mAlphaBlend && mMaterial)
         return materialNeedShadows(mMaterial);
+    return true;
 }
 
 void ShadowsBin::sortImplementation()

components/sceneutil/shadowsbin.hpp

@@ -1,11 +1,13 @@
 #ifndef OPENMW_COMPONENTS_SCENEUTIL_SHADOWBIN_H
 #define OPENMW_COMPONENTS_SCENEUTIL_SHADOWBIN_H
+#include <array>
 #include <unordered_set>
 #include <osgUtil/RenderBin>
 
 namespace osg
 {
     class Material;
+    class AlphaFunc;
 }
 
 namespace SceneUtil
@@ -15,8 +17,12 @@ namespace SceneUtil
     class ShadowsBin : public osgUtil::RenderBin
     {
     private:
+        static std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER> sCastingPrograms;
+
         osg::ref_ptr<osg::StateSet> mNoTestStateSet;
         osg::ref_ptr<osg::StateSet> mShaderAlphaTestStateSet;
+
+        std::array<osg::ref_ptr<osg::StateSet>, GL_ALWAYS - GL_NEVER> mAlphaFuncShaders;
     public:
         META_Object(SceneUtil, ShadowsBin)
         ShadowsBin();
@@ -24,6 +30,7 @@ namespace SceneUtil
             : osgUtil::RenderBin(rhs, copyop)
             , mNoTestStateSet(rhs.mNoTestStateSet)
             , mShaderAlphaTestStateSet(rhs.mShaderAlphaTestStateSet)
+            , mAlphaFuncShaders(rhs.mAlphaFuncShaders)
             {}
 
         void sortImplementation() override;
@@ -33,8 +40,8 @@ namespace SceneUtil
             State()
                 : mAlphaBlend(false)
                 , mAlphaBlendOverride(false)
-                , mAlphaTest(false)
+                , mAlphaFunc(nullptr)
-                , mAlphaTestOverride(false)
+                , mAlphaFuncOverride(false)
                 , mMaterial(nullptr)
                 , mMaterialOverride(false)
                 , mImportantState(false)
@@ -42,33 +49,29 @@ namespace SceneUtil
 
             bool mAlphaBlend;
             bool mAlphaBlendOverride;
-            bool mAlphaTest;
+            osg::AlphaFunc* mAlphaFunc;
-            bool mAlphaTestOverride;
+            bool mAlphaFuncOverride;
             osg::Material* mMaterial;
             bool mMaterialOverride;
             bool mImportantState;
-            bool needTexture() const { return mAlphaBlend || mAlphaTest; }
+            bool needTexture() 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;
+                return !needShadows() || needTexture() || mAlphaBlendOverride || mAlphaFuncOverride || mMaterialOverride || mImportantState;
             }
         };
 
         osgUtil::StateGraph* 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, const std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER>& castingPrograms);
-        {
-            osg::ref_ptr<osgUtil::RenderBin> bin (new ShadowsBin);
-            osgUtil::RenderBin::addRenderBinPrototype(name, bin);
-        }
     };
 
     class ShadowsBinAdder
     {
         public:
-        ShadowsBinAdder(const std::string& name){ ShadowsBin::addPrototype(name); }
+        ShadowsBinAdder(const std::string& name, const std::array<osg::ref_ptr<osg::Program>, GL_ALWAYS - GL_NEVER>& castingPrograms){ ShadowsBin::addPrototype(name, castingPrograms); }
     };
 
 }

components/shader/removedalphafunc.cpp

@@ -0,0 +1,27 @@
+#include "removedalphafunc.hpp"
+
+#include <cassert>
+
+#include <osg/State>
+
+namespace Shader
+{
+    std::array<osg::ref_ptr<RemovedAlphaFunc>, GL_ALWAYS - GL_NEVER> RemovedAlphaFunc::sInstances{
+        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr
+    };
+
+    osg::ref_ptr<RemovedAlphaFunc> RemovedAlphaFunc::getInstance(GLenum func)
+    {
+        assert(func >= GL_NEVER && func <= GL_ALWAYS);
+        if (!sInstances[func - GL_NEVER])
+            sInstances[func - GL_NEVER] = new RemovedAlphaFunc(static_cast<osg::AlphaFunc::ComparisonFunction>(func), 1.0);
+        return sInstances[func - GL_NEVER];
+    }
+
+    void RemovedAlphaFunc::apply(osg::State & state) const
+    {
+        // Hopefully, anything genuinely requiring the default alpha func of GL_ALWAYS explicitly sets it
+        if (!state.getGlobalDefaultAttribute(ALPHAFUNC)->getType() != getType())
+            state.setGlobalDefaultAttribute(static_cast<const osg::StateAttribute*>(cloneType()));
+    }
+}

components/shader/removedalphafunc.hpp

@@ -0,0 +1,40 @@
+#ifndef OPENMW_COMPONENTS_REMOVEDALPHAFUNC_H
+#define OPENMW_COMPONENTS_REMOVEDALPHAFUNC_H
+
+#include <array>
+
+#include <osg/AlphaFunc>
+
+namespace Shader
+{
+    // State attribute used when shader visitor replaces the deprecated alpha function with a shader
+    // Prevents redundant glAlphaFunc calls and lets the shadowsbin know the stateset had alpha testing
+    class RemovedAlphaFunc : public osg::AlphaFunc
+    {
+    public:
+        // Get a singleton-like instance with the right func (but a default threshold)
+        static osg::ref_ptr<RemovedAlphaFunc> getInstance(GLenum func);
+
+        RemovedAlphaFunc()
+            : osg::AlphaFunc()
+        {}
+
+        RemovedAlphaFunc(ComparisonFunction func, float ref)
+            : osg::AlphaFunc(func, ref)
+        {}
+
+        RemovedAlphaFunc(const RemovedAlphaFunc& raf, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY)
+            : osg::AlphaFunc(raf, copyop)
+        {}
+
+        META_StateAttribute(Shader, RemovedAlphaFunc, ALPHAFUNC);
+
+        void apply(osg::State& state) const override;
+
+    protected:
+        virtual ~RemovedAlphaFunc() = default;
+
+        static std::array<osg::ref_ptr<RemovedAlphaFunc>, GL_ALWAYS - GL_NEVER> sInstances;
+    };
+}
+#endif //OPENMW_COMPONENTS_REMOVEDALPHAFUNC_H

components/shader/shadervisitor.cpp

@@ -1,5 +1,6 @@
 #include "shadervisitor.hpp"
 
+#include <osg/AlphaFunc>
 #include <osg/Geometry>
 #include <osg/Material>
 #include <osg/Texture>
@@ -13,6 +14,7 @@
 #include <components/sceneutil/riggeometry.hpp>
 #include <components/sceneutil/morphgeometry.hpp>
 
+#include "removedalphafunc.hpp"
 #include "shadermanager.hpp"
 
 namespace Shader
@@ -22,6 +24,9 @@ namespace Shader
         : mShaderRequired(false)
         , mColorMode(0)
         , mMaterialOverridden(false)
+        , mAlphaTestOverridden(false)
+        , mAlphaFunc(GL_ALWAYS)
+        , mAlphaRef(1.0)
         , mNormalHeight(false)
         , mTexStageRequiringTangents(-1)
         , mNode(nullptr)
@@ -76,6 +81,34 @@ namespace Shader
         return newStateSet.get();
     }
 
+    osg::UserDataContainer* getWritableUserDataContainer(osg::Object& object)
+    {
+        if (!object.getUserDataContainer())
+            return object.getOrCreateUserDataContainer();
+
+        osg::ref_ptr<osg::UserDataContainer> newUserData = static_cast<osg::UserDataContainer *>(object.getUserDataContainer()->clone(osg::CopyOp::SHALLOW_COPY));
+        object.setUserDataContainer(newUserData);
+        return newUserData.get();
+    }
+
+    osg::StateSet* getRemovedState(osg::StateSet& stateSet)
+    {
+        if (!stateSet.getUserDataContainer())
+            return nullptr;
+
+        return static_cast<osg::StateSet *>(stateSet.getUserDataContainer()->getUserObject("removedState"));
+    }
+
+    void updateRemovedState(osg::UserDataContainer& userData, osg::StateSet* stateSet)
+    {
+        unsigned int index = userData.getUserObjectIndex("removedState");
+        if (index < userData.getNumUserObjects())
+            userData.setUserObject(index, stateSet);
+        else
+            userData.addUserObject(stateSet);
+        stateSet->setName("removedState");
+    }
+
     const char* defaultTextures[] = { "diffuseMap", "normalMap", "emissiveMap", "darkMap", "detailMap", "envMap", "specularMap", "decalMap", "bumpMap" };
     bool isTextureNameRecognized(const std::string& name)
     {
@@ -234,7 +267,13 @@ namespace Shader
         }
 
         const osg::StateSet::AttributeList& attributes = stateset->getAttributeList();
-        for (osg::StateSet::AttributeList::const_iterator it = attributes.begin(); it != attributes.end(); ++it)
+        osg::StateSet::AttributeList removedAttributes;
+        osg::ref_ptr<osg::StateSet> removedState;
+        if (removedState = getRemovedState(*stateset))
+            removedAttributes = removedState->getAttributeList();
+        for (const auto& attributeMap : { attributes, removedAttributes })
+        {
+            for (osg::StateSet::AttributeList::const_iterator it = attributeMap.begin(); it != attributeMap.end(); ++it)
             {
                 if (it->first.first == osg::StateAttribute::MATERIAL)
                 {
@@ -276,7 +315,19 @@ namespace Shader
                         mRequirements.back().mColorMode = colorMode;
                     }
                 }
-            // Eventually, move alpha testing to discard in shader adn remove deprecated state here
+                else if (it->first.first == osg::StateAttribute::ALPHAFUNC)
+                {
+                    if (!mRequirements.back().mAlphaTestOverridden || it->second.second & osg::StateAttribute::PROTECTED)
+                    {
+                        if (it->second.second & osg::StateAttribute::OVERRIDE)
+                            mRequirements.back().mAlphaTestOverridden = true;
+
+                        const osg::AlphaFunc* alpha = static_cast<const osg::AlphaFunc*>(it->second.first.get());
+                        mRequirements.back().mAlphaFunc = alpha->getFunction();
+                        mRequirements.back().mAlphaRef = alpha->getReferenceValue();
+                    }
+                }
+            }
         }
     }
 
@@ -322,6 +373,42 @@ namespace Shader
 
         writableStateSet->addUniform(new osg::Uniform("colorMode", reqs.mColorMode));
 
+        defineMap["alphaFunc"] = std::to_string(reqs.mAlphaFunc);
+        if (reqs.mAlphaFunc != osg::AlphaFunc::ALWAYS)
+        {
+            writableStateSet->addUniform(new osg::Uniform("alphaRef", reqs.mAlphaRef));
+
+            // back up removed state in case recreateShaders gets rid of the shader later
+            osg::ref_ptr<osg::StateSet> removedState;
+            if ((removedState = getRemovedState(*writableStateSet)) && !mAllowedToModifyStateSets)
+                removedState = new osg::StateSet(*removedState, osg::CopyOp::SHALLOW_COPY);
+            if (!removedState)
+                removedState = new osg::StateSet();
+
+            if (writableStateSet->getMode(GL_ALPHA_TEST) != osg::StateAttribute::INHERIT)
+                removedState->setMode(GL_ALPHA_TEST, writableStateSet->getMode(GL_ALPHA_TEST));
+            // This disables the deprecated fixed-function alpha test
+            writableStateSet->setMode(GL_ALPHA_TEST, osg::StateAttribute::OFF | osg::StateAttribute::PROTECTED);
+
+            const auto* alphaFunc = writableStateSet->getAttributePair(osg::StateAttribute::ALPHAFUNC);
+            if (alphaFunc)
+                removedState->setAttribute(alphaFunc->first, alphaFunc->second);
+            // This prevents redundant glAlphaFunc calls while letting the shadows bin still see the test
+            writableStateSet->setAttribute(RemovedAlphaFunc::getInstance(reqs.mAlphaFunc), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
+
+            if (!removedState->getModeList().empty() || !removedState->getAttributeList().empty())
+            {
+                // user data is normally shallow copied so shared with the original stateset
+                osg::ref_ptr<osg::UserDataContainer> writableUserData;
+                if (mAllowedToModifyStateSets)
+                    writableUserData = writableStateSet->getOrCreateUserDataContainer();
+                else
+                    writableUserData = getWritableUserDataContainer(*writableStateSet);
+
+                updateRemovedState(*writableUserData, removedState);
+            }
+        }
+
         osg::ref_ptr<osg::Shader> vertexShader (mShaderManager.getShader(mDefaultVsTemplate, defineMap, osg::Shader::VERTEX));
         osg::ref_ptr<osg::Shader> fragmentShader (mShaderManager.getShader(mDefaultFsTemplate, defineMap, osg::Shader::FRAGMENT));
 
@@ -347,6 +434,25 @@ namespace Shader
             writableStateSet = getWritableStateSet(node);
 
         writableStateSet->removeAttribute(osg::StateAttribute::PROGRAM);
+
+        osg::ref_ptr<osg::StateSet> removedState;
+        if (removedState = getRemovedState(*writableStateSet))
+        {
+            // user data is normally shallow copied so shared with the original stateset
+            osg::ref_ptr<osg::UserDataContainer> writableUserData;
+            if (mAllowedToModifyStateSets)
+                writableUserData = writableStateSet->getUserDataContainer();
+            else
+                writableUserData = getWritableUserDataContainer(*writableStateSet);
+            unsigned int index = writableUserData->getUserObjectIndex("removedState");
+            writableUserData->removeUserObject(index);
+
+            for (const auto& [mode, value] : removedState->getModeList())
+                writableStateSet->setMode(mode, value);
+
+            for (const auto& attribute : removedState->getAttributeList())
+                writableStateSet->setAttribute(attribute.second.first, attribute.second.second);
+        }
     }
 
     bool ShaderVisitor::adjustGeometry(osg::Geometry& sourceGeometry, const ShaderRequirements& reqs)

components/shader/shadervisitor.hpp

@@ -79,6 +79,10 @@ namespace Shader
             int mColorMode;
             
             bool mMaterialOverridden;
+            bool mAlphaTestOverridden;
+
+            GLenum mAlphaFunc;
+            float mAlphaRef;
 
             bool mNormalHeight; // true if normal map has height info in alpha channel
 

files/shaders/CMakeLists.txt

@@ -10,6 +10,7 @@ set(SHADER_FILES
     water_vertex.glsl
     water_fragment.glsl
     water_nm.png
+    alpha.glsl
     objects_vertex.glsl
     objects_fragment.glsl
     terrain_vertex.glsl

files/shaders/alpha.glsl

@@ -0,0 +1,38 @@
+
+#define FUNC_NEVER                          0x0200
+#define FUNC_LESS                           0x0201
+#define FUNC_EQUAL                          0x0202
+#define FUNC_LEQUAL                         0x0203
+#define FUNC_GREATER                        0x0204
+#define FUNC_NOTEQUAL                       0x0205
+#define FUNC_GEQUAL                         0x0206
+#define FUNC_ALWAYS                         0x0207
+
+#if @alphaFunc != FUNC_ALWAYS && @alphaFunc != FUNC_NEVER
+uniform float alphaRef;
+#endif
+
+void alphaTest()
+{
+    #if @alphaFunc == FUNC_NEVER
+        discard;
+    #elif @alphaFunc == FUNC_LESS
+        if (gl_FragData[0].a > alphaRef)
+            discard;
+    #elif @alphaFunc == FUNC_EQUAL
+        if (gl_FragData[0].a != alphaRef)
+            discard;
+    #elif @alphaFunc == FUNC_LEQUAL
+        if (gl_FragData[0].a >= alphaRef)
+            discard;
+    #elif @alphaFunc == FUNC_GREATER
+        if (gl_FragData[0].a < alphaRef)
+            discard;
+    #elif @alphaFunc == FUNC_NOTEQUAL
+        if (gl_FragData[0].a == alphaRef)
+            discard;
+    #elif @alphaFunc == FUNC_GEQUAL
+        if (gl_FragData[0].a <= alphaRef)
+            discard;
+    #endif
+}

files/shaders/objects_fragment.glsl

@@ -67,6 +67,7 @@ varying vec3 passNormal;
 #include "shadows_fragment.glsl"
 #include "lighting.glsl"
 #include "parallax.glsl"
+#include "alpha.glsl"
 
 void main()
 {
@@ -108,6 +109,7 @@ void main()
 
 #if @diffuseMap
     gl_FragData[0] = texture2D(diffuseMap, adjustedDiffuseUV);
+    alphaTest();
 #else
     gl_FragData[0] = vec4(1.0);
 #endif
@@ -164,6 +166,8 @@ void main()
     gl_FragData[0] *= doLighting(passViewPos, normalize(viewNormal), passColor, shadowing);
 #endif
 
+    alphaTest();
+
 #if @envMap && !@preLightEnv
     gl_FragData[0].xyz += texture2D(envMap, envTexCoordGen).xyz * envMapColor.xyz * envLuma;
 #endif

files/shaders/shadowcasting_fragment.glsl

@@ -8,6 +8,8 @@ varying float alphaPassthrough;
 uniform bool useDiffuseMapForShadowAlpha;
 uniform bool alphaTestShadows;
 
+#include "alpha.glsl"
+
 void main()
 {
     gl_FragData[0].rgb = vec3(1.0);
@@ -16,7 +18,10 @@ void main()
     else
         gl_FragData[0].a = alphaPassthrough;
 
-    // Prevent translucent things casting shadow (including the player using an invisibility effect). For now, rely on the deprecated FF test for non-blended stuff.
+    alphaTest();
+
+    // Prevent translucent things casting shadow (including the player using an invisibility effect).
+    // This replaces alpha blending, which obviously doesn't work with depth buffers
     if (alphaTestShadows && gl_FragData[0].a <= 0.5)
         discard;
 }