Added basic code injection fields to osg::Shader,

creation of main shader to ShaderComposer and
collection of ShaderComponent to osg::State.
Also added very basic shader set up in osgshadecomposition example.

examples/osgshadercomposition/osgshadercomposition.cpp

@@ -29,6 +29,30 @@ osg::Node* createSceneGraph(osg::ArgumentParser& arguments)
     osg::ShaderAttribute* sa = new osg::ShaderAttribute;
     stateset->setAttribute(sa);
 
+    {
+        const char shader_str[] =
+            "vec4 colour()\n"
+            "{\n"
+            "    return vec4(1.0,0.5,1.0,1.0);\n"
+           "}\n";
+
+        osg::Shader* vertex_shader = new osg::Shader(osg::Shader::VERTEX, shader_str);
+        vertex_shader->addCodeInjection(-1,"varying vec4 c;\n");
+        vertex_shader->addCodeInjection(-1,"vec4 colour();\n");
+        vertex_shader->addCodeInjection(0,"gl_Position = ftransform();\n");
+        vertex_shader->addCodeInjection(0,"c = colour();\n");
+
+        sa->addShader(vertex_shader);
+     }
+
+     {
+        osg::Shader* fragment_shader = new osg::Shader(osg::Shader::FRAGMENT);
+        fragment_shader->addCodeInjection(-1,"varying vec4 c;\n");
+        fragment_shader->addCodeInjection(0,"gl_FragColor = c;\n");
+
+        sa->addShader(fragment_shader);
+     }
+
     return node;
 }
 
@@ -43,5 +67,17 @@ int main( int argc, char **argv )
 
     viewer.setSceneData(scenegraph.get());
 
+    viewer.realize();
+
+    // enable shader composition
+    osgViewer::Viewer::Windows windows;
+    viewer.getWindows(windows);
+    for(osgViewer::Viewer::Windows::iterator itr = windows.begin();
+        itr != windows.end();
+        ++itr)
+    {
+        (*itr)->getState()->setShaderCompositionEnabled(true);
+    }
+
     return viewer.run();
 }

include/osg/Shader

@@ -25,6 +25,7 @@
 #include <osg/buffered_value>
 
 #include <set>
+#include <map>
 
 namespace osg {
 
@@ -143,6 +144,24 @@ class OSG_EXPORT Shader : public osg::Object
         bool loadShaderSourceFromFile( const std::string& fileName );
 
 
+        /** The code injection map used when generating the main shader during main shader composition.*/
+        typedef std::multimap<float, std::string> CodeInjectionMap;
+
+        /** Add code injection that will be placed in the main shader to enable support for this shader.
+          * The position is set up so that code to be inserted before the main() will have a negative value,
+          * a position between 0 and 1.0 will be inserted in main() and a position greater than 1.0 will
+          * be placed after the main().
+          * During shader composition all the code injections are sorted in ascending order and then
+          * placed in the appropriate section of the main shader. */
+        void addCodeInjection(float position, const std::string& code) { _codeInjectionMap.insert(CodeInjectionMap::value_type(position, code)); }
+
+        /** Get the code injection map.*/
+        CodeInjectionMap& getCodeInjectionMap() { return _codeInjectionMap; }
+
+        /** Get the const code injection map.*/
+        const CodeInjectionMap& getCodeInjectionMap() const { return _codeInjectionMap; }
+
+
 
         /** Resize any per context GLObject buffers to specified size. */
         virtual void resizeGLObjectBuffers(unsigned int maxSize);
@@ -243,6 +262,8 @@ class OSG_EXPORT Shader : public osg::Object
         std::string                     _shaderSource;
         osg::ref_ptr<ShaderBinary>      _shaderBinary;
 
+        CodeInjectionMap                _codeInjectionMap;
+        
         /** osg::Programs that this osg::Shader is attached to */
         typedef std::set< osg::Program* > ProgramSet;
         ProgramSet                      _programSet;

include/osg/ShaderComposer

@@ -38,11 +38,13 @@ class OSG_EXPORT ShaderComposer : public osg::Object
 
         typedef std::vector< const osg::Shader* >  Shaders;
         virtual osg::Shader* composeMain(const Shaders& shaders);
+        virtual void addShaderToProgram(Program* program, const Shaders& shaders);
 
     protected:
 
         virtual ~ShaderComposer();
 
+
         typedef std::map< ShaderComponents, ref_ptr<Program> > ProgramMap;
         ProgramMap _programMap;
 

include/osg/State

@@ -142,6 +142,12 @@ class OSG_EXPORT State : public Referenced, public Observer
         inline unsigned int getContextID() const { return _contextID; }
 
 
+        /* Set whether shader composition is enabled.*/
+        void setShaderCompositionEnabled(bool flag) { _shaderCompositionEnabled = flag; }
+
+        /* Get whether shader composition is enabled.*/
+        bool getShaderCompositionEnabled() const { return _shaderCompositionEnabled; }
+
         /** Set the ShaderComposor object that implements shader composition.*/
         void setShaderComposer(ShaderComposer* sc) { _shaderComposer = sc; }
 
@@ -250,6 +256,8 @@ class OSG_EXPORT State : public Referenced, public Observer
          */
         void apply();
 
+        /** Apply any shader composed state.*/
+        void applyShaderComposition();
 
         /** Set whether a particular OpenGL mode is valid in the current graphics context.
           * Use to disable OpenGL modes that are not supported by current graphics drivers/context.*/

src/osg/Shader.cpp

@@ -201,7 +201,8 @@ Shader::Shader(const Shader& rhs, const osg::CopyOp& copyop):
     _type(rhs._type),
     _shaderFileName(rhs._shaderFileName),
     _shaderSource(rhs._shaderSource),
-    _shaderBinary(rhs._shaderBinary)
+    _shaderBinary(rhs._shaderBinary),
+    _codeInjectionMap(rhs._codeInjectionMap)
 {
 }
 

src/osg/ShaderComposer.cpp

@@ -77,54 +77,19 @@ osg::Program* ShaderComposer::getOrCreateProgram(const ShaderComponents& shaderC
 
     if (!vertexShaders.empty())
     {
-        ShaderMainMap::iterator itr = _shaderMainMap.find(vertexShaders);
-        if (itr == _shaderMainMap.end())
-        {
-            // no vertex shader in map yet, need to compose a new main shader
-            osg::Shader* mainShader = composeMain(vertexShaders);
-            _shaderMainMap[vertexShaders] = mainShader;
-            program->addShader(mainShader);
-        }
-        else
-        {
-            program->addShader(itr->second.get());
-        }
+        addShaderToProgram(program.get(), vertexShaders);
     }
 
     if (!geometryShaders.empty())
     {
-        ShaderMainMap::iterator itr = _shaderMainMap.find(geometryShaders);
-        if (itr == _shaderMainMap.end())
-        {
-            // no vertex shader in map yet, need to compose a new main shader
-            osg::Shader* mainShader = composeMain(geometryShaders);
-            _shaderMainMap[geometryShaders] = mainShader;
-            program->addShader(mainShader);
-        }
-        else
-        {
-            program->addShader(itr->second.get());
-        }
+        addShaderToProgram(program.get(), geometryShaders);
     }
 
-
     if (!fragmentShaders.empty())
     {
-        ShaderMainMap::iterator itr = _shaderMainMap.find(fragmentShaders);
-        if (itr == _shaderMainMap.end())
-        {
-            // no vertex shader in map yet, need to compose a new main shader
-            osg::Shader* mainShader = composeMain(fragmentShaders);
-            _shaderMainMap[fragmentShaders] = mainShader;
-            program->addShader(mainShader);
-        }
-        else
-        {
-            program->addShader(itr->second.get());
-        }
+        addShaderToProgram(program.get(), fragmentShaders);
     }
 
-
     // assign newly created program to map.
     _programMap[shaderComponents] = program;
 
@@ -133,8 +98,93 @@ osg::Program* ShaderComposer::getOrCreateProgram(const ShaderComponents& shaderC
     return program.get();
 }
 
+void ShaderComposer::addShaderToProgram(Program* program, const Shaders& shaders)
+{
+    ShaderMainMap::iterator itr = _shaderMainMap.find(shaders);
+    if (itr == _shaderMainMap.end())
+    {
+        // no vertex shader in map yet, need to compose a new main shader
+        osg::Shader* mainShader = composeMain(shaders);
+        _shaderMainMap[shaders] = mainShader;
+        program->addShader(mainShader);
+    }
+    else
+    {
+        program->addShader(itr->second.get());
+    }
+
+    for(Shaders::const_iterator itr = shaders.begin();
+        itr != shaders.end();
+        ++itr)
+    {
+        Shader* shader = const_cast<Shader*>(*itr);
+        if (!(shader->getShaderSource().empty()) || shader->getShaderBinary())
+        {
+            program->addShader(shader);
+        }
+    }
+}
+
 osg::Shader* ShaderComposer::composeMain(const Shaders& shaders)
 {
     OSG_NOTICE<<"ShaderComposer::composeMain(Shaders) shaders.size()=="<<shaders.size()<<std::endl;
-    return 0;
+
+
+    // collect the shader type and the code injection from each of the contributing shaders
+    Shader::Type type = Shader::UNDEFINED;
+    Shader::CodeInjectionMap codeInjectionMap;
+    for(Shaders::const_iterator itr = shaders.begin();
+        itr != shaders.end();
+        ++itr)
+    {
+        const Shader* shader = *itr;
+        if (type == Shader::UNDEFINED)
+        {
+            type = shader->getType();
+        }
+        else if (type != shader->getType())
+        {
+            OSG_NOTICE<<"Warning:ShaderComposer::composeMain() mixing different types of Shaders prohibited."<<std::endl;
+            continue;
+        }
+
+        const Shader::CodeInjectionMap& cim = shader->getCodeInjectionMap();
+        for(Shader::CodeInjectionMap::const_iterator citr = cim.begin();
+            citr != cim.end();
+            ++citr)
+        {
+            codeInjectionMap.insert(*citr);
+        }
+    }
+
+    // collect together the different parts of the main shader
+    std::string before_main;
+    std::string in_main;
+    std::string after_main;
+
+    for(Shader::CodeInjectionMap::iterator citr = codeInjectionMap.begin();
+        citr != codeInjectionMap.end();
+        ++citr)
+    {
+        float position = citr->first;
+        if (position<0.0) before_main += citr->second;
+        else if (position<=1.0) in_main += citr->second;
+        else after_main += citr->second;
+    }
+
+    // assembly the final main shader source
+    std::string full_source;
+    full_source += before_main;
+    full_source += std::string("void main(void)\n");
+    full_source += std::string("{\n");
+    full_source += in_main;
+    full_source += std::string("}\n");
+    full_source += after_main;
+
+
+    ref_ptr<Shader> mainShader = new Shader(type, full_source);
+
+    _shaderMainMap[shaders] = mainShader;
+
+    return mainShader.get();
 }

src/osg/State.cpp

@@ -42,7 +42,7 @@ State::State():
     _graphicsContext = 0;
     _contextID = 0;
 
-    _shaderCompositionEnabled = false; // true;
+    _shaderCompositionEnabled = false;
     _shaderCompositionDirty = true;
     _shaderComposer = new ShaderComposer;
     _currentShaderCompositionProgram = 0L;
@@ -515,21 +515,7 @@ void State::apply(const StateSet* dstate)
             else if (unit<_textureAttributeMapList.size()) applyAttributeMapOnTexUnit(unit,_textureAttributeMapList[unit]);
         }
 
-        if (_shaderCompositionEnabled)
-        {
-            if (_shaderCompositionDirty)
-            {
-                // build lits of current ShaderComponents
-                ShaderComponents shaderComponents;
-                _currentShaderCompositionProgram = _shaderComposer->getOrCreateProgram(shaderComponents);
-            }
-
-            if (_currentShaderCompositionProgram)
-            {
-                Program::PerContextProgram* pcp = _currentShaderCompositionProgram->getPCP(_contextID);
-                if (_lastAppliedProgramObject != pcp) applyAttribute(_currentShaderCompositionProgram);
-            }
-        }
+        applyShaderComposition();
 
         applyUniformList(_uniformMap,dstate->getUniformList());
     }
@@ -562,11 +548,45 @@ void State::apply()
         if (unit<_textureAttributeMapList.size()) applyAttributeMapOnTexUnit(unit,_textureAttributeMapList[unit]);
     }
 
+    applyShaderComposition();
+
     applyUniformMap(_uniformMap);
 
     if (_checkGLErrors==ONCE_PER_ATTRIBUTE) checkGLErrors("end of State::apply()");
 }
 
+void State::applyShaderComposition()
+{
+    if (_shaderCompositionEnabled)
+    {
+        if (_shaderCompositionDirty)
+        {
+            // build lits of current ShaderComponents
+            ShaderComponents shaderComponents;
+
+            for(AttributeMap::iterator itr = _attributeMap.begin();
+                itr != _attributeMap.end();
+                ++itr)
+            {
+                AttributeStack& as = itr->second;
+                if (as.last_applied_shadercomponent)
+                {
+                    shaderComponents.push_back(const_cast<ShaderComponent*>(as.last_applied_shadercomponent));
+                }
+            }
+
+            _currentShaderCompositionProgram = _shaderComposer->getOrCreateProgram(shaderComponents);
+        }
+
+        if (_currentShaderCompositionProgram)
+        {
+            Program::PerContextProgram* pcp = _currentShaderCompositionProgram->getPCP(_contextID);
+            if (_lastAppliedProgramObject != pcp) applyAttribute(_currentShaderCompositionProgram);
+        }
+    }
+}
+
+
 void State::haveAppliedMode(StateAttribute::GLMode mode,StateAttribute::GLModeValue value)
 {
     haveAppliedMode(_modeMap,mode,value);