more robust shader reloading

include/ACGL/OpenGL/Controller/ShaderProgramControlFiles.hh

@@ -159,8 +159,8 @@ protected:
     SharedLocationMappings mUniformBufferLocations;
 
 private:
-    // set attribute & fragdata locations prior to shader program linking
-    void setBindings(SharedShaderProgram &_shaderProgram);
+    // set attribute, UBO & fragdata locations and links the program
+    bool setBindings(SharedShaderProgram &_shaderProgram);
 };
 
 } // OpenGL

src/ACGL/OpenGL/Controller/ShaderControlFile.cc

@@ -45,8 +45,19 @@ bool ShaderControlFile::update(SharedShader& shader)
     if(fileIsUpToDate())
         return false;
 
-    if(!shader->setFromFile(mFullFilePath))
-        return false;
+    { // try to compile the source in another shader, only proceed if that worked!
+        Shader dummy( shader->getType() );
+        if (!dummy.setFromFile(mFullFilePath)) {
+
+            // we had a shader compile error, update the timestamp to prevent a second try
+            // of compiling the exact same (non-working) shader again
+            updateFileModificationTime();
+            return false;
+        }
+    }
+
+    // it worked, so load the source in "our" shader:
+    shader->setFromFile(mFullFilePath);
 
     updateFileModificationTime();
     return true;

src/ACGL/OpenGL/Controller/ShaderProgramControlFiles.cc

@@ -113,27 +113,27 @@ SharedShaderProgram ShaderProgramControlFiles::create(void)
         }
     }
 
-    if (!shaderProgram->link()) {
-        return SharedShaderProgram(); // linking failed
+    if (!setBindings( shaderProgram )) {
+        return SharedShaderProgram(); // e.g. linking failed
     }
-    setBindings( shaderProgram ); // will relink, but needs a linked program :-(
     openGLCommonErrorOccured();
     updateFileModificationTimes();
     return shaderProgram;
 }
 
-// program has to be linked before calling setBindings!
-void ShaderProgramControlFiles::setBindings(SharedShaderProgram &_shaderProgram)
+// will get called from the create and update functions:
+bool ShaderProgramControlFiles::setBindings(SharedShaderProgram &_shaderProgram)
 {
     openGLRareErrorOccured();
+    _shaderProgram->link();
+
 #   if (ACGL_OPENGL_VERSION >= 30)
-        _shaderProgram->setFragmentDataLocations( mFragmentDataLocations ); // will relink on it's own
+        _shaderProgram->setFragmentDataLocations( mFragmentDataLocations ); // might relink on it's own
         openGLRareErrorOccured();
 
-        _shaderProgram->setAttributeLocations( mAttributeLocations );
         SharedLocationMappings oldAttributeMap = _shaderProgram->getAttributeLocations();
         mAttributeLocations->addLocations( oldAttributeMap ); // add as many old locations as possible without destoying the location map
-        _shaderProgram->setAttributeLocations( mAttributeLocations ); // will relink on it's own
+        _shaderProgram->setAttributeLocations( mAttributeLocations ); // might relink on it's own
 
         openGLRareErrorOccured();
 #   else
@@ -142,6 +142,9 @@ void ShaderProgramControlFiles::setBindings(SharedShaderProgram &_shaderProgram)
         }
 #   endif
 
+    // in case the attribute/fragdata locations did not change, those calls will not call glLinkProgram
+    if (_shaderProgram->link() == false) return false;
+
     // uniform block binding have to be set after linking!
     if ( mUniformBufferLocations->getSize() > 0) {
 #       if (ACGL_OPENGL_VERSION >= 31)
@@ -154,14 +157,14 @@ void ShaderProgramControlFiles::setBindings(SharedShaderProgram &_shaderProgram)
             Utils::error() << "can't set uniform buffer locations on OpenGL < 3.1" << std::endl;
 #       endif
     }
+
+    return true;
 }
 
 bool ShaderProgramControlFiles::update(SharedShaderProgram &_shaderProgram)
 {
     bool update = false;
 
-    //Utils::debug() << "updating " << mResourceName << std::endl;
-
     for (std::vector<std::string>::size_type i = 0; i < mFileNames.size(); ++i) {
         if ( mShaderType[i] != GL_INVALID_VALUE ) {
             update |= ShaderFileManager::the()->update( mFileNames[i] );
@@ -170,10 +173,12 @@ bool ShaderProgramControlFiles::update(SharedShaderProgram &_shaderProgram)
 
     if ((!filesAreUpToDate() ) || (update))
     {
-        Utils::debug() << "updating " << mResourceName << " AND RELINKING!" << std::endl;
-        setBindings( _shaderProgram );
+        // at least one shader was updated, so update the program:
+        // keep the old mappings and relink:
+        Utils::debug() << "updating " << mResourceName << std::endl;
+        bool shaderProgramOK = setBindings( _shaderProgram ); // will relink, and set UBO bindings (don't relink after this!)
         updateFileModificationTimes();
-        return _shaderProgram->link();
+        return shaderProgramOK;
     }
 
     return false;