Allow a <parameters> section of a material definition, to pass parameters straight into the effect.

simgear/scene/material/mat.cxx

@@ -388,6 +388,13 @@ SGMaterial::read_properties(const SGReaderWriterOptions* options,
             glyphs[name] = new SGMaterialGlyph(glyph_nodes[i]);
     }
     
+    // Read parameters entry, which is passed into the effect
+    if (props->hasChild("parameters")) {
+        parameters = props->getChild("parameters");
+    } else {
+        parameters = new SGPropertyNode();
+    }
+
     // Read conditions node
     const SGPropertyNode *conditionNode = props->getChild("condition");
     if (conditionNode) {
@@ -481,7 +488,10 @@ void SGMaterial::buildEffectProperties(const SGReaderWriterOptions* options)
     ref_ptr<SGMaterialUserData> user = new SGMaterialUserData(this);
     SGPropertyNode_ptr propRoot = new SGPropertyNode();
     makeChild(propRoot, "inherits-from")->setStringValue(effect);
+    
     SGPropertyNode* paramProp = makeChild(propRoot, "parameters");
+    copyProperties(parameters, paramProp);
+    
     SGPropertyNode* materialProp = makeChild(paramProp, "material");
     makeChild(materialProp, "ambient")->setValue(SGVec4d(ambient));
     makeChild(materialProp, "diffuse")->setValue(SGVec4d(diffuse));

simgear/scene/material/mat.hxx

@@ -485,6 +485,9 @@ private:
   // Condition, indicating when this material is active
   SGSharedPtr<const SGCondition> condition;
   
+  // Parameters from the materials file
+  const SGPropertyNode* parameters;
+
   ////////////////////////////////////////////////////////////////////
   // Internal constructors and methods.
   ////////////////////////////////////////////////////////////////////