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dopplex

OpenGL Implementing Effect Scripting

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dopplex    164
So I took a first pass at implementing effect scripting, and was hoping to get some feedback on the approach I took. While I'm pretty happy with the approach (which seems extremely flexible), I'm still (relatively) new to game programming and have never had any real code review, so I have a constant worry that I'm making a large number of high level and low level errors. The most recent thing I'm working on is implementing SAS scripting for my effects (I'm using cgfx with OpenGL, though I think most of the things here would be equally valid (minus slight implementation differences) in DirectX.) So here's what I'm doing: Data:
union ScriptArg
{
	unsigned int uiArg;
	float floatArg;
	float vec2Arg[2];
	float vec3Arg[3];
	float vec4Arg[4];
};

typedef void(*ScriptCommand)(IFXScript &scriptInstance, const ScriptArg &scriptArg);

struct ScriptElem
{
	ScriptCommand command;
	ScriptArg	  arg;
};

typedef void(*ScriptCommandBuilder)(IFXScript &scriptInstance, ScriptElem &scriptElem, const std::string &stringArg);

typedef void(*RenderFunc)();

So I'm essentially just storing a function pointer corresponding to whatever implementation I have of the SAS command along with a union holding whatever the argument was (With some preprocessing of the arguments done - each command has its own function for putting together its ScriptElem struct. And here are the script classes:
class IFXScript
{
public:
	RenderFunc tempFunc;
	unsigned int effectHandle;
	unsigned int handle;
	std::vector<ScriptElem> script;
	IFXScript(){};
	~IFXScript(){};


	unordered_map<unsigned int, TexInfo> TextureMap;  
	void AddElem(const std::string &commandString, const std::string &argString);
	void AddTex(unsigned int paramNum);
	void Run(RenderFunc);
	virtual void SetSurface() = 0;  

};

class TechniqueScript : public IFXScript
{
public:
	TechniqueScript() {};
	TechniqueScript(unsigned int techniqueHandle, unsigned int effect_handle);
	~TechniqueScript();
	unordered_map<unsigned int, PassScript*> passMap;  
	SurfConfig Surface;
	inline void SetSurface() {SetSurf(Surface);};
};

class PassScript : public IFXScript
{
public:
	TechniqueScript* parentTechnique;
	unsigned int passHandle;
	std::vector<ScriptElem> script;
	PassScript() {};
	PassScript(unsigned int passHandle, unsigned int effect_handle, TechniqueScript* parent);
	~PassScript() {};

	//Sets the FBO with the rendertargets 
	//currently defined in the TechniqueScript's
	//Surface variable.  PassScript will pass this
	//up to its parent TechniqueScript
	//Rendertarget change script commands
	//should only change the Surface variable.
	//SetSurface will need to be called before
	//the Draw to actually set the targets
	inline void SetSurface() {parentTechnique->SetSurface();};
};

(I know - nothing is encapsulated. I'm going to go back and fix that once I get a better handle on what I need to create accessor functions for) So after parsing, what I end up with for each Technique or Pass script is a vector full of function pointers and arguments. Running the script is just:
void IFXScript::Run(RenderFunc tFunc)
{
	tempFunc = tFunc;
	vector<ScriptElem>::iterator myScriptIter;
	for (myScriptIter = script.begin(); myScriptIter != script.end(); ++myScriptIter)
	{
		ScriptElem &curElem = *myScriptIter;
		(curElem.command)(*this, curElem.arg);
	};
};

I'm midway through implementing the actual command functions at the moment. Mostly, I just want to know if this approach to implementing the scripting looks good on paper, and whether I'm making any severely suboptimal choices in my implementation. I'm worrying more about the overall architecture of it, and if I'm unwittingly making a mistake that will hurt me in the long run. Any constructive criticism would be much appreciated!

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