/** 
 * @file llgl.h
 * @brief LLGL definition
 *
 * $LicenseInfo:firstyear=2001&license=viewergpl$
 * 
 * Copyright (c) 2001-2009, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 * 
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
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 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

#ifndef LL_LLGL_H
#define LL_LLGL_H

// This file contains various stuff for handling gl extensions and other gl related stuff.

#include <string>
#include <map>

#include "llerror.h"
#include "v4color.h"
#include "llstring.h"
#include "stdtypes.h"
#include "v4math.h"
#include "llplane.h"
#include "llgltypes.h"

#include "llglheaders.h"
#include "glh/glh_linear.h"

extern BOOL gDebugGL;

#define LL_GL_ERRS LL_ERRS("RenderState")

class LLSD;

// Manage GL extensions...
class LLGLManager
{
public:
	LLGLManager();

	bool initGL();
	void shutdownGL();

	void initWGL(); // Initializes stupid WGL extensions

	std::string getRawGLString(); // For sending to simulator

	BOOL mInited;
	BOOL mIsDisabled;

	// Extensions used by everyone
	BOOL mHasMultitexture;
	S32	 mNumTextureUnits;
	BOOL mHasMipMapGeneration;
	BOOL mHasCompressedTextures;
	BOOL mHasFramebufferObject;
	BOOL mHasFramebufferMultisample;
	
	// ARB Extensions
	BOOL mHasVertexBufferObject;
	BOOL mHasPBuffer;
	BOOL mHasShaderObjects;
	BOOL mHasVertexShader;
	BOOL mHasFragmentShader;
	BOOL mHasOcclusionQuery;
	BOOL mHasPointParameters;
	BOOL mHasDrawBuffers;
	BOOL mHasDepthClamp;

	// Other extensions.
	BOOL mHasAnisotropic;
	BOOL mHasARBEnvCombine;
	BOOL mHasCubeMap;

	// Vendor-specific extensions
	BOOL mIsATI;
	BOOL mIsNVIDIA;
	BOOL mIsIntel;
	BOOL mIsGF2or4MX;
	BOOL mIsGF3;
	BOOL mIsGFFX;
	BOOL mATIOffsetVerticalLines;
	BOOL mATIOldDriver;

	// Whether this version of GL is good enough for SL to use
	BOOL mHasRequirements;

	// Misc extensions
	BOOL mHasSeparateSpecularColor;
	
	S32 mDriverVersionMajor;
	S32 mDriverVersionMinor;
	S32 mDriverVersionRelease;
	F32 mGLVersion; // e.g = 1.4
	std::string mDriverVersionVendorString;

	S32 mVRAM; // VRAM in MB
	S32 mGLMaxVertexRange;
	S32 mGLMaxIndexRange;
	
	void getPixelFormat(); // Get the best pixel format

	std::string getGLInfoString();
	void printGLInfoString();
	void getGLInfo(LLSD& info);

	// In ALL CAPS
	std::string mGLVendor;
	std::string mGLVendorShort;

	// In ALL CAPS
	std::string mGLRenderer;

private:
	void initExtensions();
	void initGLStates();
	void initGLImages();
};

extern LLGLManager gGLManager;

class LLQuaternion;
class LLMatrix4;

void rotate_quat(LLQuaternion& rotation);

void flush_glerror(); // Flush GL errors when we know we're handling them correctly.

void assert_glerror();

void clear_glerror();

//#if LL_DEBUG
# define stop_glerror() assert_glerror()
# define llglassertok() assert_glerror()
//#else
//# define stop_glerror()
//# define llglassertok()
//#endif

#define llglassertok_always() assert_glerror()

////////////////////////
//
// Note: U32's are GLEnum's...
//

// This is a class for GL state management

/*
	GL STATE MANAGEMENT DESCRIPTION

	LLGLState and its two subclasses, LLGLEnable and LLGLDisable, manage the current 
	enable/disable states of the GL to prevent redundant setting of state within a 
	render path or the accidental corruption of what state the next path expects.

	Essentially, wherever you would call glEnable set a state and then
	subsequently reset it by calling glDisable (or vice versa), make an instance of 
	LLGLEnable with the state you want to set, and assume it will be restored to its
	original state when that instance of LLGLEnable is destroyed.  It is good practice
	to exploit stack frame controls for optimal setting/unsetting and readability of 
	code.  In llglstates.h, there are a collection of helper classes that define groups
	of enables/disables that can cause multiple states to be set with the creation of
	one instance.  

	Sample usage:

	//disable lighting for rendering hud objects
	//INCORRECT USAGE
	LLGLEnable lighting(GL_LIGHTING);
	renderHUD();
	LLGLDisable lighting(GL_LIGHTING);

	//CORRECT USAGE
	{
		LLGLEnable lighting(GL_LIGHTING);
		renderHUD();
	}

	If a state is to be set on a conditional, the following mechanism
	is useful:

	{
		LLGLEnable lighting(light_hud ? GL_LIGHTING : 0);
		renderHUD();
	}

	A LLGLState initialized with a parameter of 0 does nothing.

	LLGLState works by maintaining a map of the current GL states, and ignoring redundant
	enables/disables.  If a redundant call is attempted, it becomes a noop, otherwise,
	it is set in the constructor and reset in the destructor.  

	For debugging GL state corruption, running with debug enabled will trigger asserts
	if the existing GL state does not match the expected GL state.

*/
class LLGLState
{
public:
	static void initClass();
	static void restoreGL();

	static void resetTextureStates();
	static void dumpStates();
	static void checkStates(const std::string& msg = "");
	static void checkTextureChannels(const std::string& msg = "");
	static void checkClientArrays(const std::string& msg = "", U32 data_mask = 0x0001);
	
protected:
	static std::map<LLGLenum, LLGLboolean> sStateMap;
	
public:
	enum { CURRENT_STATE = -2 };
	LLGLState(LLGLenum state, S32 enabled = CURRENT_STATE);
	~LLGLState();
	void setEnabled(S32 enabled);
	void enable() { setEnabled(TRUE); }
	void disable() { setEnabled(FALSE); }
protected:
	LLGLenum mState;
	BOOL mWasEnabled;
	BOOL mIsEnabled;
};

// New LLGLState class wrappers that don't depend on actual GL flags.
class LLGLEnableBlending : public LLGLState
{
public:
	LLGLEnableBlending(bool enable);
};

class LLGLEnableAlphaReject : public LLGLState
{
public:
	LLGLEnableAlphaReject(bool enable);
};

/// TODO: Being deprecated.
class LLGLEnable : public LLGLState
{
public:
	LLGLEnable(LLGLenum state) : LLGLState(state, TRUE) {}
};

/// TODO: Being deprecated.
class LLGLDisable : public LLGLState
{
public:
	LLGLDisable(LLGLenum state) : LLGLState(state, FALSE) {}
};

/*
  Store and modify projection matrix to create an oblique
  projection that clips to the specified plane.  Oblique
  projections alter values in the depth buffer, so this
  class should not be used mid-renderpass.  

  Restores projection matrix on destruction.
  GL_MODELVIEW_MATRIX is active whenever program execution
  leaves this class.
  Does not stack.
  Caches inverse of projection matrix used in gGLObliqueProjectionInverse
*/
class LLGLUserClipPlane 
{
public:
	
	LLGLUserClipPlane(const LLPlane& plane, const glh::matrix4f& modelview, const glh::matrix4f& projection);
	~LLGLUserClipPlane();

	void setPlane(F32 a, F32 b, F32 c, F32 d);

private:
	glh::matrix4f mProjection;
	glh::matrix4f mModelview;
};

/*
  Modify and load projection matrix to push depth values to far clip plane.

  Restores projection matrix on destruction.
  GL_MODELVIEW_MATRIX is active whenever program execution
  leaves this class.
  Does not stack.
*/
class LLGLSquashToFarClip
{
public:
	LLGLSquashToFarClip(glh::matrix4f projection);
	~LLGLSquashToFarClip();
};

/*
	Generic pooling scheme for things which use GL names (used for occlusion queries and vertex buffer objects).
	Prevents thrashing of GL name caches by avoiding calls to glGenFoo and glDeleteFoo.
*/
class LLGLNamePool
{
public:
	struct NameEntry
	{
		GLuint name;
		BOOL used;
	};

	struct CompareUsed
	{
		bool operator()(const NameEntry& lhs, const NameEntry& rhs)
		{
			return lhs.used < rhs.used;  //FALSE entries first
		}
	};

	typedef std::vector<NameEntry> name_list_t;
	name_list_t mNameList;

	LLGLNamePool();
	virtual ~LLGLNamePool();
	
	void upkeep();
	void cleanup();
	
	GLuint allocate();
	void release(GLuint name);
	
	static void registerPool(LLGLNamePool* pool);
	static void upkeepPools();
	static void cleanupPools();

protected:
	typedef std::vector<LLGLNamePool*> pool_list_t;
	static pool_list_t sInstances;
	
	virtual GLuint allocateName() = 0;
	virtual void releaseName(GLuint name) = 0;
};

extern LLMatrix4 gGLObliqueProjectionInverse;

#include "llglstates.h"

void init_glstates();
void enable_vertex_weighting(const S32 index);
void disable_vertex_weighting(const S32 index);
void enable_binormals(const S32 index);
void disable_binormals(const S32 index);
void enable_cloth_weights(const S32 index);
void disable_cloth_weights(const S32 index);
void set_vertex_weights(const S32 index, const U32 stride, const F32 *weights);
void set_vertex_clothing_weights(const S32 index, const U32 stride, const LLVector4 *weights);
void set_binormals(const S32 index, const U32 stride, const LLVector3 *binormals);
void parse_gl_version( S32* major, S32* minor, S32* release, std::string* vendor_specific );

extern BOOL gClothRipple;
extern BOOL gNoRender;
#endif // LL_LLGL_H