/**
 * @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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 * $/LicenseInfo$
 */

#ifndef LL_LLGL_H
#define LL_LLGL_H

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

#include <list>

#include "llcolor4.h"
#include "hbfastmap.h"
#include "llglheaders.h"
#include "llinstancetracker.h"
#include "llmatrix4a.h"
#include "llplane.h"
#include "llstring.h"

extern bool gDebugGL;
// Global flag for dual-renderer support (EE/WL and PBR). HB
extern bool gUsePBRShaders;

class LLSD;

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

public:
	LLGLManager();

	bool initGL();
	void shutdownGL();

#if LL_WINDOWS
	void initWGL(HDC dc);			// Initializes stupid WGL extensions
#endif

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

	void getPixelFormat();			// Get the best pixel format

	void printGLInfoString();
	void getGLInfo(LLSD& info);

	void asLLSD(LLSD& info);

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

public:
	S32 mDriverVersionMajor;
	S32 mDriverVersionMinor;
	S32 mDriverVersionRelease;
	F32 mGLVersion;				// E.g = 3.2
	S32 mGLSLVersionMajor;
	S32 mGLSLVersionMinor;

	S32 mVRAM;					// Total VRAM in MB
	S32 mTexVRAM;				// VRAM reserved for textures in MB
	S32 mGLMaxVertexRange;
	S32 mGLMaxIndexRange;
	S32 mGLMaxTextureSize;

	std::string mDriverVersionVendorString;
	std::string mGLVersionString;

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

	// In ALL CAPS
	std::string mGLRenderer;

	// Limits
	S32 mMaxSamples;
	S32 mNumTextureImageUnits;
	S32 mMaxUniformBlockSize;
	F32 mMaxAnisotropy;

	// Extensions
#if LL_WINDOWS
	bool mHasAMDAssociations;
#endif
	bool mHasATIMemInfo;
	bool mHasNVXMemInfo;
	bool mHasVertexArrayObject;
	bool mHasSync;
	bool mHasOcclusionQuery2;
	bool mHasTimerQuery;
	bool mHasDepthClamp;
	bool mUseDepthClamp;
	bool mHasAnisotropic;
	bool mHasCubeMapArray;
	bool mHasDebugOutput;
	bool mHasTextureSwizzle;
	bool mHasGpuShader4;
	bool mHasGpuShader5;

	// GPU vendor flags
	bool mIsAMD;
	bool mIsNVIDIA;
	bool mIsIntel;

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

	// Misc extensions
	bool mHasVertexAttribIPointer;

	bool mInited;
	bool mIsDisabled;
};

extern LLGLManager gGLManager;

class LLQuaternion;
class LLMatrix4;

LL_NO_INLINE void log_glerror(const char* file, U32 line, bool crash = false);

#if LL_DEBUG
# define stop_glerror() if (LL_UNLIKELY(gDebugGL)) log_glerror(__FILE__, __LINE__, true)
#else
# define stop_glerror() if (LL_UNLIKELY(gDebugGL)) log_glerror(__FILE__, __LINE__)
#endif

void clear_glerror();

// 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. There are a collection of helper
	classes below that define groups of enables/disables and 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 blend(GL_BLEND);
	renderHUD();
	LLGLDisable blend(GL_BLEND);

	// CORRECT USAGE
	{
		LLGLEnable blend(GL_BLEND);
		renderHUD();
	}

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

	{
		LLGLEnable blend(blend_hud ? GL_BLEND : 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
{
protected:
	LOG_CLASS(LLGLState);

public:
	static void initClass();
	static void restoreGL();

	static void dumpStates();
	
	static void checkStates(const std::string& msg = LLStringUtil::null,
							S32 line = -1);

#if 0	// Not used, but kept in source, just in case... HB
	// Really should not be needed.
	static void resetTextureStates();
#endif

protected:
	typedef fast_hmap<U32, GLboolean> state_map_t;
	static state_map_t sStateMap;

public:
	enum { CURRENT_STATE = -2 };
	LLGLState(U32 state, S32 enabled = CURRENT_STATE);
	virtual ~LLGLState();

	void setEnabled(S32 enabled);
	LL_INLINE void enable()						{ setEnabled(GL_TRUE); }
	LL_INLINE void disable()					{ setEnabled(GL_FALSE); }

protected:
	U32			mState;
	S32			mWasEnabled;
	S32			mIsEnabled;
};

// Helper define, to log the filename and line number of the checkStates()
// call, whenever an error is detected. Unless you got a specific message to
// pass on error, use this macro instead of LLGLState::checkStates(). HB
#define LL_GL_CHECK_STATES	LLGLState::checkStates(__FILE__, __LINE__)

class LLGLEnable : public LLGLState
{
public:
	LL_INLINE LLGLEnable(U32 state)
	:	LLGLState(state, GL_TRUE)
	{
	}
};

class LLGLDisable : public LLGLState
{
public:
	LL_INLINE LLGLDisable(U32 state)
	:	LLGLState(state, GL_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.
*/

class alignas(16) LLGLUserClipPlane
{
public:
	LLGLUserClipPlane(const LLPlane& plane, const LLMatrix4a& modelview,
					  const LLMatrix4a& projection, bool apply = true);
	~LLGLUserClipPlane();

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

private:
	LLMatrix4a	mProjection;
	LLMatrix4a	mModelview;

	bool		mApply;
};

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

  Restores projection matrix on destruction.
  Saves/restores matrix mode around projection manipulation.
  Does not stack.
*/

class LLGLSquashToFarClip
{
public:
	LLGLSquashToFarClip(U32 layer = 0);
	~LLGLSquashToFarClip();
};

/*
	Interface for objects that need periodic GL updates applied to them.
	Used to synchronize GL updates with GL thread.
*/

class LLGLUpdate
{
public:
	LLGLUpdate()
	:	mInQ(false)
	{
	}

	virtual ~LLGLUpdate()
	{
		if (mInQ)
		{
			std::list<LLGLUpdate*>::iterator end = sGLQ.end();
			std::list<LLGLUpdate*>::iterator iter = std::find(sGLQ.begin(),
															  end,
															  this);
			if (iter != end)
			{
				sGLQ.erase(iter);
			}
		}
	}

	virtual void updateGL() = 0;

public:
	static std::list<LLGLUpdate*> sGLQ;

	bool mInQ;
};

///////////////////////////////////////////////////////////////////////////////
// Formerly in llglstates.h, but since that header was #included by this one...
///////////////////////////////////////////////////////////////////////////////

class LLGLDepthTest
{
protected:
	LOG_CLASS(LLGLDepthTest);

public:
	// Enabled by default
	// Note: the new 'ignored' allows (when 'true' to make this class a no-
	// operation, so to simplify the dual renderer code. HB
	LLGLDepthTest(GLboolean depth_enabled, GLboolean write_enabled = GL_TRUE,
				  U32 depth_func = GL_LEQUAL, bool ignored = false);

	~LLGLDepthTest();

	void checkState();

public:
	U32					mPrevDepthFunc;
	GLboolean			mPrevDepthEnabled;
	GLboolean			mPrevWriteEnabled;

private:
	bool				mIgnored;

	static U32			sDepthFunc;		// defaults to GL_LESS
	static GLboolean	sDepthEnabled;	// defaults to GL_FALSE
	static GLboolean	sWriteEnabled;	// defaults to GL_TRUE
};

class LLGLSDefault
{
public:
	LLGLSDefault()
	:	// Disable
		mBlend(GL_BLEND),
		mCullFace(GL_CULL_FACE)
	{
	}

protected:
	LLGLDisable	mBlend;
	LLGLDisable	mCullFace;
};

class LLGLSObjectSelect
{
public:
	LLGLSObjectSelect()
	:	mBlend(GL_BLEND),
		mCullFace(GL_CULL_FACE)
	{
	}

protected:
	LLGLDisable	mBlend;
	LLGLEnable	mCullFace;
};

class LLGLSUIDefault
{
public:
	LLGLSUIDefault()
	:	mBlend(GL_BLEND),
		mCullFace(GL_CULL_FACE),
		mDepthTest(GL_FALSE, GL_TRUE, GL_LEQUAL),
		mMSAA(GL_MULTISAMPLE)
	{
	}

protected:
	LLGLEnable		mBlend;
	LLGLDisable		mCullFace;
	LLGLDepthTest	mDepthTest;
	LLGLDisable		mMSAA;
};

class LLGLSPipeline
{
public:
	LLGLSPipeline()
	:	mCullFace(GL_CULL_FACE),
		mDepthTest(GL_TRUE, GL_TRUE, GL_LEQUAL)
	{
	}

protected:
	LLGLEnable		mCullFace;
	LLGLDepthTest	mDepthTest;
};

class LLGLSPipelineAlpha // : public LLGLSPipeline
{
public:
	LLGLSPipelineAlpha()
	:	mBlend(GL_BLEND)
	{
	}

protected:
	LLGLEnable mBlend;
};

class LLGLSPipelineSelection
{
public:
	LLGLSPipelineSelection()
	:	mCullFace(GL_CULL_FACE)
	{
	}

protected:
	LLGLDisable mCullFace;
};

class LLGLSPipelineSkyBox
{
public:
	LLGLSPipelineSkyBox();
	virtual ~LLGLSPipelineSkyBox() = default;

protected:
	LLGLDisable			mCullFace;
	LLGLSquashToFarClip	mSquashClip;
};

class LLGLSPipelineDepthTestSkyBox : public LLGLSPipelineSkyBox
{
public:
	LLGLSPipelineDepthTestSkyBox(GLboolean depth_test, GLboolean depth_write);

public:
	LLGLDepthTest mDepth;
};

class LLGLSPipelineBlendSkyBox : public LLGLSPipelineDepthTestSkyBox
{
public:
	LLGLSPipelineBlendSkyBox(GLboolean depth_test, GLboolean depth_write);

public:
	LLGLEnable mBlend;
};

class LLGLSTracker
{
public:
	LLGLSTracker()
	:	mCullFace(GL_CULL_FACE),
		mBlend(GL_BLEND)
	{
	}

protected:
	LLGLEnable mCullFace;
	LLGLEnable mBlend;
};

class LLGLSSpecular
{
public:
	LLGLSSpecular(const LLColor4& color, F32 shininess)
	{
		mShininess = shininess;
		if (mShininess > 0.f)
		{
			glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, color.mV);
			S32 shiny = (S32)(shininess * 128.f);
			shiny = llclamp(shiny, 0, 128);
			glMateriali(GL_FRONT_AND_BACK, GL_SHININESS, shiny);
		}
	}

	~LLGLSSpecular()
	{
		if (mShininess > 0.f)
		{
			glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR,
						 LLColor4::transparent.mV);
			glMateriali(GL_FRONT_AND_BACK, GL_SHININESS, 0);
		}
	}

public:
	F32 mShininess;
};

///////////////////////////////////////////////////////////////////////////////

const std::string getGLErrorString(U32 error);

#endif // LL_LLGL_H