Aerofoil/AerofoilSDL/GpDisplayDriver_SDL_GL2.cpp

#include "IGpDisplayDriver.h"

#include "GpApplicationName.h"
#include "GpComPtr.h"
#include "GpFiber_SDL.h"
#include "GpDisplayDriverProperties.h"
#include "GpSystemServices_Win32.h"
#include "GpWindows.h"	// TODO: Remove
#include "GpVOSEvent.h"
#include "GpRingBuffer.h"
#include "IGpCursor.h"
#include "IGpDisplayDriverSurface.h"
#include "IGpLogDriver.h"
#include "IGpPrefsHandler.h"
#include "IGpVOSEventQueue.h"

#include "SDL_opengl.h"
#include "SDL_video.h"

#include <stdlib.h>
#include <new>
#include <assert.h>

#include <chrono>
#include <numeric>
#include <vector>


#pragma push_macro("LoadCursor")
#ifdef LoadCursor
#undef LoadCursor
#endif

#define GP_GL_IS_OPENGL_4_CONTEXT	0

class GpDisplayDriver_SDL_GL2;

static GpDisplayDriverSurfaceEffects gs_defaultEffects;

namespace GpBinarizedShaders
{
	extern const char *g_drawQuadV_GL2;

	extern const char *g_drawQuadPaletteP_GL2;
	extern const char *g_drawQuadRGBP_GL2;
	extern const char *g_drawQuad15BitP_GL2;

	extern const char *g_drawQuadPaletteICCP_GL2;
	extern const char *g_drawQuadRGBICCP_GL2;
	extern const char *g_drawQuad15BitICCP_GL2;

	extern const char *g_scaleQuadP_GL2;
}

struct GpGLFunctions
{
	typedef void (GLAPIENTRYP PFNGLCLEARPROC)(GLbitfield mask);
	typedef void (GLAPIENTRYP PFNGLCLEARCOLORPROC)(GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha);
	typedef void (GLAPIENTRYP PFNGLVIEWPORTPROC)(GLint x, GLint y, GLsizei width, GLsizei height);
	typedef void (GLAPIENTRYP PFNGLDRAWELEMENTSPROC)(GLenum mode, GLsizei count, GLenum type, const GLvoid *indices);
	typedef void (GLAPIENTRYP PFNGLBINDTEXTUREPROC)(GLenum target, GLuint texture);
	typedef void (GLAPIENTRYP PFNGLGENTEXTURESPROC)(GLsizei n, GLuint *textures);
	typedef void (GLAPIENTRYP PFNGLDELETETEXTURESPROC)(GLsizei n, GLuint *textures);
	typedef void (GLAPIENTRYP PFNGLTEXIMAGE2DPROC)(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels);
	typedef void (GLAPIENTRYP PFNGLTEXSUBIMAGE2DPROC)(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels);
	typedef void (GLAPIENTRYP PFNGLPIXELSTOREIPROC)(GLenum pname, GLint param);
	typedef void (GLAPIENTRYP PFNGLTEXPARAMETERIPROC)(GLenum target, GLenum pname, GLint param);
	typedef GLenum (GLAPIENTRYP PFNGLGETERRORPROC)();

	PFNGLCLEARPROC Clear;
	PFNGLCLEARCOLORPROC ClearColor;

	PFNGLVIEWPORTPROC Viewport;

	PFNGLGENFRAMEBUFFERSPROC GenFramebuffers;
	PFNGLBINDFRAMEBUFFERPROC BindFramebuffer;
	PFNGLFRAMEBUFFERTEXTURE2DPROC FramebufferTexture2D;
	PFNGLCHECKFRAMEBUFFERSTATUSPROC CheckFramebufferStatus;
	PFNGLDELETEFRAMEBUFFERSPROC DeleteFramebuffers;

	PFNGLGENBUFFERSPROC GenBuffers;
	PFNGLBUFFERDATAPROC BufferData;
	PFNGLMAPBUFFERPROC MapBuffer;
	PFNGLBINDBUFFERPROC BindBuffer;
	PFNGLDELETEBUFFERSPROC DeleteBuffers;

	PFNGLCREATEPROGRAMPROC CreateProgram;
	PFNGLDELETEPROGRAMPROC DeleteProgram;
	PFNGLLINKPROGRAMPROC LinkProgram;
	PFNGLUSEPROGRAMPROC UseProgram;
	PFNGLGETPROGRAMIVPROC GetProgramiv;
	PFNGLGETPROGRAMINFOLOGPROC GetProgramInfoLog;
	PFNGLGETUNIFORMLOCATIONPROC GetUniformLocation;
	PFNGLGETATTRIBLOCATIONPROC GetAttribLocation;
	PFNGLUNIFORM4FVPROC Uniform4fv;
	PFNGLUNIFORM2FVPROC Uniform2fv;
	PFNGLUNIFORM1FVPROC Uniform1fv;
	PFNGLVERTEXATTRIBPOINTERPROC VertexAttribPointer;

	PFNGLENABLEVERTEXATTRIBARRAYPROC EnableVertexAttribArray;
	PFNGLDISABLEVERTEXATTRIBARRAYPROC DisableVertexAttribArray;

#if GP_GL_IS_OPENGL_4_CONTEXT
	PFNGLGENVERTEXARRAYSPROC GenVertexArrays;
	PFNGLDELETEVERTEXARRAYSPROC DeleteVertexArrays;
	PFNGLBINDVERTEXARRAYPROC BindVertexArray;
#endif

	PFNGLCREATESHADERPROC CreateShader;
	PFNGLCOMPILESHADERPROC CompileShader;
	PFNGLGETSHADERIVPROC GetShaderiv;
	PFNGLGETSHADERINFOLOGPROC GetShaderInfoLog;
	PFNGLATTACHSHADERPROC AttachShader;
	PFNGLSHADERSOURCEPROC ShaderSource;
	PFNGLDELETESHADERPROC DeleteShader;

	PFNGLDRAWELEMENTSPROC DrawElements;

	PFNGLACTIVETEXTUREPROC ActiveTexture;
	PFNGLBINDTEXTUREPROC BindTexture;
	PFNGLTEXPARAMETERIPROC TexParameteri;
	PFNGLTEXIMAGE2DPROC TexImage2D;
	PFNGLTEXSUBIMAGE2DPROC TexSubImage2D;
	PFNGLPIXELSTOREIPROC PixelStorei;
	PFNGLUNIFORM1IPROC Uniform1i;

	PFNGLGENTEXTURESPROC GenTextures;
	PFNGLDELETETEXTURESPROC DeleteTextures;

	PFNGLGETERRORPROC GetError;

	bool LookUpFunctions();
};

class GpGLObject
{
public:
	explicit GpGLObject();

	void AddRef();
	void Release();

protected:
	void InitDriver(GpDisplayDriver_SDL_GL2 *driver, const GpGLFunctions *gl);
	virtual void Destroy() = 0;

	GpDisplayDriver_SDL_GL2 *m_driver;
	const GpGLFunctions *m_gl;
	unsigned int m_count;
};


GpGLObject::GpGLObject()
	: m_count(0)
	, m_driver(nullptr)
{
}

void GpGLObject::AddRef()
{
	++m_count;
}

void GpGLObject::Release()
{
	unsigned int count = m_count;
	if (count == 1)
	{
		this->Destroy();
		return;
	}
	else
		m_count = count - 1;
}

void GpGLObject::InitDriver(GpDisplayDriver_SDL_GL2 *driver, const GpGLFunctions *gl)
{
	m_driver = driver;
	m_gl = gl;
}


template<class T>
class GpGLObjectImpl : public GpGLObject
{
public:
	static T *Create(GpDisplayDriver_SDL_GL2 *driver);

protected:
	virtual bool Init() = 0;
	void Destroy() final override;
};

template<class T>
void GpGLObjectImpl<T>::Destroy()
{
	T *self = static_cast<T*>(this);
	self->~T();
	free(self);
}

class GpGLRenderTargetView final : public GpGLObjectImpl<GpGLRenderTargetView>
{
public:
	GpGLRenderTargetView();
	~GpGLRenderTargetView();

	bool Init() override;
	GLuint GetID() const;

private:
	GLuint m_id;
};


GpGLRenderTargetView::GpGLRenderTargetView()
	: m_id(0)
{
}

GpGLRenderTargetView::~GpGLRenderTargetView()
{
	if (m_id)
		m_gl->DeleteFramebuffers(1, &m_id);
}

bool GpGLRenderTargetView::Init()
{
	m_gl->GenFramebuffers(1, &m_id);

	return m_id != 0;
}

GLuint GpGLRenderTargetView::GetID() const
{
	return m_id;
}

class GpGLTexture final : public GpGLObjectImpl<GpGLTexture>
{
public:
	GpGLTexture();
	~GpGLTexture();

	bool Init() override;
	GLuint GetID() const;

private:
	GLuint m_id;
};


GpGLTexture::GpGLTexture()
	: m_id(0)
{
}

GpGLTexture::~GpGLTexture()
{
	if (m_gl)
		m_gl->DeleteTextures(1, &m_id);
}

bool GpGLTexture::Init()
{
	m_gl->GenTextures(1, &m_id);

	return m_id != 0;
}

GLuint GpGLTexture::GetID() const
{
	return m_id;
}


class GpGLBuffer final : public GpGLObjectImpl<GpGLBuffer>
{
public:
	GpGLBuffer();
	~GpGLBuffer();

	bool Init() override;
	GLuint GetID() const;

private:
	GLuint m_id;
};

GpGLBuffer::GpGLBuffer()
	: m_id(0)
{
}

GpGLBuffer::~GpGLBuffer()
{
	if (m_gl)
		m_gl->DeleteBuffers(1, &m_id);
}

bool GpGLBuffer::Init()
{
	m_gl->GenBuffers(1, &m_id);

	return m_id != 0;
}

GLuint GpGLBuffer::GetID() const
{
	return m_id;
}


struct GpGLVertexArraySpec
{
	const GpGLBuffer *m_buffer;
	GLuint m_index;
	GLint m_size;
	GLenum m_type;
	GLboolean m_normalized;
	GLsizei m_stride;
	GLsizei m_offset;
};

#if GP_GL_IS_OPENGL_4_CONTEXT

class GpGLVertexArray final : public GpGLObjectImpl<GpGLVertexArray>
{
public:
	GpGLVertexArray();
	~GpGLVertexArray();

	bool Init() override;
	GLuint GetID() const;

	bool InitWithSpecs(const GpGLVertexArraySpec *specs, size_t numSpecs);
	void Activate(const GLint *locations);
	void Deactivate(const GLint *locations);

private:
	GLuint m_id;
};


GpGLVertexArray::GpGLVertexArray()
	: m_id(0)
{
}

GpGLVertexArray::~GpGLVertexArray()
{
	if (m_id)
		m_gl->DeleteVertexArrays(1, &m_id);
}

bool GpGLVertexArray::Init()
{
	m_gl->GenVertexArrays(1, &m_id);
	return m_id != 0;
}

GLuint GpGLVertexArray::GetID() const
{
	return m_id;
}


bool GpGLVertexArray::InitWithSpecs(const GpGLVertexArraySpec *specs, size_t numSpecs)
{
	m_gl->BindVertexArray(m_id);
	for (size_t i = 0; i < numSpecs; i++)
	{
		const GpGLVertexArraySpec &spec = specs[i];
		m_gl->BindBuffer(GL_ARRAY_BUFFER, spec.m_buffer->GetID());
		m_gl->VertexAttribPointer(spec.m_index, spec.m_size, spec.m_type, spec.m_normalized, spec.m_stride, static_cast<const char*>(nullptr) + spec.m_offset);
		m_gl->EnableVertexAttribArray(spec.m_index);
		m_gl->BindBuffer(GL_ARRAY_BUFFER, 0);
	}
	m_gl->BindVertexArray(0);

	return true;
}

void GpGLVertexArray::Activate(const GLint *locations)
{
	m_gl->BindVertexArray(m_id);
}

void GpGLVertexArray::Deactivate(const GLint *locations)
{
	m_gl->BindVertexArray(0);
}
#else
class GpGLVertexArray final : public GpGLObjectImpl<GpGLVertexArray>
{
public:
	GpGLVertexArray();
	~GpGLVertexArray();

	bool Init() override;

	bool InitWithSpecs(const GpGLVertexArraySpec *specs, size_t numSpecs);
	void Activate(const GLint *locations);
	void Deactivate(const GLint *locations);

private:
	GpGLVertexArraySpec *m_specs;
	size_t m_numSpecs;
};


GpGLVertexArray::GpGLVertexArray()
	: m_specs(nullptr)
	, m_numSpecs(0)
{
}

GpGLVertexArray::~GpGLVertexArray()
{
	if (m_specs)
		free(m_specs);
}

bool GpGLVertexArray::Init()
{
	return true;
}

bool GpGLVertexArray::InitWithSpecs(const GpGLVertexArraySpec *specs, size_t numSpecs)
{
	m_specs = static_cast<GpGLVertexArraySpec*>(malloc(sizeof(GpGLVertexArraySpec) * numSpecs));
	if (!m_specs)
		return false;

	for (size_t i = 0; i < numSpecs; i++)
		m_specs[i] = specs[i];

	m_numSpecs = numSpecs;
}

void GpGLVertexArray::Activate(const GLint *locations)
{
	size_t numSpecs = m_numSpecs;
	for (size_t i = 0; i < numSpecs; i++)
	{
		if (locations[i] < 0)
			continue;

		const GpGLVertexArraySpec &spec = m_specs[i];
		m_gl->BindBuffer(GL_ARRAY_BUFFER, spec.m_buffer->GetID());
		m_gl->VertexAttribPointer(locations[i], spec.m_size, spec.m_type, spec.m_normalized, spec.m_stride, static_cast<const char*>(nullptr) + spec.m_offset);
		m_gl->EnableVertexAttribArray(locations[i]);
		m_gl->BindBuffer(GL_ARRAY_BUFFER, 0);
	}
}

void GpGLVertexArray::Deactivate(const GLint *locations)
{
	size_t numSpecs = m_numSpecs;
	for (size_t i = 0; i < numSpecs; i++)
	{
		if (locations[i] < 0)
			continue;

		m_gl->DisableVertexAttribArray(locations[i]);
	}
}
#endif

class GpGLProgram final : public GpGLObjectImpl<GpGLProgram>
{
public:
	GpGLProgram();
	~GpGLProgram();

	bool Init() override;
	GLuint GetID() const;

private:
	GLuint m_id;
};

GpGLProgram::GpGLProgram()
	: m_id(0)
{
}

GpGLProgram::~GpGLProgram()
{
	if (m_id)
		m_gl->DeleteProgram(m_id);
}

bool GpGLProgram::Init()
{
	m_id = m_gl->CreateProgram();

	return m_id != 0;
}

GLuint GpGLProgram::GetID() const
{
	return m_id;
}

template<GLuint TShaderType>
class GpGLShader final : public GpGLObjectImpl<GpGLShader<TShaderType> >
{
public:
	GpGLShader();
	~GpGLShader();

	bool Init() override;
	GLuint GetID() const;

private:
	GLuint m_id;
};

template<GLuint TShaderType>
GpGLShader<TShaderType>::GpGLShader()
	: m_id(0)
{
}

template<GLuint TShaderType>
GpGLShader<TShaderType>::~GpGLShader()
{
	if (m_id != 0)
		this->m_gl->DeleteShader(m_id);
}

template<GLuint TShaderType>
bool GpGLShader<TShaderType>::Init()
{
	m_id = this->m_gl->CreateShader(TShaderType);
	return m_id != 0;
}

template<GLuint TShaderType>
GLuint GpGLShader<TShaderType>::GetID() const
{
	return m_id;
}

class GpDisplayDriverSurface_GL2 : public IGpDisplayDriverSurface
{
public:
	GpDisplayDriverSurface_GL2(GpDisplayDriver_SDL_GL2 *driver, size_t width, size_t height, size_t pitch, GpGLTexture *texture, GpPixelFormat_t pixelFormat);
	~GpDisplayDriverSurface_GL2();

	static GpDisplayDriverSurface_GL2 *Create(GpDisplayDriver_SDL_GL2 *driver, size_t width, size_t height, size_t pitch, GpPixelFormat_t pixelFormat);

	void Upload(const void *data, size_t x, size_t y, size_t width, size_t height, size_t pitch);
	void UploadEntire(const void *data, size_t pitch);
	void Destroy();

	size_t GetImageWidth() const;
	size_t GetPaddedTextureWidth() const;
	size_t GetHeight() const;
	GpPixelFormat_t GetPixelFormat() const;
	GpGLTexture *GetTexture() const;

private:
	bool Init();
	GLenum ResolveGLFormat() const;
	GLenum ResolveGLInternalFormat() const;
	GLenum ResolveGLType() const;

	GpComPtr<GpGLTexture> m_texture;
	const GpGLFunctions *m_gl;
	GpPixelFormat_t m_pixelFormat;
	size_t m_imageWidth;
	size_t m_paddedTextureWidth;
	size_t m_pitch;
	size_t m_height;
};

class GpCursor_SDL2 final : public IGpCursor
{
public:
	void Destroy() override { delete this; }
};

class GpDisplayDriver_SDL_GL2 final : public IGpDisplayDriver, public IGpPrefsHandler
{
public:
	explicit GpDisplayDriver_SDL_GL2(const GpDisplayDriverProperties &properties);
	~GpDisplayDriver_SDL_GL2();

	bool Init();

	void Run() override;
	void Shutdown() override;
	void GetDisplayResolution(unsigned int *width, unsigned int *height) override;
	IGpDisplayDriverSurface *CreateSurface(size_t width, size_t height, size_t pitch, GpPixelFormat_t pixelFormat) override;
	void DrawSurface(IGpDisplayDriverSurface *surface, int32_t x, int32_t y, size_t width, size_t height, const GpDisplayDriverSurfaceEffects *effects) override;
	IGpCursor *LoadCursor(bool isColor, int cursorID) override;
	void SetCursor(IGpCursor *cursor) override;
	void SetStandardCursor(EGpStandardCursor_t standardCursor) override;
	void UpdatePalette(const void *paletteData) override;
	void SetBackgroundColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a) override;
	void SetBackgroundDarkenEffect(bool isDark) override;
	void SetUseICCProfile(bool useICCProfile) override;
	void RequestToggleFullScreen(uint32_t timestamp) override;
	void RequestResetVirtualResolution() override;
	bool IsFullScreen() const override;
	const GpDisplayDriverProperties &GetProperties() const override;
	IGpPrefsHandler *GetPrefsHandler() const override;

	void ApplyPrefs(const void *identifier, size_t identifierSize, const void *contents, size_t contentsSize, uint32_t version) override;
	bool SavePrefs(void *context, WritePrefsFunc_t writeFunc) override;

	const GpGLFunctions *GetGLFunctions() const;

	template<GLuint TShaderType> GpComPtr<GpGLShader<TShaderType> > CreateShader(const char *shaderSrc);

private:
	struct DrawQuadPixelFloatConstants
	{
		float m_modulation[4];

		float m_flickerAxis[2];
		float m_flickerStart;
		float m_flickerEnd;

		float m_desaturation;
		float m_unused[3];
	};

	struct CompactedPresentHistoryItem
	{
		std::chrono::time_point<std::chrono::high_resolution_clock>::duration m_timestamp;
		unsigned int m_numFrames;
	};

	void StartOpenGLForWindow(IGpLogDriver *logger);
	bool InitResources(uint32_t virtualWidth, uint32_t virtualHeight);

	void BecomeFullScreen();
	void BecomeWindowed();

	bool ResizeOpenGLWindow(uint32_t &windowWidth, uint32_t &windowHeight, uint32_t desiredWidth, uint32_t desiredHeight, IGpLogDriver *logger);
	bool InitBackBuffer(uint32_t width, uint32_t height);

	void ScaleVirtualScreen();

	GpDisplayDriverTickStatus_t PresentFrameAndSync();

	GpGLFunctions m_gl;
	GpDisplayDriverProperties m_properties;

	GpComPtr<GpGLRenderTargetView> m_virtualScreenTextureRTV;
	GpComPtr<GpGLTexture> m_virtualScreenTexture;

	GpComPtr<GpGLVertexArray> m_quadVertexArray;
	GpComPtr<GpGLBuffer> m_quadVertexBufferKeepalive;
	GpComPtr<GpGLBuffer> m_quadIndexBuffer;

	GpComPtr<GpGLTexture> m_paletteTexture;

	struct DrawQuadProgram
	{
		GpComPtr<GpGLProgram> m_program;
		GLint m_vertexNDCOriginAndDimensionsLocation;
		GLint m_vertexSurfaceDimensionsLocation;
		GLint m_vertexPosUVLocation;
		GLint m_pixelModulationLocation;
		GLint m_pixelFlickerAxisLocation;
		GLint m_pixelFlickerStartThresholdLocation;
		GLint m_pixelFlickerEndThresholdLocation;
		GLint m_pixelDesaturationLocation;
		GLint m_pixelSurfaceTextureLocation;
		GLint m_pixelPaletteTextureLocation;

		bool Link(GpDisplayDriver_SDL_GL2 *driver, const GpGLShader<GL_VERTEX_SHADER> *vertexShader, const GpGLShader<GL_FRAGMENT_SHADER> *pixelShader);
	};

	struct ScaleQuadProgram
	{
		GpComPtr<GpGLProgram> m_program;
		GLint m_vertexNDCOriginAndDimensionsLocation;
		GLint m_vertexSurfaceDimensionsLocation;
		GLint m_pixelDXDYDimensionsLocation;
		GLint m_vertexPosUVLocation;
		GLint m_pixelSurfaceTextureLocation;
		GLint m_pixelPaletteTextureLocation;

		bool Link(GpDisplayDriver_SDL_GL2 *driver, const GpGLShader<GL_VERTEX_SHADER> *vertexShader, const GpGLShader<GL_FRAGMENT_SHADER> *pixelShader);
	};

	ScaleQuadProgram m_scaleQuadProgram;

	DrawQuadProgram m_drawQuadPaletteProgram;
	DrawQuadProgram m_drawQuadRGBProgram;
	DrawQuadProgram m_drawQuad15BitProgram;
	DrawQuadProgram m_drawQuadPaletteICCProgram;
	DrawQuadProgram m_drawQuadRGBICCProgram;
	DrawQuadProgram m_drawQuad15BitICCProgram;

	SDL_Window *m_window;
	SDL_GLContext m_glContext;

	UINT m_expectedSyncDelta;
	bool m_isResettingSwapChain;

	bool m_isFullScreen;
	bool m_isFullScreenDesired;
	bool m_isResolutionResetDesired;
	int m_windowModeRevertX;
	int m_windowModeRevertY;
	int m_windowModeRevertWidth;
	int m_windowModeRevertHeight;
	uint32_t m_lastFullScreenToggleTimeStamp;

	std::chrono::high_resolution_clock::duration m_frameTimeAccumulated;
	std::chrono::high_resolution_clock::duration m_frameTimeSliceSize;

	uint32_t m_windowWidthPhysical;	// Physical resolution is the resolution of the actual window
	uint32_t m_windowHeightPhysical;
	uint32_t m_windowWidthVirtual;		// Virtual resolution is the resolution reported to the game
	uint32_t m_windowHeightVirtual;
	float m_pixelScaleX;
	float m_pixelScaleY;

	IGpCursor *m_activeCursor;
	IGpCursor *m_pendingCursor;
	EGpStandardCursor_t m_currentStandardCursor;
	EGpStandardCursor_t m_pendingStandardCursor;
	bool m_mouseIsInClientArea;

	IGpFiber *m_vosFiber;
	PortabilityLayer::HostThreadEvent *m_vosEvent;
	GpWindowsGlobals *m_osGlobals;

	HCURSOR m_arrowCursor;
	HCURSOR m_waitCursor;
	HCURSOR m_ibeamCursor;

	float m_bgColor[4];
	bool m_bgIsDark;

	bool m_useICCProfile;

	std::chrono::time_point<std::chrono::high_resolution_clock>::duration m_syncTimeBase;
	GpRingBuffer<CompactedPresentHistoryItem, 60> m_presentHistory;
};


GpDisplayDriverSurface_GL2::GpDisplayDriverSurface_GL2(GpDisplayDriver_SDL_GL2 *driver, size_t width, size_t height, size_t pitch, GpGLTexture *texture, GpPixelFormat_t pixelFormat)
	: m_gl(driver->GetGLFunctions())
	, m_texture(texture)
	, m_pixelFormat(pixelFormat)
	, m_imageWidth(width)
	, m_paddedTextureWidth(0)
	, m_height(height)
	, m_pitch(pitch)
{
	size_t paddingPixels = 0;

	switch (pixelFormat)
	{
	case GpPixelFormats::kBW1:
	case GpPixelFormats::k8BitStandard:
	case GpPixelFormats::k8BitCustom:
		paddingPixels = pitch - width;
		break;
	case GpPixelFormats::kRGB555:
		assert(pitch % 2 == 0);
		paddingPixels = pitch / 2 - width;
		break;
	case GpPixelFormats::kRGB24:
		assert(pitch % 3 == 0);
		paddingPixels = pitch / 3 - width;
		break;
	case GpPixelFormats::kRGB32:
		assert(pitch % 4 == 0);
		paddingPixels = pitch / 4 - width;
		break;
	}

	m_paddedTextureWidth = width + paddingPixels;
}

GpDisplayDriverSurface_GL2::~GpDisplayDriverSurface_GL2()
{
}

GpDisplayDriverSurface_GL2 *GpDisplayDriverSurface_GL2::Create(GpDisplayDriver_SDL_GL2 *driver, size_t width, size_t height, size_t pitch, GpPixelFormat_t pixelFormat)
{
	GpComPtr<GpGLTexture> texture = GpComPtr<GpGLTexture>(GpGLTexture::Create(driver));
	if (!texture)
		return nullptr;

	GpDisplayDriverSurface_GL2 *surface = static_cast<GpDisplayDriverSurface_GL2*>(malloc(sizeof(GpDisplayDriverSurface_GL2)));
	if (!surface)
		return nullptr;

	new (surface) GpDisplayDriverSurface_GL2(driver, width, height, pitch, texture, pixelFormat);
	if (!surface->Init())
	{
		surface->Destroy();
		return nullptr;
	}

	return surface;
}

void GpDisplayDriverSurface_GL2::Upload(const void *data, size_t x, size_t y, size_t width, size_t height, size_t pitch)
{
	m_gl->BindTexture(GL_TEXTURE_2D, m_texture->GetID());
	m_gl->TexSubImage2D(GL_TEXTURE_2D, 0, x, y, width, height, ResolveGLFormat(), ResolveGLType(), data);
	m_gl->BindTexture(GL_TEXTURE_2D, 0);
}

void GpDisplayDriverSurface_GL2::UploadEntire(const void *data, size_t pitch)
{
	assert(pitch == m_pitch);

	GLenum preError = m_gl->GetError();
	GLenum preError2 = m_gl->GetError();

	const GLint internalFormat = ResolveGLInternalFormat();
	const GLenum glFormat = ResolveGLFormat();
	const GLenum glType = ResolveGLType();

	m_gl->BindTexture(GL_TEXTURE_2D, m_texture->GetID());
	m_gl->TexImage2D(GL_TEXTURE_2D, 0, internalFormat, m_paddedTextureWidth, m_height, 0, glFormat, glType, data);
	m_gl->BindTexture(GL_TEXTURE_2D, 0);

	GLenum postError = m_gl->GetError();

	int n = 0;
}

void GpDisplayDriverSurface_GL2::Destroy()
{
	this->~GpDisplayDriverSurface_GL2();
	free(this);
}

size_t GpDisplayDriverSurface_GL2::GetImageWidth() const
{
	return m_imageWidth;
}

size_t GpDisplayDriverSurface_GL2::GetPaddedTextureWidth() const
{
	return m_paddedTextureWidth;
}

size_t GpDisplayDriverSurface_GL2::GetHeight() const
{
	return m_height;
}

GpPixelFormat_t GpDisplayDriverSurface_GL2::GetPixelFormat() const
{
	return m_pixelFormat;
}

GpGLTexture *GpDisplayDriverSurface_GL2::GetTexture() const
{
	return m_texture;
}


bool GpDisplayDriverSurface_GL2::Init()
{
	m_gl->BindTexture(GL_TEXTURE_2D, m_texture->GetID());
	m_gl->PixelStorei(GL_UNPACK_ALIGNMENT, 1);
	m_gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	m_gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	m_gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	m_gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	m_gl->TexImage2D(GL_TEXTURE_2D, 0, ResolveGLInternalFormat(), m_paddedTextureWidth, m_height, 0, ResolveGLFormat(), ResolveGLType(), nullptr);
	m_gl->BindTexture(GL_TEXTURE_2D, 0);

	return true;
}

GLenum GpDisplayDriverSurface_GL2::ResolveGLFormat() const
{
	switch (m_pixelFormat)
	{
	case GpPixelFormats::k8BitCustom:
	case GpPixelFormats::k8BitStandard:
	case GpPixelFormats::kBW1:
		return GL_RED;
	case GpPixelFormats::kRGB24:
	case GpPixelFormats::kRGB555:
		return GL_RGB;
	case GpPixelFormats::kRGB32:
		return GL_RGBA;
	default:
		return GL_RGBA;
	}
}

GLenum GpDisplayDriverSurface_GL2::ResolveGLInternalFormat() const
{
	switch (m_pixelFormat)
	{
	case GpPixelFormats::k8BitCustom:
	case GpPixelFormats::k8BitStandard:
	case GpPixelFormats::kBW1:
		return GL_R8;
	case GpPixelFormats::kRGB24:
		return GL_RGB8;
	case GpPixelFormats::kRGB555:
		return GL_RGB5;
	case GpPixelFormats::kRGB32:
		return GL_RGBA8;
	default:
		return GL_RGBA8;
	}
}

GLenum GpDisplayDriverSurface_GL2::ResolveGLType() const
{
	switch (m_pixelFormat)
	{
	case GpPixelFormats::k8BitCustom:
	case GpPixelFormats::k8BitStandard:
	case GpPixelFormats::kBW1:
		return GL_UNSIGNED_BYTE;
	case GpPixelFormats::kRGB24:
		return GL_UNSIGNED_BYTE;
	case GpPixelFormats::kRGB555:
		return GL_UNSIGNED_SHORT_5_5_5_1;
	case GpPixelFormats::kRGB32:
		return GL_UNSIGNED_BYTE;
	default:
		return GL_UNSIGNED_BYTE;
	}
}


GpDisplayDriver_SDL_GL2::GpDisplayDriver_SDL_GL2(const GpDisplayDriverProperties &properties)
	: m_window(nullptr)
	, m_frameTimeAccumulated(std::chrono::high_resolution_clock::duration::zero())
	, m_frameTimeSliceSize(std::chrono::high_resolution_clock::duration::zero())
	, m_windowWidthPhysical(640)
	, m_windowHeightPhysical(480)
	, m_windowWidthVirtual(640)
	, m_windowHeightVirtual(480)
	, m_pixelScaleX(1.0f)
	, m_pixelScaleY(1.0f)
	, m_vosFiber(nullptr)
	, m_vosEvent(nullptr)
	, m_pendingCursor(nullptr)
	, m_activeCursor(nullptr)
	, m_currentStandardCursor(EGpStandardCursors::kArrow)
	, m_pendingStandardCursor(EGpStandardCursors::kArrow)
	, m_mouseIsInClientArea(false)
	, m_isFullScreen(false)
	, m_isFullScreenDesired(false)
	, m_isResolutionResetDesired(false)
	, m_windowModeRevertX(200)
	, m_windowModeRevertY(200)
	, m_windowModeRevertWidth(640)
	, m_windowModeRevertHeight(480)
	, m_lastFullScreenToggleTimeStamp(0)
	, m_bgIsDark(false)
	, m_useICCProfile(false)
	, m_osGlobals(static_cast<GpWindowsGlobals*>(properties.m_osGlobals))
	, m_properties(properties)
	, m_syncTimeBase(std::chrono::time_point<std::chrono::high_resolution_clock>::duration::zero())
{
	m_bgColor[0] = 0.f;
	m_bgColor[1] = 0.f;
	m_bgColor[2] = 0.f;
	m_bgColor[3] = 1.f;

	const intmax_t periodNum = std::chrono::high_resolution_clock::period::num;
	const intmax_t periodDen = std::chrono::high_resolution_clock::period::den;

	m_frameTimeSliceSize = std::chrono::high_resolution_clock::duration(periodDen * static_cast<intmax_t>(properties.m_frameTimeLockNumerator) / static_cast<intmax_t>(properties.m_frameTimeLockDenominator) / periodNum);
}

template<class T>
static bool LookupOpenGLFunction(T &target, const char *name)
{
	target = static_cast<T>(nullptr);
	void *proc = SDL_GL_GetProcAddress(name);
	if (proc)
	{
		target = static_cast<T>(proc);
		return true;
	}
	else
		return false;
}

#define LOOKUP_FUNC(func) do { if (!LookupOpenGLFunction(this->func, "gl" #func)) return false; } while(false)
			

bool GpGLFunctions::LookUpFunctions()
{
	LOOKUP_FUNC(Clear);
	LOOKUP_FUNC(ClearColor);

	LOOKUP_FUNC(Viewport);

	LOOKUP_FUNC(GenFramebuffers);
	LOOKUP_FUNC(BindFramebuffer);
	LOOKUP_FUNC(FramebufferTexture2D);
	LOOKUP_FUNC(CheckFramebufferStatus);
	LOOKUP_FUNC(DeleteFramebuffers);

	LOOKUP_FUNC(GenBuffers);
	LOOKUP_FUNC(BufferData);
	LOOKUP_FUNC(MapBuffer);
	LOOKUP_FUNC(BindBuffer);
	LOOKUP_FUNC(DeleteBuffers);

	LOOKUP_FUNC(CreateProgram);
	LOOKUP_FUNC(DeleteProgram);
	LOOKUP_FUNC(LinkProgram);
	LOOKUP_FUNC(UseProgram);
	LOOKUP_FUNC(GetProgramiv);
	LOOKUP_FUNC(GetProgramInfoLog);

	LOOKUP_FUNC(GetUniformLocation);
	LOOKUP_FUNC(GetAttribLocation);
	LOOKUP_FUNC(Uniform4fv);
	LOOKUP_FUNC(Uniform2fv);
	LOOKUP_FUNC(Uniform1fv);
	LOOKUP_FUNC(VertexAttribPointer);

	LOOKUP_FUNC(EnableVertexAttribArray);
	LOOKUP_FUNC(DisableVertexAttribArray);

#if GP_GL_IS_OPENGL_4_CONTEXT
	LOOKUP_FUNC(GenVertexArrays);
	LOOKUP_FUNC(DeleteVertexArrays);
	LOOKUP_FUNC(BindVertexArray);
#endif

	LOOKUP_FUNC(CreateShader);
	LOOKUP_FUNC(CompileShader);
	LOOKUP_FUNC(GetShaderiv);
	LOOKUP_FUNC(GetShaderInfoLog);
	LOOKUP_FUNC(AttachShader);
	LOOKUP_FUNC(ShaderSource);
	LOOKUP_FUNC(DeleteShader);

	LOOKUP_FUNC(DrawElements);

	LOOKUP_FUNC(ActiveTexture);
	LOOKUP_FUNC(BindTexture);
	LOOKUP_FUNC(TexParameteri);
	LOOKUP_FUNC(TexImage2D);
	LOOKUP_FUNC(TexSubImage2D);
	LOOKUP_FUNC(PixelStorei);
	LOOKUP_FUNC(Uniform1i);

	LOOKUP_FUNC(GenTextures);
	LOOKUP_FUNC(DeleteTextures);

	LOOKUP_FUNC(GetError);

	return true;
}

GpDisplayDriver_SDL_GL2::~GpDisplayDriver_SDL_GL2()
{
	SDL_DestroyWindow(m_window);
}

bool GpDisplayDriver_SDL_GL2::Init()
{
	return true;
}

void GpDisplayDriver_SDL_GL2::Run()
{
#if GP_GL_IS_OPENGL_4_CONTEXT
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
#else
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
#endif
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);

	IGpLogDriver *logger = m_properties.m_logger;

	m_vosEvent = GpSystemServices_Win32::GetInstance()->CreateThreadEvent(true, false);
	m_vosFiber = new GpFiber_SDL(nullptr, m_vosEvent);

	m_window = SDL_CreateWindow(GP_APPLICATION_NAME, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, m_windowWidthPhysical, m_windowHeightPhysical, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);

	StartOpenGLForWindow(logger);

	if (!m_gl.LookUpFunctions())
		return;

	InitResources(m_windowWidthVirtual, m_windowHeightVirtual);

	LARGE_INTEGER lastTimestamp;
	memset(&lastTimestamp, 0, sizeof(lastTimestamp));

	MSG msg;
	for (;;)
	{
		if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
		{
			DispatchMessage(&msg);

			{
				if (msg.message == WM_MOUSEMOVE)
				{
					if (!m_mouseIsInClientArea)
					{
						m_mouseIsInClientArea = true;

						TRACKMOUSEEVENT tme;
						ZeroMemory(&tme, sizeof(tme));

						tme.cbSize = sizeof(tme);
						tme.dwFlags = TME_LEAVE;
						tme.hwndTrack = m_osGlobals->m_hwnd;
						tme.dwHoverTime = HOVER_DEFAULT;
						TrackMouseEvent(&tme);
					}
				}
				else if (msg.message == WM_MOUSELEAVE)
					m_mouseIsInClientArea = false;

				m_osGlobals->m_translateWindowsMessageFunc(&msg, m_properties.m_eventQueue, m_pixelScaleX, m_pixelScaleY);
			}
		}
		else
		{
			if (m_isFullScreen != m_isFullScreenDesired)
			{
				if (m_isFullScreenDesired)
					BecomeFullScreen();
				else
					BecomeWindowed();
			}

			int clientWidth = 0;
			int clientHeight = 0;
			SDL_GetWindowSize(m_window, &clientWidth, &clientHeight);


			unsigned int desiredWidth = clientWidth;
			unsigned int desiredHeight = clientHeight;
			if (desiredWidth != m_windowWidthPhysical || desiredHeight != m_windowHeightPhysical || m_isResolutionResetDesired)
			{
				uint32_t prevWidthPhysical = m_windowWidthPhysical;
				uint32_t prevHeightPhysical = m_windowHeightPhysical;
				uint32_t prevWidthVirtual = m_windowWidthVirtual;
				uint32_t prevHeightVirtual = m_windowHeightVirtual;
				uint32_t virtualWidth = m_windowWidthVirtual;
				uint32_t virtualHeight = m_windowHeightVirtual;
				float pixelScaleX = 1.0f;
				float pixelScaleY = 1.0f;

				if (m_properties.m_adjustRequestedResolutionFunc(m_properties.m_adjustRequestedResolutionFuncContext, desiredWidth, desiredHeight, virtualWidth, virtualHeight, pixelScaleX, pixelScaleY))
				{
					bool resizedOK = ResizeOpenGLWindow(m_windowWidthPhysical, m_windowHeightPhysical, desiredWidth, desiredHeight, logger);
					resizedOK = resizedOK && InitBackBuffer(virtualWidth, virtualHeight);

					if (!resizedOK)
						break;	// Critical video driver error, exit

					m_windowWidthVirtual = virtualWidth;
					m_windowHeightVirtual = virtualHeight;
					m_pixelScaleX = pixelScaleX;
					m_pixelScaleY = pixelScaleY;
					m_isResolutionResetDesired = false;

					if (GpVOSEvent *resizeEvent = m_properties.m_eventQueue->QueueEvent())
					{
						resizeEvent->m_eventType = GpVOSEventTypes::kVideoResolutionChanged;
						resizeEvent->m_event.m_resolutionChangedEvent.m_prevWidth = prevWidthVirtual;
						resizeEvent->m_event.m_resolutionChangedEvent.m_prevHeight = prevHeightVirtual;
						resizeEvent->m_event.m_resolutionChangedEvent.m_newWidth = m_windowWidthVirtual;
						resizeEvent->m_event.m_resolutionChangedEvent.m_newHeight = m_windowHeightVirtual;
					}
				}
			}

			GpDisplayDriverTickStatus_t tickStatus = PresentFrameAndSync();
			if (tickStatus == GpDisplayDriverTickStatuses::kFatalFault || tickStatus == GpDisplayDriverTickStatuses::kApplicationTerminated)
				break;
		}
	}

	// Exit
}

void GpDisplayDriver_SDL_GL2::Shutdown()
{
	this->~GpDisplayDriver_SDL_GL2();
	free(this);
}

void GpDisplayDriver_SDL_GL2::GetDisplayResolution(unsigned int *width, unsigned int *height)
{
	if (width)
		*width = m_windowWidthVirtual;

	if (height)
		*height = m_windowHeightVirtual;
}

IGpDisplayDriverSurface *GpDisplayDriver_SDL_GL2::CreateSurface(size_t width, size_t height, size_t pitch, GpPixelFormat_t pixelFormat)
{
	return GpDisplayDriverSurface_GL2::Create(this, width, height, pitch, pixelFormat);
}

void GpDisplayDriver_SDL_GL2::DrawSurface(IGpDisplayDriverSurface *surface, int32_t x, int32_t y, size_t width, size_t height, const GpDisplayDriverSurfaceEffects *effects)
{
	if (!effects)
		effects = &gs_defaultEffects;

	GpGLVertexArray *vaPtr = m_quadVertexArray;
	size_t vbStride = sizeof(float) * 2;
	size_t zero = 0;

	GpDisplayDriverSurface_GL2 *glSurface = static_cast<GpDisplayDriverSurface_GL2*>(surface);
	GpPixelFormat_t pixelFormat = glSurface->GetPixelFormat();

	DrawQuadProgram *program = nullptr;

	if (pixelFormat == GpPixelFormats::k8BitStandard || pixelFormat == GpPixelFormats::k8BitCustom)
		program = m_useICCProfile ? &m_drawQuadPaletteICCProgram : &m_drawQuadPaletteProgram;
	else if (pixelFormat == GpPixelFormats::kRGB555)
	{
		return;
	}
	else if (pixelFormat == GpPixelFormats::kRGB32)
	{
		return;
	}
	else
	{
		return;
	}

	m_gl.UseProgram(program->m_program->GetID());

	{
		const float twoDivWidth = 2.0f / static_cast<float>(m_windowWidthVirtual);
		const float negativeTwoDivHeight = -2.0f / static_cast<float>(m_windowHeightVirtual);

		GLfloat ndcOriginAndDimensions[4] =
		{

			static_cast<GLfloat>(x) * twoDivWidth - 1.0f,
			static_cast<GLfloat>(y) * negativeTwoDivHeight + 1.0f,
			static_cast<GLfloat>(width) * twoDivWidth,
			static_cast<GLfloat>(height) * negativeTwoDivHeight,
		};

		GLfloat surfaceDimensions_TextureRegion[4] =
		{
			static_cast<GLfloat>(glSurface->GetImageWidth()),
			static_cast<GLfloat>(glSurface->GetHeight()),
			static_cast<GLfloat>(static_cast<float>(glSurface->GetImageWidth()) / static_cast<float>(glSurface->GetPaddedTextureWidth())),
			1.f
		};

		m_gl.Uniform4fv(program->m_vertexNDCOriginAndDimensionsLocation, 1, reinterpret_cast<const GLfloat*>(ndcOriginAndDimensions));
		m_gl.Uniform4fv(program->m_vertexSurfaceDimensionsLocation, 1, reinterpret_cast<const GLfloat*>(surfaceDimensions_TextureRegion));

		GLfloat modulation[4] = { 1.f, 1.f, 1.f, 1.f };
		GLfloat flickerAxis[2] = { 0.f, 0.f };
		GLfloat flickerStart = -1.f;
		GLfloat flickerEnd = -2.f;

		if (effects->m_flicker)
		{
			flickerAxis[0] = effects->m_flickerAxisX;
			flickerAxis[1] = effects->m_flickerAxisY;
			flickerStart = effects->m_flickerStartThreshold;
			flickerEnd = effects->m_flickerEndThreshold;
		}

		float desaturation = effects->m_desaturation;

		if (effects->m_darken)
			for (int i = 0; i < 3; i++)
				modulation[i] = 0.5f;

		m_gl.Uniform4fv(program->m_pixelModulationLocation, 1, modulation);
		m_gl.Uniform2fv(program->m_pixelFlickerAxisLocation, 1, flickerAxis);
		m_gl.Uniform1fv(program->m_pixelFlickerStartThresholdLocation, 1, &flickerStart);
		m_gl.Uniform1fv(program->m_pixelFlickerEndThresholdLocation, 1, &flickerEnd);
	}

	GLint vpos[1] = { program->m_vertexPosUVLocation };

	m_quadVertexArray->Activate(vpos);

	m_gl.ActiveTexture(GL_TEXTURE0);
	m_gl.BindTexture(GL_TEXTURE_2D, glSurface->GetTexture()->GetID());
	m_gl.Uniform1i(program->m_pixelSurfaceTextureLocation, 0);

	if (pixelFormat == GpPixelFormats::k8BitStandard || pixelFormat == GpPixelFormats::k8BitCustom)
	{
		m_gl.ActiveTexture(GL_TEXTURE1);
		m_gl.BindTexture(GL_TEXTURE_2D, m_paletteTexture->GetID());
		m_gl.Uniform1i(program->m_pixelPaletteTextureLocation, 1);
	}

	m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_quadIndexBuffer->GetID());
	m_gl.DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);
	m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);


	if (pixelFormat == GpPixelFormats::k8BitStandard || pixelFormat == GpPixelFormats::k8BitCustom)
	{
		m_gl.ActiveTexture(GL_TEXTURE1);
		m_gl.BindTexture(GL_TEXTURE_2D, 0);
	}

	m_gl.ActiveTexture(GL_TEXTURE0);
	m_gl.BindTexture(GL_TEXTURE_2D, 0);

	m_quadVertexArray->Deactivate(vpos);

	m_gl.UseProgram(0);
}

IGpCursor *GpDisplayDriver_SDL_GL2::LoadCursor(bool isColor, int cursorID)
{
	return new GpCursor_SDL2();
}

void GpDisplayDriver_SDL_GL2::SetCursor(IGpCursor *cursor)
{
}

void GpDisplayDriver_SDL_GL2::SetStandardCursor(EGpStandardCursor_t standardCursor)
{
}

void GpDisplayDriver_SDL_GL2::UpdatePalette(const void *paletteData)
{
	m_gl.BindTexture(GL_TEXTURE_2D, m_paletteTexture->GetID());
	m_gl.TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 256, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, paletteData);
	m_gl.BindTexture(GL_TEXTURE_2D, 0);
}

void GpDisplayDriver_SDL_GL2::SetBackgroundColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
{
	uint8_t rgba[4] = { r, g, b, a };
	for (int i = 0; i < 4; i++)
		m_bgColor[i] = static_cast<float>(rgba[i]) / 255.0f;
}

void GpDisplayDriver_SDL_GL2::SetBackgroundDarkenEffect(bool isDark)
{
	m_bgIsDark = isDark;
}

void GpDisplayDriver_SDL_GL2::SetUseICCProfile(bool useICCProfile)
{
	m_useICCProfile = useICCProfile;
}

void GpDisplayDriver_SDL_GL2::RequestToggleFullScreen(uint32_t timestamp)
{
	// Alt-Enter gets re-sent after a full-screen toggle, so we ignore toggle requests until half a second has elapsed
	if (timestamp == 0 || timestamp > m_lastFullScreenToggleTimeStamp + 30)
	{
		m_isFullScreenDesired = !m_isFullScreenDesired;
		m_lastFullScreenToggleTimeStamp = timestamp;
	}
}

void GpDisplayDriver_SDL_GL2::RequestResetVirtualResolution()
{
	m_isResolutionResetDesired = true;
}

bool GpDisplayDriver_SDL_GL2::IsFullScreen() const
{
	return m_isFullScreenDesired;
}

const GpDisplayDriverProperties &GpDisplayDriver_SDL_GL2::GetProperties() const
{
	return m_properties;
}

IGpPrefsHandler *GpDisplayDriver_SDL_GL2::GetPrefsHandler() const
{
	return const_cast<GpDisplayDriver_SDL_GL2*>(this);
}

void GpDisplayDriver_SDL_GL2::ApplyPrefs(const void *identifier, size_t identifierSize, const void *contents, size_t contentsSize, uint32_t version)
{
}

bool GpDisplayDriver_SDL_GL2::SavePrefs(void *context, WritePrefsFunc_t writeFunc)
{
	return true;
}

const GpGLFunctions *GpDisplayDriver_SDL_GL2::GetGLFunctions() const
{
	return &m_gl;
}



template<GLuint TShaderType>
GpComPtr<GpGLShader<TShaderType>> GpDisplayDriver_SDL_GL2::CreateShader(const char *shaderSrc)
{
	size_t shaderCodeLength = strlen(shaderSrc);
	GpComPtr<GpGLShader<TShaderType>> shader(GpGLShader<TShaderType>::Create(this));
	if (shader == nullptr)
		return shader;

	const GLchar *shaderSrcGL = reinterpret_cast<const GLchar*>(shaderSrc);
	GLint shaderLenGL = static_cast<GLint>(shaderCodeLength);
	m_gl.ShaderSource(shader->GetID(), 1, &shaderSrcGL, &shaderLenGL);
	m_gl.CompileShader(shader->GetID());

	GLint compiled = 0;
	m_gl.GetShaderiv(shader->GetID(), GL_COMPILE_STATUS, &compiled);
	if (!compiled)
	{
		GLint infoLength = 0;
		m_gl.GetShaderiv(shader->GetID(), GL_INFO_LOG_LENGTH, &infoLength);

		std::vector<char> log;
		log.resize(infoLength + 1);
		log[infoLength] = '\0';

		m_gl.GetShaderInfoLog(shader->GetID(), static_cast<GLsizei>(log.size() - 1), nullptr, reinterpret_cast<GLchar*>(&log[0]));

		const char *errorMsg = &log[0];

		return GpComPtr<GpGLShader<TShaderType>>();
	}

	return shader;
}

void GpDisplayDriver_SDL_GL2::StartOpenGLForWindow(IGpLogDriver *logger)
{
	SDL_GLContext context = SDL_GL_CreateContext(m_window);
	SDL_GL_SetSwapInterval(1);
}

bool GpDisplayDriver_SDL_GL2::InitResources(uint32_t virtualWidth, uint32_t virtualHeight)
{
	IGpLogDriver *logger = m_properties.m_logger;

	if (logger)
		logger->Printf(IGpLogDriver::Category_Information, "GpDisplayDriver_SDL_GL2::InitResources");

	if (!InitBackBuffer(virtualWidth, virtualHeight))
		return false;

	// Quad index buffer
	{
		const uint16_t indexBufferData[] = { 0, 1, 2, 1, 3, 2 };

		m_quadIndexBuffer = GpGLBuffer::Create(this);
		if (!m_quadIndexBuffer)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitResources: CreateBuffer for draw quad index buffer failed");

			return false;
		}

		m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_quadIndexBuffer->GetID());
		m_gl.BufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexBufferData), indexBufferData, GL_STATIC_DRAW);
		m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	}

	// Quad vertex buffer
	{
		const float vertexBufferData[] =
		{
			0.f, 0.f,
			1.f, 0.f,
			0.f, 1.f,
			1.f, 1.f,
		};

		m_quadVertexBufferKeepalive = GpGLBuffer::Create(this);
		if (!m_quadVertexBufferKeepalive)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitResources: GpGLBuffer::Create for draw quad vertex buffer failed");

			return false;
		}

		m_gl.BindBuffer(GL_ARRAY_BUFFER, m_quadVertexBufferKeepalive->GetID());
		m_gl.BufferData(GL_ARRAY_BUFFER, sizeof(vertexBufferData), vertexBufferData, GL_STATIC_DRAW);
		m_gl.BindBuffer(GL_ARRAY_BUFFER, 0);

		m_quadVertexArray = GpGLVertexArray::Create(this);
		if (!m_quadVertexBufferKeepalive)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitResources: GpGLVertexArray::Create for draw quad vertex buffer failed");

			return false;
		}

		GpGLVertexArraySpec specs[] =
		{
			m_quadVertexBufferKeepalive,
			0,					// index
			2,					// size
			GL_FLOAT,			// type
			GL_FALSE,			// normalized
			sizeof(float) * 2,	// stride
			0
		};

		if (!m_quadVertexArray->InitWithSpecs(specs, sizeof(specs) / sizeof(specs[0])))
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitResources: InitWithSpecs for draw quad vertex buffer failed");

			return false;
		}
	}

	GpComPtr<GpGLShader<GL_VERTEX_SHADER>> drawQuadVertexShader = CreateShader<GL_VERTEX_SHADER>(GpBinarizedShaders::g_drawQuadV_GL2);
	GpComPtr<GpGLShader<GL_FRAGMENT_SHADER>> drawQuadPalettePixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuadPaletteP_GL2);
	//m_drawQuadRGBPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuadRGBP_GL2);
	//m_drawQuad15BitPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuad15BitP_GL2);
	GpComPtr<GpGLShader<GL_FRAGMENT_SHADER>> drawQuadPaletteICCPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuadPaletteICCP_GL2);
	//m_drawQuadRGBICCPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuadRGBICCP_GL2);
	//m_drawQuad15BitICCPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_drawQuad15BitICCP_GL2);
	GpComPtr<GpGLShader<GL_FRAGMENT_SHADER>> scaleQuadPixelShader = CreateShader<GL_FRAGMENT_SHADER>(GpBinarizedShaders::g_scaleQuadP_GL2);

	if (!m_drawQuadPaletteProgram.Link(this, drawQuadVertexShader, drawQuadPalettePixelShader)
		//|| !m_drawQuadRGBProgram.Link(this, drawQuadVertexShader, drawQuadRGBPixelShader)
		//|| !m_drawQuad15BitProgram.Link(this, drawQuadVertexShader, drawQuad15BitPixelShader)
		|| !m_drawQuadPaletteICCProgram.Link(this, drawQuadVertexShader, drawQuadPaletteICCPixelShader)
		//|| !m_drawQuadRGBICCProgram.Link(this, drawQuadVertexShader, drawQuadRGBICCPixelShader)
		//|| !m_drawQuad15BitICCProgram.Link(this, drawQuadVertexShader, drawQuad15BitICCPixelShader)
		|| !m_scaleQuadProgram.Link(this, drawQuadVertexShader, scaleQuadPixelShader))
		return false;



	// Palette texture
	{
		uint8_t initialDataBytes[256][4];
		for (int i = 0; i < 256; i++)
		{
			for (int ch = 0; ch < 4; ch++)
				initialDataBytes[i][ch] = 255;
		}

		m_paletteTexture = GpGLTexture::Create(this);
		if (!m_paletteTexture)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitResources: GpGLTexture::Create failed");

			return false;
		}

		m_gl.BindTexture(GL_TEXTURE_2D, m_paletteTexture->GetID());
		m_gl.PixelStorei(GL_UNPACK_ALIGNMENT, 1);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		m_gl.TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 256, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, initialDataBytes);
		m_gl.BindTexture(GL_TEXTURE_2D, 0);
	}

	return true;
}

void GpDisplayDriver_SDL_GL2::BecomeFullScreen()
{
	SDL_GetWindowPosition(m_window, &m_windowModeRevertX, &m_windowModeRevertY);
	SDL_GetWindowSize(m_window, &m_windowModeRevertWidth, &m_windowModeRevertHeight);
	SDL_SetWindowFullscreen(m_window, SDL_WINDOW_FULLSCREEN_DESKTOP);

	m_isFullScreen = true;
}

void GpDisplayDriver_SDL_GL2::BecomeWindowed()
{
	SDL_SetWindowFullscreen(m_window, 0);
	SDL_SetWindowPosition(m_window, m_windowModeRevertX, m_windowModeRevertY);
	SDL_SetWindowSize(m_window, m_windowModeRevertWidth, m_windowModeRevertHeight);

	m_isFullScreen = false;
}

bool GpDisplayDriver_SDL_GL2::ResizeOpenGLWindow(uint32_t &windowWidth, uint32_t &windowHeight, uint32_t desiredWidth, uint32_t desiredHeight, IGpLogDriver *logger)
{
	if (logger)
		logger->Printf(IGpLogDriver::Category_Information, "ResizeOpenGLWindow: %i x %i", static_cast<int>(desiredWidth), static_cast<int>(desiredHeight));

	if (desiredWidth < 640)
		desiredWidth = 640;
	else if (desiredWidth > MAXDWORD)
		desiredWidth = MAXDWORD;

	if (desiredHeight < 480)
		desiredHeight = 480;
	else if (desiredHeight > MAXDWORD)
		desiredHeight = MAXDWORD;

	if (logger)
		logger->Printf(IGpLogDriver::Category_Information, "ResizeOpenGLWindow: Adjusted dimensions: %i x %i", static_cast<int>(desiredWidth), static_cast<int>(desiredHeight));

	SDL_SetWindowSize(m_window, desiredWidth, desiredHeight);

	windowWidth = desiredWidth;
	windowHeight = desiredHeight;

	return true;
}

bool GpDisplayDriver_SDL_GL2::InitBackBuffer(uint32_t width, uint32_t height)
{
	IGpLogDriver *logger = m_properties.m_logger;

	if (logger)
		logger->Printf(IGpLogDriver::Category_Information, "GpDisplayDriver_SDL_GL2::InitBackBuffer");

	{
		m_virtualScreenTexture = GpGLTexture::Create(this);
		if (!m_virtualScreenTexture)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitBackBuffer: GpGLTexture::Create for virtual screen texture failed");

			return false;
		}

		m_gl.BindTexture(GL_TEXTURE_2D, m_virtualScreenTexture->GetID());
		m_gl.PixelStorei(GL_UNPACK_ALIGNMENT, 1);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		m_gl.TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		m_gl.TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
		m_gl.BindTexture(GL_TEXTURE_2D, 0);
	}

	{
		m_virtualScreenTextureRTV = GpGLRenderTargetView::Create(this);

		if (!m_virtualScreenTextureRTV)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitBackBuffer: GpGLRenderTargetView::Create for virtual screen texture failed");

			return false;
		}

		m_gl.BindFramebuffer(GL_FRAMEBUFFER, m_virtualScreenTextureRTV->GetID());
		m_gl.FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_virtualScreenTexture->GetID(), 0);
		GLenum status = m_gl.CheckFramebufferStatus(GL_FRAMEBUFFER);

		if (status != GL_FRAMEBUFFER_COMPLETE)
		{
			if (logger)
				logger->Printf(IGpLogDriver::Category_Error, "GpDisplayDriver_SDL_GL2::InitBackBuffer: Framebuffer complete check failed");

			return false;
		}
	}

	return true;
}


void GpDisplayDriver_SDL_GL2::ScaleVirtualScreen()
{
	m_gl.BindFramebuffer(GL_FRAMEBUFFER, 0);

	m_gl.Viewport(0, 0, m_windowWidthPhysical, m_windowHeightPhysical);

	{
		const float twoDivWidth = 2.0f / static_cast<float>(m_windowWidthPhysical);
		const float twoDivHeight = 2.0f / static_cast<float>(m_windowHeightPhysical);

		// Use the scaled virtual width instead of the physical width to correctly handle cases where the window boundary is in the middle of a pixel
		float fWidth = static_cast<float>(m_windowWidthVirtual) * m_pixelScaleX;
		float fHeight = static_cast<float>(m_windowHeightVirtual) * m_pixelScaleY;

		float ndcOriginsAndDimensions[4] =
		{
			twoDivWidth - 1.0f,
			twoDivHeight - 1.0f,
			fWidth * twoDivWidth,
			fHeight * twoDivHeight
		};

		float surfaceDimensions_TextureRegion[4] =
		{
			static_cast<float>(m_windowWidthVirtual),
			static_cast<float>(m_windowHeightVirtual),
			1.f,
			1.f
		};

		m_gl.UseProgram(m_scaleQuadProgram.m_program->GetID());
		m_gl.Uniform4fv(m_scaleQuadProgram.m_vertexNDCOriginAndDimensionsLocation, 1, reinterpret_cast<const GLfloat*>(ndcOriginsAndDimensions));
		m_gl.Uniform4fv(m_scaleQuadProgram.m_vertexSurfaceDimensionsLocation, 1, reinterpret_cast<const GLfloat*>(surfaceDimensions_TextureRegion));

		float dxdy_dimensions[4] =
		{
			static_cast<float>(static_cast<double>(m_windowWidthVirtual) / static_cast<double>(m_windowWidthPhysical)),
			static_cast<float>(static_cast<double>(m_windowHeightVirtual) / static_cast<double>(m_windowHeightPhysical)),
			m_windowWidthVirtual,
			m_windowHeightVirtual
		};

		m_gl.Uniform4fv(m_scaleQuadProgram.m_pixelDXDYDimensionsLocation, 1, reinterpret_cast<const GLfloat*>(dxdy_dimensions));
	}

	GLint attribLocations[] = { m_scaleQuadProgram.m_vertexPosUVLocation };

	m_quadVertexArray->Activate(attribLocations);

	m_gl.ActiveTexture(GL_TEXTURE0 + 0);
	m_gl.BindTexture(GL_TEXTURE_2D, m_virtualScreenTexture->GetID());
	m_gl.Uniform1i(m_scaleQuadProgram.m_pixelSurfaceTextureLocation, 0);

	m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_quadIndexBuffer->GetID());
	m_gl.DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, nullptr);

	m_gl.UseProgram(0);

	m_gl.ActiveTexture(GL_TEXTURE0 + 0);
	m_gl.BindTexture(GL_TEXTURE_2D, 0);

	m_quadVertexArray->Deactivate(attribLocations);

	m_gl.BindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}


bool GpDisplayDriver_SDL_GL2::DrawQuadProgram::Link(GpDisplayDriver_SDL_GL2 *driver, const GpGLShader<GL_VERTEX_SHADER> *vertexShader, const GpGLShader<GL_FRAGMENT_SHADER> *pixelShader)
{
	m_program = GpGLProgram::Create(driver);
	if (!m_program)
		return false;

	const GpGLFunctions *gl = driver->GetGLFunctions();
	gl->AttachShader(m_program->GetID(), vertexShader->GetID());
	gl->AttachShader(m_program->GetID(), pixelShader->GetID());
	gl->LinkProgram(m_program->GetID());

	GLint linked = 0;
	gl->GetProgramiv(m_program->GetID(), GL_LINK_STATUS, &linked);
	if (!linked)
	{
		GLint logLength = 0;
		gl->GetProgramiv(m_program->GetID(), GL_INFO_LOG_LENGTH, &logLength);

		std::vector<char> errorMsgBuffer;
		errorMsgBuffer.resize(static_cast<size_t>(logLength) + 1);
		errorMsgBuffer[logLength] = '\0';

		gl->GetProgramInfoLog(m_program->GetID(), static_cast<size_t>(logLength), nullptr, reinterpret_cast<GLchar*>(&errorMsgBuffer[0]));
		const char *errorMsg = &errorMsgBuffer[0];

		return false;
	}

	m_vertexNDCOriginAndDimensionsLocation = gl->GetUniformLocation(m_program->GetID(), "ndcOriginAndDimensions");
	m_vertexSurfaceDimensionsLocation = gl->GetUniformLocation(m_program->GetID(), "surfaceDimensions_TextureRegion");
	m_vertexPosUVLocation = gl->GetAttribLocation(m_program->GetID(), "posUV");

	m_pixelModulationLocation = gl->GetUniformLocation(m_program->GetID(), "constants_Modulation");
	m_pixelFlickerAxisLocation = gl->GetUniformLocation(m_program->GetID(), "constants_FlickerAxis");
	m_pixelFlickerStartThresholdLocation = gl->GetUniformLocation(m_program->GetID(), "constants_FlickerStartThreshold");
	m_pixelFlickerEndThresholdLocation = gl->GetUniformLocation(m_program->GetID(), "constants_FlickerEndThreshold");
	m_pixelDesaturationLocation = gl->GetUniformLocation(m_program->GetID(), "constants_Desaturation");

	m_pixelSurfaceTextureLocation = gl->GetUniformLocation(m_program->GetID(), "surfaceTexture");
	m_pixelPaletteTextureLocation = gl->GetUniformLocation(m_program->GetID(), "paletteTexture");

	return true;
}

bool GpDisplayDriver_SDL_GL2::ScaleQuadProgram::Link(GpDisplayDriver_SDL_GL2 *driver, const GpGLShader<GL_VERTEX_SHADER> *vertexShader, const GpGLShader<GL_FRAGMENT_SHADER> *pixelShader)
{
	m_program = GpGLProgram::Create(driver);
	if (!m_program)
		return false;

	const GpGLFunctions *gl = driver->GetGLFunctions();
	gl->AttachShader(m_program->GetID(), vertexShader->GetID());
	gl->AttachShader(m_program->GetID(), pixelShader->GetID());
	gl->LinkProgram(m_program->GetID());

	GLint linked = 0;
	gl->GetProgramiv(m_program->GetID(), GL_LINK_STATUS, &linked);
	if (!linked)
	{
		GLint logLength = 0;
		gl->GetProgramiv(m_program->GetID(), GL_INFO_LOG_LENGTH, &logLength);

		std::vector<char> errorMsgBuffer;
		errorMsgBuffer.resize(static_cast<size_t>(logLength) + 1);
		errorMsgBuffer[logLength] = '\0';
		
		gl->GetProgramInfoLog(m_program->GetID(), static_cast<size_t>(logLength), nullptr, reinterpret_cast<GLchar*>(&errorMsgBuffer[0]));
		const char *errorMsg = &errorMsgBuffer[0];

		return false;
	}

	m_vertexNDCOriginAndDimensionsLocation = gl->GetUniformLocation(m_program->GetID(), "ndcOriginAndDimensions");
	m_vertexSurfaceDimensionsLocation = gl->GetUniformLocation(m_program->GetID(), "surfaceDimensions_TextureRegion");
	m_pixelDXDYDimensionsLocation = gl->GetUniformLocation(m_program->GetID(), "dxdy_dimensions");
	m_vertexPosUVLocation = gl->GetAttribLocation(m_program->GetID(), "posUV");
	m_pixelSurfaceTextureLocation = gl->GetUniformLocation(m_program->GetID(), "surfaceTexture");

	return true;
}

GpDisplayDriverTickStatus_t GpDisplayDriver_SDL_GL2::PresentFrameAndSync()
{
	//SynchronizeCursors();

	float bgColor[4];

	for (int i = 0; i < 4; i++)
		bgColor[i] = m_bgColor[i];

	if (m_bgIsDark)
	{
		for (int i = 0; i < 3; i++)
			bgColor[i] *= 0.25f;
	}

	//ID3D11RenderTargetView *const rtv = m_backBufferRTV;
	GpGLRenderTargetView *const vsRTV = m_virtualScreenTextureRTV;

	m_gl.BindFramebuffer(GL_FRAMEBUFFER, vsRTV->GetID());

	m_gl.Viewport(0, 0, m_windowWidthVirtual, m_windowHeightVirtual);

	m_gl.ClearColor(m_bgColor[0], m_bgColor[1], m_bgColor[2], m_bgColor[3]);
	m_gl.Clear(GL_COLOR_BUFFER_BIT);

	m_properties.m_renderFunc(m_properties.m_renderFuncContext);

	ScaleVirtualScreen();

	GLenum errorCode = m_gl.GetError();

	SDL_GL_SwapWindow(m_window);

	std::chrono::time_point<std::chrono::high_resolution_clock>::duration syncTime = std::chrono::high_resolution_clock::now().time_since_epoch();
	const intmax_t periodNum = std::chrono::high_resolution_clock::period::num;
	const intmax_t periodDen = std::chrono::high_resolution_clock::period::den;

	if (syncTime.count() != 0)
	{
		if (m_syncTimeBase.count() == 0)
			m_syncTimeBase = syncTime;

		std::chrono::time_point<std::chrono::high_resolution_clock>::duration timestamp;
		timestamp = syncTime - m_syncTimeBase;

		bool compacted = false;
		if (m_presentHistory.Size() > 0)
		{
			CompactedPresentHistoryItem &lastItem = m_presentHistory[m_presentHistory.Size() - 1];
			std::chrono::time_point<std::chrono::high_resolution_clock>::duration timeDelta = timestamp - lastItem.m_timestamp;

			if (timeDelta.count() < 0)
				timeDelta = std::chrono::time_point<std::chrono::high_resolution_clock>::duration::zero();	// This should never happen

			if (timeDelta.count() * static_cast<intmax_t>(m_properties.m_frameTimeLockDenominator) * periodNum < periodDen * static_cast<intmax_t>(m_properties.m_frameTimeLockNumerator))
			{
				lastItem.m_numFrames++;
				compacted = true;
			}
		}

		if (!compacted)
		{
			if (m_presentHistory.Size() == m_presentHistory.CAPACITY)
				m_presentHistory.RemoveFromStart();

			CompactedPresentHistoryItem *newItem = m_presentHistory.Append();
			newItem->m_timestamp = timestamp;
			newItem->m_numFrames = 1;
		}
	}

	if (m_presentHistory.Size() >= 2)
	{
		const size_t presentHistorySizeMinusOne = m_presentHistory.Size() - 1;
		unsigned int numFrames = 0;
		for (size_t i = 0; i < presentHistorySizeMinusOne; i++)
			numFrames += m_presentHistory[i].m_numFrames;

		std::chrono::high_resolution_clock::duration timeFrame = m_presentHistory[presentHistorySizeMinusOne].m_timestamp - m_presentHistory[0].m_timestamp;

		unsigned int cancelledFrames = 0;
		std::chrono::high_resolution_clock::duration cancelledTime = std::chrono::high_resolution_clock::duration::zero();

		const int overshootTolerance = 2;

		for (size_t i = 0; i < presentHistorySizeMinusOne; i++)
		{
			std::chrono::high_resolution_clock::duration blockTimeframe = m_presentHistory[i + 1].m_timestamp - m_presentHistory[i].m_timestamp;
			unsigned int blockNumFrames = m_presentHistory[i].m_numFrames;

			if (blockTimeframe.count() * static_cast<intmax_t>(numFrames) >= timeFrame.count() * static_cast<intmax_t>(blockNumFrames) * overshootTolerance)
			{
				cancelledTime += blockTimeframe;
				cancelledFrames += blockNumFrames;
			}
		}

		numFrames -= cancelledFrames;
		timeFrame -= cancelledTime;

		// timeFrame / numFrames = Frame timestep
		// Unless Frame timestep is within the frame lock range, a.k.a.
		// timeFrame / numFrames / qpFreq >= minFrameTimeNum / minFrameTimeDenom

		bool isInFrameTimeLock = false;
		if (timeFrame.count() * static_cast<intmax_t>(m_properties.m_frameTimeLockMinDenominator) * periodNum >= static_cast<intmax_t>(numFrames) * static_cast<intmax_t>(m_properties.m_frameTimeLockMinNumerator) * periodDen
			&& timeFrame.count() * static_cast<intmax_t>(m_properties.m_frameTimeLockMaxDenominator) * periodNum <= static_cast<intmax_t>(numFrames) * static_cast<intmax_t>(m_properties.m_frameTimeLockMaxNumerator) * periodDen)
		{
			isInFrameTimeLock = true;
		}

		std::chrono::high_resolution_clock::duration frameTimeStep = m_frameTimeSliceSize;
		if (!isInFrameTimeLock)
		{
			const int MAX_FRAMES_PER_STEP = 4;

			frameTimeStep = std::chrono::high_resolution_clock::duration(timeFrame.count() / numFrames);
			if (frameTimeStep > m_frameTimeSliceSize * MAX_FRAMES_PER_STEP)
				frameTimeStep = m_frameTimeSliceSize * MAX_FRAMES_PER_STEP;
		}

		m_frameTimeAccumulated += frameTimeStep;
		while (m_frameTimeAccumulated >= m_frameTimeSliceSize)
		{
			GpDisplayDriverTickStatus_t tickStatus = m_properties.m_tickFunc(m_properties.m_tickFuncContext, m_vosFiber);
			m_frameTimeAccumulated -= m_frameTimeSliceSize;

			if (tickStatus != GpDisplayDriverTickStatuses::kOK)
				return tickStatus;
		}
	}

	return GpDisplayDriverTickStatuses::kOK;
}

IGpDisplayDriver *GpDriver_CreateDisplayDriver_SDL_GL2(const GpDisplayDriverProperties &properties)
{
	GpDisplayDriver_SDL_GL2 *driver = static_cast<GpDisplayDriver_SDL_GL2*>(malloc(sizeof(GpDisplayDriver_SDL_GL2)));
	if (!driver)
		return nullptr;

	new (driver) GpDisplayDriver_SDL_GL2(properties);

	if (!driver->Init())
	{
		driver->Shutdown();
		return nullptr;
	}

	return driver;
}


template<class T>
T *GpGLObjectImpl<T>::Create(GpDisplayDriver_SDL_GL2 *driver)
{
	T *obj = static_cast<T*>(malloc(sizeof(T)));
	if (!obj)
		return nullptr;

	new (obj) T();

	obj->InitDriver(driver, driver->GetGLFunctions());

	if (!obj->Init())
	{
		obj->Destroy();
		return nullptr;
	}

	return obj;
}

#pragma pop_macro("LoadCursor")