/*****************************************************************************\
     Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
                This file is licensed under the Snes9x License.
   For further information, consult the LICENSE file in the root directory.
\*****************************************************************************/

#include "COpenGL.h"
#include "win32_display.h"
#include "../snes9x.h"
#include "../gfx.h"
#include "../display.h"
#include "wsnes9x.h"
#include <msxml2.h>

#include "../filter/hq2x.h"
#include "../filter/2xsai.h"


COpenGL::COpenGL(void)
{
	hDC = NULL;
	hRC = NULL;
	hWnd = NULL;
	drawTexture = 0;
	initDone = false;
	afterRenderWidth = 0;
	afterRenderHeight = 0;
    outTextureWidth = 0;
    outTextureHeight = 0;
	fullscreen = false;
	shaderFunctionsLoaded = false;
	shader_type = OGL_SHADER_NONE;
	pboFunctionsLoaded = false;
	shaderProgram = 0;
    vertexShader = 0;
    fragmentShader = 0;
	cgContext = NULL;
	cgVertexProgram = cgFragmentProgram = NULL;
	cgAvailable = false;
	frameCount = 0;
	cgShader = NULL;
    glslShader = NULL;
	*currentShaderFile = _T('\0');
}

COpenGL::~COpenGL(void)
{
	DeInitialize();
}

bool COpenGL::Initialize(HWND hWnd)
{
	int pfdIndex;
	RECT windowRect;

	this->hWnd = hWnd;
	this->hDC = GetDC(hWnd);

	PIXELFORMATDESCRIPTOR pfd=
	{
		sizeof(PIXELFORMATDESCRIPTOR),					// Size Of This Pixel Format Descriptor
		1,												// Version Number
		PFD_DRAW_TO_WINDOW |							// Format Must Support Window
		PFD_SUPPORT_OPENGL |							// Format Must Support OpenGL
		PFD_DOUBLEBUFFER,								// Must Support Double Buffering
		PFD_TYPE_RGBA,									// Request An RGBA Format
		32,												// Select Our Color Depth
		0, 0, 0, 0, 0, 0,								// Color Bits Ignored
		0,												// No Alpha Buffer
		0,												// Shift Bit Ignored
		0,												// No Accumulation Buffer
		0, 0, 0, 0,										// Accumulation Bits Ignored
		16,												// 16Bit Z-Buffer (Depth Buffer)
		0,												// No Stencil Buffer
		0,												// No Auxiliary Buffer
		PFD_MAIN_PLANE,									// Main Drawing Layer
		0,												// Reserved
		0, 0, 0											// Layer Masks Ignored
	};
	PIXELFORMATDESCRIPTOR pfdSel;

	if(!(pfdIndex=ChoosePixelFormat(hDC,&pfd))) {
		DeInitialize();
		return false;
	}
	if(!SetPixelFormat(hDC,pfdIndex,&pfd)) {
		// SetPixelFormat can only be called once per window. Vulkan WSI will do
		// this automatically and fall back if it's already been set. Since Vulkan
		// has similar requirements, we don't need to set it any more anyway.
		// DeInitialize();
		// return false;
	}
	if(!(hRC=wglCreateContext(hDC))) {
		DeInitialize();
		return false;
	}
	if(!wglMakeCurrent(hDC,hRC)) {
		DeInitialize();
		return false;
	}

    ogl_LoadFunctions();

	LoadPBOFunctions();

	wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress( "wglSwapIntervalEXT" );

	glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
	glEnable(GL_BLEND);
	glEnable(GL_TEXTURE_2D);

	glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    glOrtho (0.0, 1.0, 0.0, 1.0, -1, 1);

	glVertexPointer(2, GL_FLOAT, 0, vertices);
	glTexCoordPointer(2, GL_FLOAT, 0, texcoords);

	cgAvailable = loadCgFunctions();
	if(cgAvailable) {
		cgContext = cgCreateContext();
		cgShader = new CGLCG(cgContext);
	}

    if (ShaderAvailable() && NPOTAvailable()) {
        glslShader = new GLSLShader();
    }

	ApplyDisplayChanges();

	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
	glClear(GL_COLOR_BUFFER_BIT);
	SwapBuffers(hDC);

	initDone = true;
	return true;
}

void COpenGL::DeInitialize()
{
	initDone = false;
	SetShaders(NULL);
	DestroyDrawSurface();
	wglMakeCurrent(NULL,NULL);
	if(hRC) {
		wglDeleteContext(hRC);
		hRC = NULL;
	}
	if (hDC)
	{
		ReleaseDC(hWnd, hDC);
		hDC = NULL;
	}
	hWnd = NULL;
	afterRenderWidth = 0;
	afterRenderHeight = 0;
    outTextureWidth = 0;
    outTextureHeight = 0;
	shaderFunctionsLoaded = false;
	shader_type = OGL_SHADER_NONE;
    if (glslShader) {
        delete glslShader;
        glslShader = NULL;
    }
	if(cgShader) {
		delete cgShader;
		cgShader = NULL;
	}
	if(cgAvailable)
		unloadCgLibrary();
	cgAvailable = false;
}

void COpenGL::CreateDrawSurface(unsigned int width, unsigned int height)
{
	HRESULT hr;

	if (!NPOTAvailable()) {
		unsigned int neededSize = max(width, height);
		//we need at least 512 pixels (SNES_WIDTH * 2) so we can start with that value
		unsigned int quadTextureSize = 512;
		while (quadTextureSize < neededSize)
			quadTextureSize *= 2;
		width = height = quadTextureSize;
	}

	if(!drawTexture) {
		outTextureWidth = width;
		outTextureHeight = height;
		glGenTextures(1,&drawTexture);
		glBindTexture(GL_TEXTURE_2D,drawTexture);
		glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA, outTextureWidth, outTextureHeight,0,GL_RGB,GL_UNSIGNED_SHORT_5_6_5,NULL);
		if(pboFunctionsLoaded) {
			glGenBuffers(1,&drawBuffer);
			glBindBuffer(GL_PIXEL_UNPACK_BUFFER,drawBuffer);
			glBufferData(GL_PIXEL_UNPACK_BUFFER, outTextureWidth*outTextureHeight *2,NULL,GL_STREAM_DRAW);
			glBindBuffer(GL_PIXEL_UNPACK_BUFFER,0);
		} else {
			noPboBuffer = new BYTE[outTextureWidth*outTextureHeight *2];
		}

		glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
		glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
	}
}

void COpenGL::DestroyDrawSurface()
{
	if(drawTexture) {
		glDeleteTextures(1,&drawTexture);
		drawTexture = NULL;
	}
	if(drawBuffer) {
		glDeleteBuffers(1,&drawBuffer);
		drawBuffer = NULL;
	}
	if(noPboBuffer) {
		delete [] noPboBuffer;
		noPboBuffer = NULL;
	}
}

bool COpenGL::ChangeDrawSurfaceSize(unsigned int width, unsigned int height)
{
	DestroyDrawSurface();
	CreateDrawSurface(width, height);
	SetupVertices();
	return true;
}

void COpenGL::SetupVertices()
{
	vertices[0] = 0.0f;
    vertices[1] = 0.0f;
	vertices[2] = 1.0f;
    vertices[3] = 0.0f;
	vertices[4] = 1.0f;
	vertices[5] = 1.0f;
    vertices[6] = 0.0f;
	vertices[7] = 1.0f;

	float tX = (float)afterRenderWidth / (float)outTextureWidth;
	float tY = (float)afterRenderHeight / (float)outTextureHeight;

	texcoords[0] = 0.0f;
    texcoords[1] = tY;
    texcoords[2] = tX;
    texcoords[3] = tY;
    texcoords[4] = tX;
    texcoords[5] = 0.0f;
    texcoords[6] = 0.0f;
    texcoords[7] = 0.0f;
	glTexCoordPointer(2, GL_FLOAT, 0, texcoords);
}

void wOGLViewportCallback(int source_width, int source_height,
	int viewport_x, int viewport_y,
	int viewport_width, int viewport_height,
	int *out_dst_x, int *out_dst_y,
	int *out_dst_width, int *out_dst_height)
{
	/* get window size here instead of using viewport passed in - we limited the viewport before the glsl render
	   call already, this is simply to position smaller outputs correctly in the actual viewport
	 */
	RECT windowSize;
	GetClientRect(GUI.hWnd, &windowSize);
	RECT displayRect = CalculateDisplayRect(source_width, source_height, windowSize.right, windowSize.bottom);
	*out_dst_x = displayRect.left;
	*out_dst_y = displayRect.top;
	*out_dst_width = displayRect.right - displayRect.left;
	*out_dst_height = displayRect.bottom - displayRect.top;
}

void COpenGL::Render(SSurface Src)
{
	SSurface Dst;
	RECT dstRect;
	unsigned int newFilterScale;
	GLenum error;

	if(!initDone) return;

	//create a new draw surface if the filter scale changes
	dstRect = GetFilterOutputSize(Src);
	if(outTextureWidth != dstRect.right || outTextureHeight != dstRect.bottom)
		ChangeDrawSurfaceSize(dstRect.right, dstRect.bottom);

	if(pboFunctionsLoaded) {
		glBindBuffer(GL_PIXEL_UNPACK_BUFFER, drawBuffer);
		Dst.Surface = (unsigned char *)glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
	} else {
		Dst.Surface = noPboBuffer;
	}
	Dst.Height = outTextureHeight;
	Dst.Width = outTextureWidth;
	Dst.Pitch = outTextureWidth * 2;

	RenderMethod (Src, Dst, &dstRect);
	if(!Settings.AutoDisplayMessages) {
		WinSetCustomDisplaySurface((void *)Dst.Surface, Dst.Pitch/2, dstRect.right-dstRect.left, dstRect.bottom-dstRect.top, GetFilterScale(CurrentScale));
		S9xDisplayMessages ((uint16*)Dst.Surface, Dst.Pitch/2, dstRect.right-dstRect.left, dstRect.bottom-dstRect.top, GetFilterScale(CurrentScale));
	}

	if(pboFunctionsLoaded)
		glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);

	if(afterRenderHeight != dstRect.bottom || afterRenderWidth != dstRect.right) {
		afterRenderHeight = dstRect.bottom;
		afterRenderWidth = dstRect.right;

		ChangeRenderSize(0,0);
	}

	glBindTexture(GL_TEXTURE_2D,drawTexture);
	glPixelStorei(GL_UNPACK_ROW_LENGTH, outTextureWidth);
	glTexSubImage2D (GL_TEXTURE_2D,0,0,0,dstRect.right-dstRect.left,dstRect.bottom-dstRect.top,GL_RGB,GL_UNSIGNED_SHORT_5_6_5,pboFunctionsLoaded?0:noPboBuffer);

	if(pboFunctionsLoaded)
		glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);

	RECT windowSize, displayRect;
	GetClientRect(hWnd, &windowSize);
	//Get maximum rect respecting AR setting
	displayRect = CalculateDisplayRect(afterRenderWidth, afterRenderHeight, windowSize.right, windowSize.bottom);

	// GLSL class does all the rendering, no output needed
	if (shader_type == OGL_SHADER_GLSL) {
		glslShader->render(drawTexture, afterRenderWidth, afterRenderHeight, displayRect.left, displayRect.top, displayRect.right - displayRect.left, displayRect.bottom - displayRect.top, wOGLViewportCallback);
	}
	else { // for CG shaders and old style .shader files the last pass is done here, same as no shader
		if(shader_type == OGL_SHADER_CG) {
			xySize inputSize = { (float)afterRenderWidth, (float)afterRenderHeight };
			xySize xywindowSize = { (double)windowSize.right, (double)windowSize.bottom };
			xySize viewportSize = { (double)(displayRect.right - displayRect.left),
				                    (double)(displayRect.bottom - displayRect.top) };
			xySize textureSize = { (double)outTextureWidth, (double)outTextureHeight };
			cgShader->Render(drawTexture, textureSize, inputSize, viewportSize, xywindowSize);
		}
		else if (shader_type == OGL_SHADER_GLSL_OLD) {
			GLint location;

			float inputSize[2] = { (float)afterRenderWidth, (float)afterRenderHeight };
			float outputSize[2] = { (float)(GUI.Stretch ? windowSize.right : afterRenderWidth),
				(float)(GUI.Stretch ? windowSize.bottom : afterRenderHeight) };
			float textureSize[2] = { (float)outTextureWidth, (float)outTextureHeight };
			float frameCnt = (float)++frameCount;
			location = glGetUniformLocation(shaderProgram, "rubyInputSize");
			glUniform2fv(location, 1, inputSize);

			location = glGetUniformLocation(shaderProgram, "rubyOutputSize");
			glUniform2fv(location, 1, outputSize);

			location = glGetUniformLocation(shaderProgram, "rubyTextureSize");
			glUniform2fv(location, 1, textureSize);
		}
		if (Settings.BilinearFilter) {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		}
		else {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		}

		glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
		glClear(GL_COLOR_BUFFER_BIT);
		glDrawArrays(GL_QUADS, 0, 4);
    }

	glFlush();

	WinThrottleFramerate();

	SwapBuffers(hDC);
	if (GUI.ReduceInputLag)
		glFinish();
}

bool COpenGL::ChangeRenderSize(unsigned int newWidth, unsigned int newHeight)
{
	RECT displayRect, windowSize;
	if(newWidth==0||newHeight==0) {
		GetClientRect(hWnd,&windowSize);
		newWidth = windowSize.right;
		newHeight = windowSize.bottom;
	}
	displayRect=CalculateDisplayRect(afterRenderWidth,afterRenderHeight,newWidth,newHeight);
	glViewport(displayRect.left,newHeight-displayRect.bottom,displayRect.right-displayRect.left,displayRect.bottom-displayRect.top);
	SetupVertices();
	return true;
}

void COpenGL::SetSwapInterval(int frames)
{
    if (wglSwapIntervalEXT)
        wglSwapIntervalEXT(frames);
}

std::vector<GLSLParam>* COpenGL::GetShaderParameters(void)
{
	if (shader_type == OGL_SHADER_GLSL && initDone)
		return &glslShader->param;

	return nullptr;
}

std::function<void(const char *)> COpenGL::GetShaderParametersSaveFunction()
{
	return [&](const char *filename) {
		this->glslShader->save(filename);
	};
}

bool COpenGL::ApplyDisplayChanges(void)
{
	if(wglSwapIntervalEXT) {
		wglSwapIntervalEXT(GUI.Vsync?1:0);
	}
	if(GUI.shaderEnabled && GUI.OGLshaderFileName)
		SetShaders(GUI.OGLshaderFileName);
	else
		SetShaders(NULL);

	ChangeRenderSize(0,0);
	return true;
}

bool COpenGL::SetFullscreen(bool fullscreen)
{
	if(!initDone)
		return false;

	if(this->fullscreen==fullscreen)
		return true;

	this->fullscreen = fullscreen;

	if(fullscreen) {
		DEVMODE dmScreenSettings={0};
		dmScreenSettings.dmSize=sizeof(dmScreenSettings);
		dmScreenSettings.dmPelsWidth	= GUI.FullscreenMode.width;
		dmScreenSettings.dmPelsHeight	= GUI.FullscreenMode.height;
		dmScreenSettings.dmBitsPerPel	= GUI.FullscreenMode.depth;
		dmScreenSettings.dmDisplayFrequency = GUI.FullscreenMode.rate;
		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT|DM_DISPLAYFREQUENCY;
		if(ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL) {
			this->fullscreen = false;
			return false;
		}
		ChangeRenderSize(GUI.FullscreenMode.width,GUI.FullscreenMode.height);
	} else {
		ChangeDisplaySettings(NULL,0);
	}



	return true;
}

void COpenGL::SetSnes9xColorFormat()
{
	GUI.ScreenDepth = 16;
	GUI.BlueShift = 0;
	GUI.GreenShift = 6;
	GUI.RedShift = 11;
	S9xBlit2xSaIFilterInit();
	S9xBlitHQ2xFilterInit();
	GUI.NeedDepthConvert = FALSE;
	GUI.DepthConverted = TRUE;
	return;
}

void COpenGL::EnumModes(std::vector<dMode> *modeVector)
{
	DISPLAY_DEVICE dd;
	dd.cb = sizeof(dd);
	DWORD dev = 0;
	int iMode = 0;
	dMode mode;

	while (EnumDisplayDevices(0, dev, &dd, 0))
	{
		if (!(dd.StateFlags & DISPLAY_DEVICE_MIRRORING_DRIVER) && (dd.StateFlags & DISPLAY_DEVICE_PRIMARY_DEVICE))
		{
			DEVMODE dm;
			memset(&dm, 0, sizeof(dm));
			dm.dmSize = sizeof(dm);
			iMode = 0;
			while(EnumDisplaySettings(dd.DeviceName,iMode,&dm)) {
				if(dm.dmBitsPerPel>=16) {
					mode.width = dm.dmPelsWidth;
					mode.height = dm.dmPelsHeight;
					mode.rate = dm.dmDisplayFrequency;
					mode.depth = dm.dmBitsPerPel;
					modeVector->push_back(mode);
				}
				iMode++;
			}
		}
		dev++;
	}
}

bool COpenGL::LoadPBOFunctions()
{
	if(GUI.OGLdisablePBOs)
		return false;

	if(pboFunctionsLoaded)
		return true;

	const char *extensions = (const char *) glGetString(GL_EXTENSIONS);

	if(extensions && strstr(extensions, "pixel_buffer_object")) {

		if(glGenBuffers && glBindBuffer && glBufferData && glDeleteBuffers && glMapBuffer) {
			pboFunctionsLoaded = true;
		}

	}
	return pboFunctionsLoaded;
}

bool COpenGL::LoadShaderFunctions()
{
	if(shaderFunctionsLoaded)
		return true;

	const char *extensions = (const char *) glGetString(GL_EXTENSIONS);

    if(extensions && strstr(extensions, "fragment_program")) {

		if(glCreateProgram      &&
		   glCreateShader       &&
		   glCompileShader      &&
		   glDeleteShader       &&
		   glDeleteProgram      &&
		   glAttachShader       &&
		   glDetachShader       &&
		   glLinkProgram        &&
		   glUseProgram         &&
		   glShaderSource       &&
		   glGetUniformLocation &&
		   glUniform2fv) {
			   shaderFunctionsLoaded = true;
		}
	}
	return shaderFunctionsLoaded;
}

bool COpenGL::SetShaders(const TCHAR *file)
{
	if (file && lstrcmp(file, currentShaderFile) == 0)
		return true;

	SetShadersCG(NULL);
	SetShadersGLSL(NULL);
	SetShadersGLSL_OLD(NULL);
	shader_type = OGL_SHADER_NONE;

	if (file) {
		lstrcpy(currentShaderFile, file);
		if ((lstrlen(file) > 3 && _tcsncicmp(&file[lstrlen(file) - 3], TEXT(".cg"), 3) == 0) ||
			(lstrlen(file) > 4 && _tcsncicmp(&file[lstrlen(file) - 4], TEXT(".cgp"), 4) == 0)) {
			return SetShadersCG(file);
		}
		else if ((lstrlen(file) > 7 && _tcsncicmp(&file[lstrlen(file) - 7], TEXT(".shader"), 7) == 0)) {
			return SetShadersGLSL_OLD(file);
		}
		else {
			return SetShadersGLSL(file);
		}
	}

	*currentShaderFile = _T('\0');

	return true;
}

void COpenGL::checkForCgError(const char *situation)
{
	char buffer[4096];
	CGerror error = cgGetError();
	const char *string = cgGetErrorString(error);

	if (error != CG_NO_ERROR) {
		sprintf(buffer,
			  "Situation: %s\n"
			  "Error: %s\n\n"
			  "Cg compiler output...\n", situation, string);
		MessageBoxA(0, buffer,
				  "Cg error", MB_OK|MB_ICONEXCLAMATION);
		if (error == CG_COMPILER_ERROR) {
			MessageBoxA(0, cgGetLastListing(cgContext),
					  "Cg compilation error", MB_OK|MB_ICONEXCLAMATION);
		}
	}
}

bool COpenGL::SetShadersCG(const TCHAR *file)
{
	if(!cgAvailable) {
		if(file)
			MessageBox(NULL, TEXT("The CG runtime is unavailable, CG shaders will not run.\nConsult the snes9x readme for information on how to obtain the runtime."), TEXT("CG Error"),
				MB_OK|MB_ICONEXCLAMATION);
        return false;
    }

	if(!cgShader->LoadShader(file))
		return false;

	shader_type = OGL_SHADER_CG;

	return true;
}

bool COpenGL::SetShadersGLSL(const TCHAR *glslFileName)
{
	if (!glslShader)
		return false;

	glslShader->destroy();

    if (!glslFileName)
        return false;

    if(!glslShader->load_shader(_tToChar(glslFileName))) {
        return false;
    }

	shader_type = OGL_SHADER_GLSL;

    return true;
}

bool COpenGL::SetShadersGLSL_OLD(const TCHAR *glslFileName)
{
	char *fragment = NULL, *vertex = NULL;
	IXMLDOMDocument * pXMLDoc = NULL;
	IXMLDOMElement * pXDE = NULL;
	IXMLDOMNode * pXDN = NULL;
	HRESULT hr;
	BSTR queryString, nodeContent;

	TCHAR errorMsg[MAX_PATH + 50];

	if (fragmentShader) {
		glDetachShader(shaderProgram, fragmentShader);
		glDeleteShader(fragmentShader);
		fragmentShader = 0;
	}
	if (vertexShader) {
		glDetachShader(shaderProgram, vertexShader);
		glDeleteShader(vertexShader);
		vertexShader = 0;
	}
	if (shaderProgram) {
		glUseProgram(0);
		glDeleteProgram(shaderProgram);
		shaderProgram = 0;
	}

	if (glslFileName == NULL || *glslFileName == TEXT('\0'))
		return true;

	if (!LoadShaderFunctions()) {
		MessageBox(NULL, TEXT("Unable to load OpenGL shader functions"), TEXT("Shader Loading Error"),
			MB_OK | MB_ICONEXCLAMATION);
		return false;
	}

	hr = CoCreateInstance(CLSID_DOMDocument, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pXMLDoc));

	if (FAILED(hr)) {
		MessageBox(NULL, TEXT("Error creating XML Parser"), TEXT("Shader Loading Error"),
			MB_OK | MB_ICONEXCLAMATION);
		return false;
	}

	VARIANT fileName;
	VARIANT_BOOL ret;
	fileName.vt = VT_BSTR;
#ifdef UNICODE
	fileName.bstrVal = SysAllocString(glslFileName);
#else
	wchar_t tempfilename[MAX_PATH];
	MultiByteToWideChar(CP_UTF8, 0, glslFileName, -1, tempfilename, MAX_PATH);
	fileName.bstrVal = SysAllocString(tempfilename);
#endif
	hr = pXMLDoc->load(fileName, &ret);
	SysFreeString(fileName.bstrVal);

	if (FAILED(hr) || hr == S_FALSE) {
		_stprintf(errorMsg, TEXT("Error loading GLSL shader file:\n%s"), glslFileName);
		MessageBox(NULL, errorMsg, TEXT("Shader Loading Error"), MB_OK | MB_ICONEXCLAMATION);
		pXMLDoc->Release();
		return false;
	}

	VARIANT attributeValue;
	BSTR attributeName;

	hr = pXMLDoc->get_documentElement(&pXDE);
	if (FAILED(hr) || hr == S_FALSE) {
		_stprintf(errorMsg, TEXT("Error loading root element from file:\n%s"), glslFileName);
		MessageBox(NULL, errorMsg, TEXT("Shader Loading Error"), MB_OK | MB_ICONEXCLAMATION);
		pXMLDoc->Release();
		return false;
	}

	attributeName = SysAllocString(L"language");
	pXDE->getAttribute(attributeName, &attributeValue);
	SysFreeString(attributeName);
	pXDE->Release();

	if (attributeValue.vt != VT_BSTR || lstrcmpiW(attributeValue.bstrVal, L"glsl")) {
		_stprintf(errorMsg, TEXT("Shader language is <%s>, expected <GLSL> in file:\n%s"), attributeValue.bstrVal, glslFileName);
		MessageBox(NULL, errorMsg, TEXT("Shader Loading Error"), MB_OK | MB_ICONEXCLAMATION);
		if (attributeValue.vt == VT_BSTR) SysFreeString(attributeValue.bstrVal);
		pXMLDoc->Release();
		return false;
	}
	if (attributeValue.vt == VT_BSTR) SysFreeString(attributeValue.bstrVal);

	queryString = SysAllocString(L"/shader/fragment");
	hr = pXMLDoc->selectSingleNode(queryString, &pXDN);
	SysFreeString(queryString);

	if (hr == S_OK) {
		hr = pXDN->get_text(&nodeContent);
		if (hr == S_OK) {
			int requiredChars = WideCharToMultiByte(CP_ACP, 0, nodeContent, -1, fragment, 0, NULL, NULL);
			fragment = new char[requiredChars];
			WideCharToMultiByte(CP_UTF8, 0, nodeContent, -1, fragment, requiredChars, NULL, NULL);
		}
		SysFreeString(nodeContent);
		pXDN->Release();
		pXDN = NULL;
	}

	queryString = SysAllocString(L"/shader/vertex");
	hr = pXMLDoc->selectSingleNode(queryString, &pXDN);
	SysFreeString(queryString);

	if (hr == S_OK) {
		hr = pXDN->get_text(&nodeContent);
		if (hr == S_OK) {
			int requiredChars = WideCharToMultiByte(CP_ACP, 0, nodeContent, -1, vertex, 0, NULL, NULL);
			vertex = new char[requiredChars];
			WideCharToMultiByte(CP_UTF8, 0, nodeContent, -1, vertex, requiredChars, NULL, NULL);
		}
		SysFreeString(nodeContent);
		pXDN->Release();
		pXDN = NULL;
	}

	pXMLDoc->Release();

	if (!fragment && !vertex) {
		_stprintf(errorMsg, TEXT("No vertex or fragment program in file:\n%s"), glslFileName);
		MessageBox(NULL, errorMsg, TEXT("Shader Loading Error"), MB_OK | MB_ICONEXCLAMATION);
		return false;
	}

	shaderProgram = glCreateProgram();
	if (vertex) {
		vertexShader = glCreateShader(GL_VERTEX_SHADER);
		glShaderSource(vertexShader, 1, (const GLchar **)&vertex, NULL);
		glCompileShader(vertexShader);
		glAttachShader(shaderProgram, vertexShader);
		delete[] vertex;
	}
	if (fragment) {
		fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
		glShaderSource(fragmentShader, 1, (const GLchar **)&fragment, NULL);
		glCompileShader(fragmentShader);
		glAttachShader(shaderProgram, fragmentShader);
		delete[] fragment;
	}

	glLinkProgram(shaderProgram);
	glUseProgram(shaderProgram);

	shader_type = OGL_SHADER_GLSL_OLD;

	return true;
}

bool COpenGL::ShaderAvailable()
{
    const char *extensions = (const char *)glGetString(GL_EXTENSIONS);

    if (!extensions)
        return false;

    if (strstr(extensions, "fragment_program") ||
        strstr(extensions, "fragment_shader"))
    {
        return true;
    }

    return false;
}

bool COpenGL::NPOTAvailable()
{
    const char *extensions = (const char *)glGetString(GL_EXTENSIONS);
    const char *version = (const char *)glGetString(GL_VERSION);

    if (!extensions)
        return false;

    int glVersionMajor = 0;
    glVersionMajor = atoi (version);

    if (glVersionMajor >= 2)
        return true;

    if (strstr(extensions, "non_power_of_two") ||
        strstr(extensions, "npot"))
    {
        return true;
    }

    return false;
}