unsigned char* glxReadPNG (TCHAR* file, png_uint_32* w, png_uint_32* h)
{
	FILE* f;
	unsigned char sig[8];
	png_structp png_ptr;
	png_infop   info_ptr;
	unsigned char* image_data;
	int bit_depth;
	int color_type;
	unsigned int rowbytes;
	png_uint_32 i;
	png_bytepp row_pointers;

	if ((f = fopen(file, "rb")) == NULL)
		return NULL;
	fread(sig, sizeof(*sig), sizeof(sig), f);
	if (!png_check_sig(sig, sizeof(*sig))) {
		fclose(f);
		return NULL;
	}
	if ((png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)) == NULL) {
		fclose(f);
		return NULL;
	}
	if ((info_ptr = png_create_info_struct(png_ptr)) == NULL) {
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		fclose(f);
		return NULL;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(f);
		return NULL;
	}
	png_ptr->io_ptr = (png_voidp) f;
	png_set_sig_bytes(png_ptr, 8);

	png_read_info(png_ptr, info_ptr);
	png_get_IHDR(png_ptr, info_ptr, w, h, &bit_depth, &color_type, NULL, NULL, NULL);
	if (color_type & PNG_COLOR_MASK_ALPHA)
		png_set_strip_alpha(png_ptr);
	if (bit_depth > 8)
		png_set_strip_16(png_ptr);
	if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png_ptr);
	if (color_type == PNG_COLOR_TYPE_PALETTE)
		png_set_palette_to_rgb(png_ptr);
	png_read_update_info(png_ptr, info_ptr);

	rowbytes = png_get_rowbytes(png_ptr, info_ptr);
	if ((image_data = malloc(*h * rowbytes)) == NULL) {
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(f);
		return NULL;
	}
	if ((row_pointers = malloc(*h * sizeof(png_bytep))) == NULL) {
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(f);
		free(image_data);
		return NULL;
	}

	for (i = 0; i < *h; i++)
		row_pointers[*h - 1 - i] = image_data + i*rowbytes;
	png_read_image(png_ptr, row_pointers);
	free(row_pointers);
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	fclose(f);

	return image_data;
}

//global
int w;
int h;
GLfloat xrot = 0.0f;
GLfloat yrot = 0.0f;
GLuint imgname;

//static variables for wndproc
static HDC   hdc;
static HGLRC hrc;
static HFONT font;
static RECT  re = {0, 0, 0, 0};
static unsigned char* image;
static int imgw, imgh;

		case WM_CREATE:
		{
			PIXELFORMATDESCRIPTOR pfd = {
				sizeof(pfd),
				1,
				PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,
				PFD_TYPE_RGBA,
				32,
				0, 0, 0, 0, 0, 0,
				0,
				0,
				0,
				0, 0, 0, 0,
				32,
				0,
				0,
				PFD_MAIN_PLANE,
				0,
				0, 0, 0
			};
			if ((hdc = GetDC(hwnd)) == NULL ||
			    !SetPixelFormat(hdc, ChoosePixelFormat(hdc, &pfd), &pfd) ||
			    (hrc = wglCreateContext(hdc)) == NULL ||
			    !wglMakeCurrent(hdc, hrc))
			{
				Error();
				PostQuitMessage(1);
				break;
			}
			font = CreateFont(-MulDiv(12, GetDeviceCaps(hdc, LOGPIXELSY), 72), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "MS Shell Dlg");
			if (font == NULL) {
				Error();
				PostQuitMessage(1);
				break;
			}
			SetTextColor(hdc, RGB(0, 0xFF, 0));
			SetBkMode(hdc, TRANSPARENT);
			if ((image = glxReadPNG(TEXT("ogl.png"), &imgw, &imgh)) == NULL) {
				Error();
				PostQuitMessage(1);
				break;
			}
			glGenTextures(1, &imgname);
			glBindTexture(GL_TEXTURE_2D, imgname);
			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR);
			free(image);
			glEnable(GL_TEXTURE_2D);
			glShadeModel(GL_SMOOTH);
			glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
			glClearDepth(1.0f);
			glEnable(GL_DEPTH_TEST);
			glDepthFunc(GL_LEQUAL);
			glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
			break;
		}

GLvoid glxError (GLvoid)
{
	GLenum error;
	while ((error = glGetError()) != GL_NO_ERROR)
		MessageBox(NULL, gluErrorString(error), NULL, MB_OK | MB_ICONSTOP);
}