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class Font
{
public:
	Font()
	{
		if (FT_Init_FreeType(&ftLibrary))
		{
			printf("Could not initialize FreeType library\n");
			return;
		}
		glGenBuffers(1,&iVerts);
	}

	bool Load(std::string sFont, unsigned int Size = 18.0f)
	{
		if (FT_New_Face(ftLibrary,sFont.c_str(),0,&ftFace))
		{
			printf("Could not open font: %s\n",sFont.c_str());
			return true;
		}
		iSize = Size;
		FT_Set_Pixel_Sizes(ftFace,0,(int)iSize);

		FT_GlyphSlot gGlyph = ftFace->glyph;

		//Generating the texture atlas.
		//Rather than some amazing rectangular packing method, I'm just going
		//to have one long strip of letters with the height being that of the texture size.
		unsigned int width = 0;
		unsigned int height = 0;

		for (int i = 32; i < 128; i++)
		{
			if (FT_Load_Char(ftFace,i,FT_LOAD_RENDER))
			{
				printf("Error rendering letter %c for font %s.\n",i,sFont.c_str());
			}

			width += gGlyph->bitmap.width;
			height = std::max(height,(unsigned int)gGlyph->bitmap.rows);
		}

		//Generate the openGL texture
		glActiveTexture(GL_TEXTURE0);

		//if I texture exists then delete it.
		iTexture ? glDeleteBuffers(1,&iTexture):0;

		glGenTextures(1,&iTexture);
		glBindTexture(GL_TEXTURE_2D,iTexture);
		glPixelStorei(GL_UNPACK_ALIGNMENT,1);
		glTexImage2D(GL_TEXTURE_2D,0,GL_ALPHA,width,height,0,GL_ALPHA,GL_UNSIGNED_BYTE,0);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		//load the glyphs and set the glyph data
		int x = 0;
		for (int i = 32; i < 128; i++)
		{
			if (FT_Load_Char(ftFace,i,FT_LOAD_RENDER))
			{
				//if it cant load the character
				continue;
			}
			//load the glyph map into the texture
			glTexSubImage2D(GL_TEXTURE_2D,0,x,0,
				gGlyph->bitmap.width,
				gGlyph->bitmap.rows,
				GL_ALPHA,
				GL_UNSIGNED_BYTE,
				gGlyph->bitmap.buffer);

			//move the "pen" down the strip
			x += gGlyph->bitmap.width;


			chars[i].ax = (float)(gGlyph->advance.x >> 6);
			chars[i].ay = (float)(gGlyph->advance.y >> 6);

			chars[i].bw = (float)gGlyph->bitmap.width;
			chars[i].bh = (float)gGlyph->bitmap.rows;

			chars[i].bl = (float)gGlyph->bitmap_left;
			chars[i].bt = (float)gGlyph->bitmap_top;

			chars[i].tx = (float)x/width;
		}


		//glGetTexImage(GL_TEXTURE_2D,0,GL_RGBA,GL_UNSIGNED_INT,0);

		printf("Loaded font: %s\n",sFont.c_str());
		return true;
	}

	void Draw(std::string sString,Vector2f vPos = Vector2f(0,0),Vector2f vScale = Vector2f(1,1))
	{
		struct pPoint
		{
			pPoint()
			{
				x = y = s = t = 0;
			}
			pPoint(float a,float b,float c,float d)
			{
				x = a;
				y = b;
				s = c;
				t = d;
			}

			float x,y;
			float s,t;
		};

		pPoint* cCoordinates = new pPoint[6*sString.length()];

		int n = 0;

		float x,y;
		x = vPos.x();
		y = vPos.y();
		for (const char *p = sString.c_str(); *p; p++)
		{

			float x2 = x + chars[*p].bl * vScale.x();
			float y2 = -y - chars[*p].bt * vScale.y();
			float w = chars[*p].bw * vScale.x();
			float h = chars[*p].bh * vScale.y();

			x =+ chars[*p].ax * vScale.x();
			y =+ chars[*p].ay * vScale.y();

			//skip characters with no pixels
			//still advances though
			if (!w || !h)
			{
				continue;
			}

			//triangle one
			cCoordinates[n++] = pPoint( x2     , -y2      , chars[*p].tx					 , 0);
			cCoordinates[n++] = pPoint( x2 + w , -y2      , chars[*p].tx + chars[*p].bw / w  , 0);
			cCoordinates[n++] = pPoint( x2     , -y2-h    , chars[*p].tx					 , chars[*p].bh / h);

			cCoordinates[n++] = pPoint( x2 + w , -y2      , chars[*p].tx + chars[*p].bw / w  , 0);
			cCoordinates[n++] = pPoint( x2     , -y2-h    , chars[*p].tx					 , chars[*p].bh / h);
			cCoordinates[n++] = pPoint( x2 + w , -y2-h    , chars[*p].tx + chars[*p].bw / w  , chars[*p].bh / h);

		}

		glBindBuffer(GL_ARRAY_BUFFER,iVerts);
		glBindTexture(GL_TEXTURE_2D,iTexture);

		//Vertices
		glEnableClientState(GL_VERTEX_ARRAY);
		glVertexPointer(2,GL_FLOAT,sizeof(pPoint),(void*)0);
		//TexCoord 0
		glClientActiveTexture(GL_TEXTURE0);
		glEnableClientState(GL_TEXTURE_COORD_ARRAY);
		glTexCoordPointer(2,GL_FLOAT,sizeof(pPoint),(void*)8);

		glCullFace(GL_NONE);

		glBufferData(GL_ARRAY_BUFFER,6*sString.length(),cCoordinates,GL_DYNAMIC_DRAW);
		glDrawArrays(GL_TRIANGLES,0,n);

		glCullFace(GL_BACK);

		glBindBuffer(GL_ARRAY_BUFFER,0);
		glBindBuffer(GL_TEXTURE_2D,0);
		glDisableClientState(GL_VERTEX_ARRAY);
		glDisableClientState(GL_TEXTURE_COORD_ARRAY);

	}

	~Font()
	{
		glDeleteBuffers(1,&iVerts);
		glDeleteBuffers(1,&iTexture);
	}

private:
	unsigned int iSize;

	//openGL texture atlas
	unsigned int iTexture;

	//openGL geometry buffer;
	unsigned int iVerts;

	FT_Library ftLibrary;
	FT_Face ftFace;

	struct Character
	{
		float ax,ay;//Advance
		float bw,bh;//bitmap size
		float bl,bt;//bitmap left and top
		float tx;
	} chars[128];

};