#include "font_opengl.h"

static unsigned int _pow2(unsigned int i)
{
	register unsigned int p2;
	for (p2=1; p2<i; p2<<=1) ;
	return p2;
}

FontOpenGL::FontOpenGL(TrueTypeFont *ttf)
{
	is_valid=true;

	pt=ttf->pt;

	// prepare the OpenGL textures / display lists
	wids=(float *)malloc(sizeof(float)*255);
	bears=(float *)malloc(sizeof(float)*255);
	hoss=(float *)malloc(sizeof(float)*255);
	qvws=(int *)malloc(sizeof(int)*255);
	qvhs=(int *)malloc(sizeof(int)*255);
	qtws=(float *)malloc(sizeof(float)*255);
	qths=(float *)malloc(sizeof(float)*255);
	textures=(unsigned int *)malloc(sizeof(unsigned int)*255);
	glGenTextures(255,textures);

	for (register unsigned char ch=0; ch<255; ch++)
	{
		register int i,j;
		FT_Face face=ttf->face;
		FT_BitmapGlyph bitmap_glyph;
		FT_Glyph glyph;
		FT_Bitmap bitmap;
		unsigned int width,height;
		GLubyte* expanded_data;

		FT_Load_Glyph(face,FT_Get_Char_Index(face,ch),FT_LOAD_DEFAULT);
		FT_Get_Glyph(face->glyph,&glyph);

		FT_Glyph_To_Bitmap(&glyph,ft_render_mode_normal,0,1);
		bitmap_glyph=(FT_BitmapGlyph)glyph;
		bitmap=bitmap_glyph->bitmap;

		width=_pow2(bitmap.width);
		height=_pow2(bitmap.rows);

		expanded_data=(GLubyte *)malloc(sizeof(GLubyte)*width*height);

		for (j=0; j<(int)height;j++)
		{
			for (i=0; i<(int)width; i++)
			{
				expanded_data[i+j*width]=
					(i>=bitmap.width||j>=bitmap.rows)?
					0:bitmap.buffer[i+bitmap.width*j];
			}
		}

		glBindTexture(GL_TEXTURE_2D,textures[ch]);

		glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE);

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

		glTexImage2D(GL_TEXTURE_2D,0,GL_ALPHA,width,height,
			0,GL_ALPHA,GL_UNSIGNED_BYTE,expanded_data);

		free((void *)expanded_data);

		this->wids[ch]=(float)(face->glyph->advance.x>>6);
		this->hoss[ch]=(float)((face->glyph->metrics.horiBearingY-face->glyph->metrics.height)>>6);
		this->bears[ch]=(float)(face->glyph->metrics.horiBearingX>>6);

		this->qvws[ch]=bitmap.width;
		this->qvhs[ch]=bitmap.rows;

		this->qtws[ch]=(float)bitmap.width/(float)width;
		this->qths[ch]=(float)bitmap.rows/(float)height;
	}

	color=Vector4(1.0f);
}

FontOpenGL::~FontOpenGL()
{
	glDeleteTextures(255,textures);
	free((void *)textures);
	free((void *)wids);
	free((void *)bears);
	free((void *)hoss);
	free((void *)qvws);
	free((void *)qvhs);
	free((void *)qtws);
	free((void *)qths);
}

void FontOpenGL::Render(int x,int y,const char *text)
{
	char *ch;

	glPushAttrib(GL_LIST_BIT|GL_CURRENT_BIT|GL_ENABLE_BIT|GL_TRANSFORM_BIT);
		glMatrixMode(GL_MODELVIEW);
		glDisable(GL_LIGHTING);
		glEnable(GL_TEXTURE_2D);
		glDisable(GL_DEPTH_TEST);
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
		glColor4fv((float *)color);

		glPushMatrix();
			glScalef(1.0f,-1.0f,1.0f);
			for (ch=(char *)text; *ch; ch++)
			{
				glPushMatrix();
					glTranslatef(x+bears[*ch],-y-(pt-hoss[*ch]),0);
					glBindTexture(GL_TEXTURE_2D,textures[*ch]);

					glBegin(GL_QUADS);
						glTexCoord2f(0.0f,0.0f);
						glVertex2f(0.0f,(GLfloat)qvhs[*ch]);

						glTexCoord2f(0,(GLfloat)qths[*ch]);
						glVertex2f(0.0f,0.0f);

						glTexCoord2f((GLfloat)qtws[*ch],(GLfloat)qths[*ch]);
						glVertex2f((GLfloat)qvws[*ch],0.0f);

						glTexCoord2f((GLfloat)qtws[*ch],0.0f);
						glVertex2f((GLfloat)qvws[*ch],(GLfloat)qvhs[*ch]);
					glEnd();
				glPopMatrix();
				glTranslatef((GLfloat)wids[*ch],0.0f,0.0f);
			}
		glPopMatrix();
	glPopAttrib();
}