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#ifndef _FTGL_H
#define _FTGL_H
#include <ft2build.h>
#include FT_FREETYPE_H
struct _FTGL_Glyph;
typedef struct _FTGL_Font {
unsigned int texture; // OpenGL texture ID
int texture_size; // current texture size
long height; // font height (distance between baselines)
long ascent; // max dist. between baseline and glyph top
long descent; // max dist. between baseline and glyph bottom
FT_Face face; // the Freetype face object
int use_kerning; // whether the font uses kerning
// private part starts here
struct _FTGL_Glyph *glyph; // rendered glyph data
int num_glyphs; // n.o. rendered glyphs
int num_allocated_glyphs; // size of the glyph array
int pen_x, pen_y; // glyph renderer state (current pen position)
unsigned char* texture_data; // glyph renderer state (font texture image)
} FTGL_Font;
/**
* creates a new FTGL_Font object.
*
* FTGL_Font keeps an OpenGL texture that contains glyphs from a font face,
* and can use this texture to render a string in OpenGL.
*
* 'face' is the Freetype face which will be rendered. It should already have
* a size (use something like FT_Set_Char_Size(face, 0, size*64, 0, 96)).
*
* 'initial_texture_size' is the initial size of the texture. (It must be a
* power of two.) If the texture isn't big enough for all required glyphs,
* it'll automatically grow. (This is an expensive operation, and textures can
* be used more effectively when already created with the correct size.)
* You can query the current texture size with font->texture_size.
*
* Kerning is used if 'use_kerning' is true and the face supports it.
*
* The only things FTGL does with textures is glBindTexture and glTexImage2D.
* Creating and deleting textures must be done by you.
*
* As a side effect, this function changes current bound texture to
* 'texture_id'.
*
* This function renders all ASCII characters. If the printed strings contain
* Unicode, you must FTGL_Prepare each string to render them.
*
* This function returns NULL in case of errors.
*/
FTGL_Font* FTGL_Create(FT_Face face, int initial_texture_size, unsigned int texture_id, int use_kerning);
/**
* destroys a FTGL_Font object.
*
* This doesn't destroy the OpenGL texture nor the FT_Face object.
*/
void FTGL_Destroy(FTGL_Font* font);
/**
* prints a string.
*
* It prints the string using OpenGL at the current position (0,0,0).
*
* This doesn't use any Freetype functions. All glyphs in the string must
* already be rendered and inside the font->glyph array. Use FTGL_Prepare to
* make sure all characters in the string are already rendered.
*
* 'string' should be in UTF-8. Non-ASCII characters will be converted to UCS
* automatically.
*
* If 'underline' is 0, the string isn't underlined. If 'underline' is 1, the
* whole string is underlined. If 'underline' is an ASCII code (other than 0
* and 1), it's a special character that, when found in 'string', underlines
* the following glyph.
*
* As a side effect, this function changes current bound texture to the font
* texture, and translates the current GL position to the end of the string.
*
* This function might not work correctly if the following is not enabled:
* glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA,
* GL_ONE_MINUS_SRC_ALPHA);
*/
void FTGL_Print(FTGL_Font* font, const char* string, int underline);
/**
* prepares a string for printing.
*
* If the string contains Unicode glyphs that weren't rendered yet, this
* renders them and stores them in the font texture (expanding it if it isn't
* big enough).
*
* Every string should be FTGL_Prepare'd at least once before printing. It
* isn't needed to call FTGL_Prepare every frame, however.
*
* On success, FTGL_Prepare returns the string's width. (Thus, it can be used
* to measure string sizes before printing them.) If it returns -1, a memory
* error occured and the font is invalid (it can't be used anymore).
*/
long FTGL_Prepare(FTGL_Font* font, const char* string);
#endif
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