3D Font Text APIs

Detailed Description

Implements 3D APIs for font text used by applications.

For details on the original implementation, see: http://www.opengl.org/code/detail/texfont_glut_based_library_for_creating_fonts_out_of_textures.

The OpenGL ES 2.0 NVTexfont library has been expanded to include both raster and vector fonts. The main functions are described below.

Macros
#define	TXF_FORMAT_BYTE   0
#define	TXF_FORMAT_BITMAP   1

Typedefs
typedef void *	NVTexfontContext
typedef struct _NVTexfontRasterFont	NVTexfontRasterFont
typedef struct _NVTexfontVectorFont	NVTexfontVectorFont

Enumerations
enum	NVTexfontRasterFontName {   NV_TEXFONT_DEFAULT = 0,   NV_TEXFONT_HELVETICA = 0 }
enum	NVTexfontVectorFontName {   NV_VECTOR_TEXFONT_DEFAULT = 0,   NV_VECTOR_TEXFONT_INCONSOLATA = 0 }

Functions
char *	nvtexfontErrorString (void)
NVTexfontContext	nvtexfontAllocContext (void)
	Allocates a handle for an NVTexfont context. More...
void	nvtexfontFreeContext (NVTexfontContext tfc)
	Frees the specified NVTexfont context handle. More...
void	nvtexfontSetContextPos (NVTexfontContext tfc, float x, float y)
	Sets the x,y attributes for the NVTexfont context tfc. More...
void	nvtexfontSetContextScale (NVTexfontContext tfc, float scaleX, float scaleY)
	Sets the x,y attributes for the NVTexfont context tfc. More...
void	nvtexfontSetContextColor (NVTexfontContext tfc, float r, float g, float b)

Raster Font Functions
int	nvtexfontInRasterFont (NVTexfontRasterFont *txf, int c)
NVTexfontRasterFont *	nvtexfontInitRasterFont (NVTexfontRasterFontName font, GLuint texobj, GLboolean setupMipmaps, GLenum minFilter, GLenum magFilter)
	Initializes an NVTexfontRasterFont. More...
void	nvtexfontUnloadRasterFont (NVTexfontRasterFont *txf)
	Frees textures used by the font txf. More...
void	nvtexfontRenderString_All (NVTexfontRasterFont *txf, char *string, float x, float y, float scaleX, float scaleY, float r, float g, float b)
	Renders the specified null-terminated string by using the NVTexfont txf. More...
void	nvtexfontRenderString_Pos (NVTexfontRasterFont *txf, NVTexfontContext tfc, char *string, float x, float y)
	Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted. More...
void	nvtexfontRenderString (NVTexfontRasterFont *txf, NVTexfontContext tfc, char *string)
void	nvtexfontGetStringMetrics (NVTexfontRasterFont *txf, char *string, int len, int *width, int *max_ascent, int *max_descent)

Vector Font Functions
int	nvtexfontInVectorFont (NVTexfontVectorFont *vtf, int c)
NVTexfontVectorFont *	nvtexfontInitVectorFont (NVTexfontVectorFontName font, GLboolean antialias, GLboolean use_vbo)
	Initialize an NVTexfontVectorFont. More...
void	nvtexfontUnloadVectorFont (NVTexfontVectorFont *vtf)
	Frees resources used by the vector font vtf, including the VBO if used. More...
void	nvtexfontRenderVecString_All (NVTexfontVectorFont *vtf, char *string, float x, float y, float scaleX, float scaleY, float r, float g, float b)
	Renders the specified null-terminated string by using the NVTexfontVectorFont vtf. More...
void	nvtexfontRenderVecString_Pos (NVTexfontVectorFont *vtf, NVTexfontContext tfc, char *string, float x, float y)
	Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted. More...
void	nvtexfontRenderVecString (NVTexfontVectorFont *vtf, NVTexfontContext tfc, char *string)
	Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted. More...

Macro Definition Documentation

#define TXF_FORMAT_BITMAP   1

Definition at line 59 of file nvtexfont.h.

#define TXF_FORMAT_BYTE   0

Definition at line 58 of file nvtexfont.h.

Typedef Documentation

typedef void* NVTexfontContext

Definition at line 61 of file nvtexfont.h.

typedef struct _NVTexfontRasterFont NVTexfontRasterFont

Definition at line 73 of file nvtexfont.h.

typedef struct _NVTexfontVectorFont NVTexfontVectorFont

Definition at line 74 of file nvtexfont.h.

Enumeration Type Documentation

enum NVTexfontRasterFontName

Enumerator
NV_TEXFONT_DEFAULT
NV_TEXFONT_HELVETICA

Definition at line 63 of file nvtexfont.h.

enum NVTexfontVectorFontName

Enumerator
NV_VECTOR_TEXFONT_DEFAULT
NV_VECTOR_TEXFONT_INCONSOLATA

Definition at line 68 of file nvtexfont.h.

Function Documentation

NVTexfontContext nvtexfontAllocContext

(

void

)

Allocates a handle for an NVTexfont context.

Default settings are held for each context.

char* nvtexfontErrorString

(

void

)

void nvtexfontFreeContext

(

NVTexfontContext

tfc

)

Frees the specified NVTexfont context handle.

void nvtexfontGetStringMetrics	(	NVTexfontRasterFont *	txf,
		char *	string,
		int	len,
		int *	width,
		int *	max_ascent,
		int *	max_descent
	)

NVTexfontRasterFont* nvtexfontInitRasterFont	(	NVTexfontRasterFontName	font,
		GLuint	texobj,
		GLboolean	setupMipmaps,
		GLenum	minFilter,
		GLenum	magFilter
	)

Initializes an NVTexfontRasterFont.

By default, NVTexfont supports only the NV_TEXFONT_HELVETICA font. NV_TEXFONT_DEFAULT is the same as NV_TEXFONT_HELVETICA. More may be compiled into the library, at the cost of making the library larger.

Parameters

font	Specifies the raster font to initialize.
texobj	Specifies the texture object. If 0, a name is generated using the OpenGL 4 glGenTextures function.
setupMipmaps	Specifies the MIP maps to accompany this texture.
minFilter	Specifies the minimum filter for the MIP maps.
magFilter	Specifies the maximum filter for the MIP maps.

NVTexfontVectorFont* nvtexfontInitVectorFont	(	NVTexfontVectorFontName	font,
		GLboolean	antialias,
		GLboolean	use_vbo
	)

Initialize an NVTexfontVectorFont.

By default, NVTexfont supports one vector font: NV_VECTOR_TEXFONT_INCONSOLATA. NV_TEXFONT_DEFAULT is the same as NV_VECTOR_TEXFONT_INCONSOLATA.

Parameters

font	Specifies the vector font to initialize.
antialias	Specifies whether the text should be antialiased when drawn.
use_vbo	Specifies whether a vertex buffer object (VBO) should be used to speed up the rendering.

int nvtexfontInRasterFont	(	NVTexfontRasterFont *	txf,
		int	c
	)

int nvtexfontInVectorFont	(	NVTexfontVectorFont *	vtf,
		int	c
	)

void nvtexfontRenderString	(	NVTexfontRasterFont *	txf,
		NVTexfontContext	tfc,
		char *	string
	)

void nvtexfontRenderString_All	(	NVTexfontRasterFont *	txf,
		char *	string,
		float	x,
		float	y,
		float	scaleX,
		float	scaleY,
		float	r,
		float	g,
		float	b
	)

Renders the specified null-terminated string by using the NVTexfont txf.

The text gets drawn at position (x, y) on the screen with the relevant scale and the color (r,g,b).

The size of the text is one unit per font pixel. This is scaled so that the height of the text is 1/10th the height of the screen when scale = 1.0. txfGetStringMetrics may be used to get the width, maximum ascent from baseline, and maximum descent from baseline.

Parameters

txf	A pointer to the texture font.
string	A pointer to the string to render.
x	The x position at which to render.
y	The y position at which to render.
scaleX	The X scale.
scaleY	The Y scale.
r	The red value.
g	The green value.
b	The blue value.

void nvtexfontRenderString_Pos	(	NVTexfontRasterFont *	txf,
		NVTexfontContext	tfc,
		char *	string,
		float	x,
		float	y
	)

Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted.

Parameters

txf	A pointer to the texture font.
tfc	The texture font context.
string	A pointer to the string to render.
x	The x position at which to draw.
y	The y position at which to draw.

void nvtexfontRenderVecString	(	NVTexfontVectorFont *	vtf,
		NVTexfontContext	tfc,
		char *	string
	)

Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted.

Parameters

vtf	A pointer to the vector font to use when rendering.
tfc	The texture font context.
string	A pointer to the string to render.

void nvtexfontRenderVecString_All	(	NVTexfontVectorFont *	vtf,
		char *	string,
		float	x,
		float	y,
		float	scaleX,
		float	scaleY,
		float	r,
		float	g,
		float	b
	)

Renders the specified null-terminated string by using the NVTexfontVectorFont vtf.

A scale of 1.0 is equivalent to 1/10 the height of the viewport. The text gets drawn in the color specified by (r,g,b).

Parameters

vtf	A pointer to the vector font to use when rendering.
string	A pointer to the string to render.
scaleX	The scale for X.
scaleY	The scale for Y.
x	The x position at which to draw, after being adjusted for scaleX.
y	The y position at which to draw, after being adjusted for scaleY.
r	The red value.
g	The green value.
b	The blue value.

void nvtexfontRenderVecString_Pos	(	NVTexfontVectorFont *	vtf,
		NVTexfontContext	tfc,
		char *	string,
		float	x,
		float	y
	)

Renders the specified null-terminated string as above but uses the position/scale/color from the NVTexfontContext where omitted.

Parameters

vtf	A pointer to the vector font to use when rendering.
tfc	The texture font context.
string	A pointer to the string to render.
x	The x position at which to draw.
y	The y position at which to draw.

void nvtexfontSetContextColor	(	NVTexfontContext	tfc,
		float	r,
		float	g,
		float	b
	)

void nvtexfontSetContextPos	(	NVTexfontContext	tfc,
		float	x,
		float	y
	)

Sets the x,y attributes for the NVTexfont context tfc.

Parameters

tfc	Specifies the NVTexfont context for which to set attributes.
x	Specifies the x attribute to set.
y	Specifies the y attribute to set.

void nvtexfontSetContextScale	(	NVTexfontContext	tfc,
		float	scaleX,
		float	scaleY
	)

Sets the x,y attributes for the NVTexfont context tfc.

Parameters

tfc	Specifies the NVTexfont context for which to set attributes.
scaleX	Specifies the scale value for X.
scaleY	Specifies the scale value for Y.

void nvtexfontUnloadRasterFont

(

NVTexfontRasterFont *

txf

)

Frees textures used by the font txf.

Parameters

txf	A pointer to the textures to free.

void nvtexfontUnloadVectorFont

(

NVTexfontVectorFont *

vtf

)

Frees resources used by the vector font vtf, including the VBO if used.

Parameters

vtf	A pointer to the vector font resources to free.