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OGLFT::Polygonal Class Reference

This is the base class of the polygonal styles: outline, filled and solid. More...

#include <OGLFT.h>

Inheritance diagram for OGLFT::Polygonal::

List of all members.

Public Methods
	Polygonal (const char *filename, float point_size=12, FT_UInt resolution=100)
	Polygonal (FT_Face face, float point_size=12, FT_UInt resolution=100)
virtual	~Polygonal (void)
void	setTessellationSteps (unsigned int tessellation_steps)
unsigned int	tessellationSteps (void) const
void	setCharacterRotationX (GLfloat character_rotation_x)
void	setCharacterRotationY (GLfloat character_rotation_y)
void	setCharacterRotationZ (GLfloat character_rotation_z)
GLfloat	characterRotationX (void) const
GLfloat	characterRotationY (void) const
GLfloat	characterRotationZ (void) const
void	setColorTess (ColorTess *color_tess)
ColorTess*	colorTess (void) const
void	setTextureTess (TextureTess *texture_tess)
TextureTess*	textureTess (void) const
double	height (void) const
BBox	measure (unsigned char c)
BBox	measure (const QChar c)
BBox	measure (const char *s)
BBox	measure (const QString &format, double number)
Protected Types
typedef std::list< VertexInfo* >	VertexInfoList
	Normally, we will consider a list of vertices.
typedef VertexInfoList::const_iterator	VILCI
	A convenience definition of the iterator over the list of vertices.
typedef VertexInfoList::iterator	VILI
	A convenience definition of the iterator over the list of vertices.
Protected Methods
void	clearCaches (void)
	The different styles have different caching needs (well, really only the texture style currently has more than the display list cache).
Protected Attributes
struct {
bool   active_
GLfloat   x_
GLfloat   y_
GLfloat   z_
}	character_rotation_
	Angle of rotation of characters relative to text orientation.
unsigned int	tessellation_steps_
	The tessellation of curves is pretty crude; regardless of length, use the same number of increments (and as near as I can tell, this is more than sufficient unless the glyph takes up the whole screen).
double	delta_
	When curves are tessellated, we use the forward difference algorithm from Foley and van Dam for parametric curves (pg. 511 of 2nd Ed. in C). So, the step size, delta, is in the parametric variable which is always on the interval [0,1]. Therefore, delta = 1/tessellation_steps.
double	delta2_
	When curves are tessellated, we use the forward difference algorithm from Foley and van Dam for parametric curves (pg. 511 of 2nd Ed. in C). So, the step size, delta, is in the parametric variable which is always on the interval [0,1]. Therefore, delta = 1/tessellation_steps.
double	delta3_
	When curves are tessellated, we use the forward difference algorithm from Foley and van Dam for parametric curves (pg. 511 of 2nd Ed. in C). So, the step size, delta, is in the parametric variable which is always on the interval [0,1]. Therefore, delta = 1/tessellation_steps.
double	vector_scale_
	For vector rendition modes, FreeType is allowed to generate the lines and arcs at the original face definition resolution. To get to the proper glyph size, the vertices are scaled before they're passed to the GLU tessellation routines.
FT_Outline_Funcs	interface_
	Callbacks for FreeType glyph decomposition into outlines.
VertexInfo	last_vertex_
VertexInfoList	vertices_
bool	contour_open_
	As GLU tessellation proceeds, new contours open with every call to moveTo.
ColorTess*	color_tess_
	The user can provide a ColorTess object which computes a color for each tesselated vertex.
TextureTess*	texture_tess_
	The user can provide a TextureTess object which computes texture coordinates for each tesselated vertex.
Static Protected Attributes
const unsigned int	DEFAULT_TESSELLATION_STEPS = 4
	Default number of steps to break TrueType and Type1 arcs into. (Note: this looks good to me, anyway).

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Detailed Description

This is the base class of the polygonal styles: outline, filled and solid.

In the polygonal styles, the detailed geometric outlines of the glyphs are extracted from the font file and rendered as polygons.

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Constructor & Destructor Documentation

OGLFT::Polygonal::Polygonal ( const char * filename, float point_size = 12, FT_UInt resolution = 100 )

Parameters: file   the filename which contains the font face. point_size   the initial point size of the font to generate. A point is essentially 1/72th of an inch. Defaults to 12. resolution   the pixel density of the display in dots per inch (DPI). Defaults to 100 DPI.

OGLFT::Polygonal::Polygonal ( FT_Face face, float point_size = 12, FT_UInt resolution = 100 )

Parameters: face   open Freetype FT_Face. point_size   the initial point size of the font to generate. A point is essentially 1/72th of an inch. Defaults to 12. resolution   the pixel density of the display in dots per inch (DPI). Defaults to 100 DPI.

OGLFT::Polygonal::~Polygonal ( void ) [virtual]

The Polygonal destructor doesn't do anything in particular.

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Member Function Documentation

GLfloat OGLFT::Polygonal::characterRotationX ( void ) const [inline]

Returns: the character rotation in the X direction.

GLfloat OGLFT::Polygonal::characterRotationY ( void ) const [inline]

Returns: the character rotation in the Y direction.

GLfloat OGLFT::Polygonal::characterRotationZ ( void ) const [inline, virtual]

Returns: the character rotation in the Z direction. Reimplemented from OGLFT::Face.

ColorTess * OGLFT::Polygonal::colorTess ( void ) const [inline]

Returns: the color tesselation object.

double OGLFT::Polygonal::height ( void ) const [virtual]

Returns: the height (i.e., line spacing) at the current character size. Reimplemented from OGLFT::Face.

BBox OGLFT::Polygonal::measure ( const QString & format, double number ) [inline, virtual]

Implement measuring a formatted number Parameters: format   the format string number   to value to format Returns: the bounding box of the formatted number Reimplemented from OGLFT::Face.

BBox OGLFT::Polygonal::measure ( const char * s ) [inline, virtual]

Measure a string of characters. Note: currently, this merely calls Face's measure routine. Parameters: s   string of (latin1) characters to measure Returns: the bounding box of s. Reimplemented from OGLFT::Face.

BBox OGLFT::Polygonal::measure ( const QChar c ) [virtual]

Implement measuring a character in a polygonal face. Parameters: c   the (UNICODE) character to measure Returns: the bounding box of c. Reimplemented from OGLFT::Face.

BBox OGLFT::Polygonal::measure ( unsigned char c ) [virtual]

Implement measuring a character in a polygonal face. Parameters: c   the (latin1) character to measure Returns: the bounding box of c. Reimplemented from OGLFT::Face.

void OGLFT::Polygonal::setCharacterRotationX ( GLfloat character_rotation_x )

Set the individual character rotation in the X direction. Parameters: character_rotation_x   angle in degrees of the X rotation.

void OGLFT::Polygonal::setCharacterRotationY ( GLfloat character_rotation_y )

Set the individual character rotation in the Y direction. Parameters: character_rotation_y   angle in degrees of the Y rotation.

void OGLFT::Polygonal::setCharacterRotationZ ( GLfloat character_rotation_z ) [virtual]

Set the individual character rotation in the Z direction. Parameters: character_rotation_z   angle in degrees of the Z rotation. Reimplemented from OGLFT::Face.

void OGLFT::Polygonal::setColorTess ( ColorTess * color_tess )

Set an optional color tesselation object. Each tesselated vertex is passed to this object, which returns a color for that position in space. Parameters: color_tess   the color tesselation object.

void OGLFT::Polygonal::setTessellationSteps ( unsigned int tessellation_steps )

TrueType and Type1 files describe the boundaries of glyphs with quadratic and cubic curves, respectively. Since OpenGL can only really draw straight lines, these curves have to be tessellated. The number of steps used is fixed for all glyphs in the face, but can be changed through this method. Other notes: This value is only applicable for Outline, Filled and Solid styles. Changing this value invalidates any cached display lists for glyphs in this face. Parameters: tessellation_steps   the number of steps to tessellate each curved segment of a glyph outline.

void OGLFT::Polygonal::setTextureTess ( TextureTess * texture_tess )

Set an optional texture coordinate tesselation object. Each tessellated vertex is passed to this object, which returns texture coordinates for that position in space. Parameters: texture_tess   the texture coordinate tesselation object.

unsigned int OGLFT::Polygonal::tessellationSteps ( void ) const [inline]

Returns: the number of steps used to tessellate curves in the polygonal font types.

TextureTess * OGLFT::Polygonal::textureTess ( void ) const [inline]

Returns: the texture coordinate tesselation object.

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Member Data Documentation

VertexInfo OGLFT::Polygonal::last_vertex_ [protected]

Buffers the last control point as the outline of a glyph is decomposed.

VertexInfoList OGLFT::Polygonal::vertices_ [protected]

As curves are decomposed out of the glyph, their vertices are passed along to the GLU tessellation functions. These vertices have to hang around until gluTessContourEnd is called.

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The documentation for this class was generated from the following files:

• OGLFT.h
• OGLFT.cpp

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