SubPolygon.h File Reference

A class for handling sub-polygons. Each sub-polygon is a continuos, closed set of edges. More...

Classes
class	PolygonEdge
	A polygon edge. More...
class	PolygonScanEdge
	A more optimized representation of a polygon edge. More...
class	VertexData
	A class for holding processing data regarding the vertex. More...
class	SubPolygon
	A class for handling sub-polygons. Each sub-polygon is a continuos, closed set of edges. More...
Defines
#define	USE_ASM_OPTIMIZATIONS
#define	CLIP_SUM_SHIFT   8
#define	CLIP_UNION_SHIFT   4
#define	SLOPE_FIX_SHIFT   8
#define	SLOPE_FIX_STEP   (1 << SLOPE_FIX_SHIFT)
#define	SLOPE_FIX_MASK   (SLOPE_FIX_STEP - 1)
#define	SLOPE_FIX_SCANLINES   (1 << (SLOPE_FIX_SHIFT - SUBPIXEL_SHIFT))
#define	SLOPE_FIX_SCANLINE_MASK   (SLOPE_FIX_SCANLINES - 1)
Enumerations
enum	POLYGON_CLIP_FLAGS {   POLYGON_CLIP_NONE = 0x00, POLYGON_CLIP_LEFT = 0x01, POLYGON_CLIP_RIGHT = 0x02, POLYGON_CLIP_TOP = 0x04,   POLYGON_CLIP_BOTTOM = 0x08 }
Functions
int	rationalToIntRoundDown (RATIONAL a)
	Converts rational to int using direct asm.
int	rationalToFixed (RATIONAL a)
	The rational to fixed conversion is implemented with asm for performance reasons.
void	setRoundDownMode ()
	Sets the FPU round down mode to correct value for the asm conversion routines.

---

Detailed Description

A class for handling sub-polygons. Each sub-polygon is a continuos, closed set of edges.

Scanline edge-flag algorithm for antialiasing
Copyright (c) 2005-2007 Kiia Kallio

http://mlab.uiah.fi/~kkallio/antialiasing/

This code is distributed under the three-clause BSD license. Read the LICENSE file or visit the URL above for details.

Id

Date

Revision

---

Define Documentation

#define CLIP_SUM_SHIFT   8

#define CLIP_UNION_SHIFT   4

#define SLOPE_FIX_MASK   (SLOPE_FIX_STEP - 1)

#define SLOPE_FIX_SCANLINE_MASK   (SLOPE_FIX_SCANLINES - 1)

#define SLOPE_FIX_SCANLINES   (1 << (SLOPE_FIX_SHIFT - SUBPIXEL_SHIFT))

#define SLOPE_FIX_SHIFT   8

Fixed point math inevitably introduces rounding error to the DDA. The error is fixed every now and then by a separate fix value. The defines below set these.

#define SLOPE_FIX_STEP   (1 << SLOPE_FIX_SHIFT)

#define USE_ASM_OPTIMIZATIONS

---

Enumeration Type Documentation

enum POLYGON_CLIP_FLAGS

Enumerator: POLYGON_CLIP_NONE  POLYGON_CLIP_LEFT  POLYGON_CLIP_RIGHT  POLYGON_CLIP_TOP  POLYGON_CLIP_BOTTOM

---

Function Documentation

int rationalToFixed (  RATIONAL  a  )  [inline]

The rational to fixed conversion is implemented with asm for performance reasons.

int rationalToIntRoundDown (  RATIONAL  a  )  [inline]

Converts rational to int using direct asm. Typical conversions using _ftol are slow on Pentium 4, as _ftol sets the control state of the fpu unit. Also, we need a special rounding operation that rounds down, not towards zero. Therefore we use asm here. This requires that the rounding mode is set to round down by calling _controlfp(_MCW_RC,_RC_DOWN). The state of the control mode is thread specific, so other applications won't mix with this.

void setRoundDownMode (   )  [inline]

Sets the FPU round down mode to correct value for the asm conversion routines.

---