mirror of
https://gitlab.gnome.org/GNOME/gtk.git
synced 2024-11-18 17:30:10 +00:00
231 lines
7.0 KiB
C
231 lines
7.0 KiB
C
/* $TOG: mipoly.h /main/6 1998/02/09 14:48:20 kaleb $ */
|
||
/*
|
||
|
||
Copyright 1987, 1998 The Open Group
|
||
|
||
All Rights Reserved.
|
||
|
||
The above copyright notice and this permission notice shall be included
|
||
in all copies or substantial portions of the Software.
|
||
|
||
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
|
||
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
||
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
|
||
IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
|
||
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
|
||
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
|
||
OTHER DEALINGS IN THE SOFTWARE.
|
||
|
||
Except as contained in this notice, the name of The Open Group shall
|
||
not be used in advertising or otherwise to promote the sale, use or
|
||
other dealings in this Software without prior written authorization
|
||
from The Open Group.
|
||
|
||
*/
|
||
|
||
#ifndef MIPOLY_H
|
||
#define MIPOLY_H
|
||
|
||
#include "miscanfill.h"
|
||
|
||
/*
|
||
* fill.h
|
||
*
|
||
* Created by Brian Kelleher; Oct 1985
|
||
*
|
||
* Include file for filled polygon routines.
|
||
*
|
||
* These are the data structures needed to scan
|
||
* convert regions. Two different scan conversion
|
||
* methods are available -- the even-odd method, and
|
||
* the winding number method.
|
||
* The even-odd rule states that a point is inside
|
||
* the polygon if a ray drawn from that point in any
|
||
* direction will pass through an odd number of
|
||
* path segments.
|
||
* By the winding number rule, a point is decided
|
||
* to be inside the polygon if a ray drawn from that
|
||
* point in any direction passes through a different
|
||
* number of clockwise and counter-clockwise path
|
||
* segments.
|
||
*
|
||
* These data structures are adapted somewhat from
|
||
* the algorithm in (Foley/Van Dam) for scan converting
|
||
* polygons.
|
||
* The basic algorithm is to start at the top (smallest y)
|
||
* of the polygon, stepping down to the bottom of
|
||
* the polygon by incrementing the y coordinate. We
|
||
* keep a list of edges which the current scanline crosses,
|
||
* sorted by x. This list is called the Active Edge Table (AET)
|
||
* As we change the y-coordinate, we update each entry in
|
||
* in the active edge table to reflect the edges new xcoord.
|
||
* This list must be sorted at each scanline in case
|
||
* two edges intersect.
|
||
* We also keep a data structure known as the Edge Table (ET),
|
||
* which keeps track of all the edges which the current
|
||
* scanline has not yet reached. The ET is basically a
|
||
* list of ScanLineList structures containing a list of
|
||
* edges which are entered at a given scanline. There is one
|
||
* ScanLineList per scanline at which an edge is entered.
|
||
* When we enter a new edge, we move it from the ET to the AET.
|
||
*
|
||
* From the AET, we can implement the even-odd rule as in
|
||
* (Foley/Van Dam).
|
||
* The winding number rule is a little trickier. We also
|
||
* keep the EdgeTableEntries in the AET linked by the
|
||
* nextWETE (winding EdgeTableEntry) link. This allows
|
||
* the edges to be linked just as before for updating
|
||
* purposes, but only uses the edges linked by the nextWETE
|
||
* link as edges representing spans of the polygon to
|
||
* drawn (as with the even-odd rule).
|
||
*/
|
||
|
||
/*
|
||
* for the winding number rule
|
||
*/
|
||
#define CLOCKWISE 1
|
||
#define COUNTERCLOCKWISE -1
|
||
|
||
typedef struct _EdgeTableEntry {
|
||
int ymax; /* ycoord at which we exit this edge. */
|
||
BRESINFO bres; /* Bresenham info to run the edge */
|
||
struct _EdgeTableEntry *next; /* next in the list */
|
||
struct _EdgeTableEntry *back; /* for insertion sort */
|
||
struct _EdgeTableEntry *nextWETE; /* for winding num rule */
|
||
int ClockWise; /* flag for winding number rule */
|
||
} EdgeTableEntry;
|
||
|
||
|
||
typedef struct _ScanLineList{
|
||
int scanline; /* the scanline represented */
|
||
EdgeTableEntry *edgelist; /* header node */
|
||
struct _ScanLineList *next; /* next in the list */
|
||
} ScanLineList;
|
||
|
||
|
||
typedef struct {
|
||
int ymax; /* ymax for the polygon */
|
||
int ymin; /* ymin for the polygon */
|
||
ScanLineList scanlines; /* header node */
|
||
} EdgeTable;
|
||
|
||
|
||
/*
|
||
* Here is a struct to help with storage allocation
|
||
* so we can allocate a big chunk at a time, and then take
|
||
* pieces from this heap when we need to.
|
||
*/
|
||
#define SLLSPERBLOCK 25
|
||
|
||
typedef struct _ScanLineListBlock {
|
||
ScanLineList SLLs[SLLSPERBLOCK];
|
||
struct _ScanLineListBlock *next;
|
||
} ScanLineListBlock;
|
||
|
||
/*
|
||
* number of points to buffer before sending them off
|
||
* to scanlines() : Must be an even number
|
||
*/
|
||
#define NUMPTSTOBUFFER 200
|
||
|
||
|
||
/*
|
||
*
|
||
* a few macros for the inner loops of the fill code where
|
||
* performance considerations don't allow a procedure call.
|
||
*
|
||
* Evaluate the given edge at the given scanline.
|
||
* If the edge has expired, then we leave it and fix up
|
||
* the active edge table; otherwise, we increment the
|
||
* x value to be ready for the next scanline.
|
||
* The winding number rule is in effect, so we must notify
|
||
* the caller when the edge has been removed so he
|
||
* can reorder the Winding Active Edge Table.
|
||
*/
|
||
#define EVALUATEEDGEWINDING(pAET, pPrevAET, y, fixWAET) { \
|
||
if (pAET->ymax == y) { /* leaving this edge */ \
|
||
pPrevAET->next = pAET->next; \
|
||
pAET = pPrevAET->next; \
|
||
fixWAET = 1; \
|
||
if (pAET) \
|
||
pAET->back = pPrevAET; \
|
||
} \
|
||
else { \
|
||
BRESINCRPGONSTRUCT(pAET->bres); \
|
||
pPrevAET = pAET; \
|
||
pAET = pAET->next; \
|
||
} \
|
||
}
|
||
|
||
|
||
/*
|
||
* Evaluate the given edge at the given scanline.
|
||
* If the edge has expired, then we leave it and fix up
|
||
* the active edge table; otherwise, we increment the
|
||
* x value to be ready for the next scanline.
|
||
* The even-odd rule is in effect.
|
||
*/
|
||
#define EVALUATEEDGEEVENODD(pAET, pPrevAET, y) { \
|
||
if (pAET->ymax == y) { /* leaving this edge */ \
|
||
pPrevAET->next = pAET->next; \
|
||
pAET = pPrevAET->next; \
|
||
if (pAET) \
|
||
pAET->back = pPrevAET; \
|
||
} \
|
||
else { \
|
||
BRESINCRPGONSTRUCT(pAET->bres); \
|
||
pPrevAET = pAET; \
|
||
pAET = pAET->next; \
|
||
} \
|
||
}
|
||
|
||
/* mipolyutil.c */
|
||
|
||
extern gboolean miInsertEdgeInET(
|
||
#if NeedFunctionPrototypes
|
||
EdgeTable * /*ET*/,
|
||
EdgeTableEntry * /*ETE*/,
|
||
int /*scanline*/,
|
||
ScanLineListBlock ** /*SLLBlock*/,
|
||
int * /*iSLLBlock*/
|
||
#endif
|
||
);
|
||
|
||
extern gboolean miCreateETandAET(
|
||
#if NeedFunctionPrototypes
|
||
int /*count*/,
|
||
GdkPoint* /*pts*/,
|
||
EdgeTable * /*ET*/,
|
||
EdgeTableEntry * /*AET*/,
|
||
EdgeTableEntry * /*pETEs*/,
|
||
ScanLineListBlock * /*pSLLBlock*/
|
||
#endif
|
||
);
|
||
|
||
extern void miloadAET(
|
||
#if NeedFunctionPrototypes
|
||
EdgeTableEntry * /*AET*/,
|
||
EdgeTableEntry * /*ETEs*/
|
||
#endif
|
||
);
|
||
|
||
extern void micomputeWAET(
|
||
#if NeedFunctionPrototypes
|
||
EdgeTableEntry * /*AET*/
|
||
#endif
|
||
);
|
||
|
||
extern int miInsertionSort(
|
||
#if NeedFunctionPrototypes
|
||
EdgeTableEntry * /*AET*/
|
||
#endif
|
||
);
|
||
|
||
extern void miFreeStorage(
|
||
#if NeedFunctionPrototypes
|
||
ScanLineListBlock * /*pSLLBlock*/
|
||
#endif
|
||
);
|
||
|
||
#endif
|