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65fea56f17cd614bc8908264df980a62e1931468vboxsync * Created by Brian Kelleher; Oct 1985
65fea56f17cd614bc8908264df980a62e1931468vboxsync * Include file for filled polygon routines.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * These are the data structures needed to scan
65fea56f17cd614bc8908264df980a62e1931468vboxsync * convert regions. Two different scan conversion
65fea56f17cd614bc8908264df980a62e1931468vboxsync * methods are available -- the even-odd method, and
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the winding number method.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * The even-odd rule states that a point is inside
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the polygon if a ray drawn from that point in any
65fea56f17cd614bc8908264df980a62e1931468vboxsync * direction will pass through an odd number of
65fea56f17cd614bc8908264df980a62e1931468vboxsync * path segments.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * By the winding number rule, a point is decided
65fea56f17cd614bc8908264df980a62e1931468vboxsync * to be inside the polygon if a ray drawn from that
65fea56f17cd614bc8908264df980a62e1931468vboxsync * point in any direction passes through a different
65fea56f17cd614bc8908264df980a62e1931468vboxsync * number of clockwise and counter-clockwise path
65fea56f17cd614bc8908264df980a62e1931468vboxsync * segments.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * These data structures are adapted somewhat from
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the algorithm in (Foley/Van Dam) for scan converting
65fea56f17cd614bc8908264df980a62e1931468vboxsync * polygons.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * The basic algorithm is to start at the top (smallest y)
65fea56f17cd614bc8908264df980a62e1931468vboxsync * of the polygon, stepping down to the bottom of
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the polygon by incrementing the y coordinate. We
65fea56f17cd614bc8908264df980a62e1931468vboxsync * keep a list of edges which the current scanline crosses,
65fea56f17cd614bc8908264df980a62e1931468vboxsync * sorted by x. This list is called the Active Edge Table (AET)
65fea56f17cd614bc8908264df980a62e1931468vboxsync * As we change the y-coordinate, we update each entry in
65fea56f17cd614bc8908264df980a62e1931468vboxsync * in the active edge table to reflect the edges new xcoord.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * This list must be sorted at each scanline in case
65fea56f17cd614bc8908264df980a62e1931468vboxsync * two edges intersect.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * We also keep a data structure known as the Edge Table (ET),
65fea56f17cd614bc8908264df980a62e1931468vboxsync * which keeps track of all the edges which the current
65fea56f17cd614bc8908264df980a62e1931468vboxsync * scanline has not yet reached. The ET is basically a
65fea56f17cd614bc8908264df980a62e1931468vboxsync * list of ScanLineList structures containing a list of
65fea56f17cd614bc8908264df980a62e1931468vboxsync * edges which are entered at a given scanline. There is one
65fea56f17cd614bc8908264df980a62e1931468vboxsync * ScanLineList per scanline at which an edge is entered.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * When we enter a new edge, we move it from the ET to the AET.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * From the AET, we can implement the even-odd rule as in
65fea56f17cd614bc8908264df980a62e1931468vboxsync * The winding number rule is a little trickier. We also
65fea56f17cd614bc8908264df980a62e1931468vboxsync * keep the EdgeTableEntries in the AET linked by the
65fea56f17cd614bc8908264df980a62e1931468vboxsync * nextWETE (winding EdgeTableEntry) link. This allows
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the edges to be linked just as before for updating
65fea56f17cd614bc8908264df980a62e1931468vboxsync * purposes, but only uses the edges linked by the nextWETE
65fea56f17cd614bc8908264df980a62e1931468vboxsync * link as edges representing spans of the polygon to
65fea56f17cd614bc8908264df980a62e1931468vboxsync * drawn (as with the even-odd rule).
65fea56f17cd614bc8908264df980a62e1931468vboxsync * for the winding number rule
65fea56f17cd614bc8908264df980a62e1931468vboxsync BRESINFO bres; /* Bresenham info to run the edge */
65fea56f17cd614bc8908264df980a62e1931468vboxsync struct _EdgeTableEntry *next; /* next in the list */
65fea56f17cd614bc8908264df980a62e1931468vboxsync struct _EdgeTableEntry *back; /* for insertion sort */
65fea56f17cd614bc8908264df980a62e1931468vboxsync struct _EdgeTableEntry *nextWETE; /* for winding num rule */
65fea56f17cd614bc8908264df980a62e1931468vboxsynctypedef struct {
65fea56f17cd614bc8908264df980a62e1931468vboxsync * Here is a struct to help with storage allocation
65fea56f17cd614bc8908264df980a62e1931468vboxsync * so we can allocate a big chunk at a time, and then take
65fea56f17cd614bc8908264df980a62e1931468vboxsync * pieces from this heap when we need to.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * number of points to buffer before sending them off
65fea56f17cd614bc8908264df980a62e1931468vboxsync * to scanlines() : Must be an even number
65fea56f17cd614bc8908264df980a62e1931468vboxsync * a few macros for the inner loops of the fill code where
65fea56f17cd614bc8908264df980a62e1931468vboxsync * performance considerations don't allow a procedure call.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * Evaluate the given edge at the given scanline.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * If the edge has expired, then we leave it and fix up
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the active edge table; otherwise, we increment the
65fea56f17cd614bc8908264df980a62e1931468vboxsync * x value to be ready for the next scanline.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * The winding number rule is in effect, so we must notify
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the caller when the edge has been removed so he
65fea56f17cd614bc8908264df980a62e1931468vboxsync * can reorder the Winding Active Edge Table.
65fea56f17cd614bc8908264df980a62e1931468vboxsync#define EVALUATEEDGEWINDING(pAET, pPrevAET, y, fixWAET) { \
65fea56f17cd614bc8908264df980a62e1931468vboxsync * Evaluate the given edge at the given scanline.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * If the edge has expired, then we leave it and fix up
65fea56f17cd614bc8908264df980a62e1931468vboxsync * the active edge table; otherwise, we increment the
65fea56f17cd614bc8908264df980a62e1931468vboxsync * x value to be ready for the next scanline.
65fea56f17cd614bc8908264df980a62e1931468vboxsync * The even-odd rule is in effect.
65fea56f17cd614bc8908264df980a62e1931468vboxsyncextern _X_EXPORT Bool miCreateETandAET(int /*count */ ,
65fea56f17cd614bc8908264df980a62e1931468vboxsyncextern _X_EXPORT void miloadAET(EdgeTableEntry * /*AET*/, EdgeTableEntry * /*ETEs */
65fea56f17cd614bc8908264df980a62e1931468vboxsyncextern _X_EXPORT void micomputeWAET(EdgeTableEntry * /*AET*/);
65fea56f17cd614bc8908264df980a62e1931468vboxsyncextern _X_EXPORT int miInsertionSort(EdgeTableEntry * /*AET*/);
65fea56f17cd614bc8908264df980a62e1931468vboxsyncextern _X_EXPORT void miFreeStorage(ScanLineListBlock * /*pSLLBlock */