--- /dev/null
+/* $XConsortium: miscanfill.h,v 1.5 94/04/17 20:27:50 dpw Exp $ */
+/*
+
+Copyright (c) 1987 X Consortium
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+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 X CONSORTIUM 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 X Consortium 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 X Consortium.
+
+*/
+
+
+#ifndef SCANFILLINCLUDED
+#define SCANFILLINCLUDED
+/*
+ * scanfill.h
+ *
+ * Written by Brian Kelleher; Jan 1985
+ *
+ * This file contains a few macros to help track
+ * the edge of a filled object. The object is assumed
+ * to be filled in scanline order, and thus the
+ * algorithm used is an extension of Bresenham's line
+ * drawing algorithm which assumes that y is always the
+ * major axis.
+ * Since these pieces of code are the same for any filled shape,
+ * it is more convenient to gather the library in one
+ * place, but since these pieces of code are also in
+ * the inner loops of output primitives, procedure call
+ * overhead is out of the question.
+ * See the author for a derivation if needed.
+ */
+\f
+
+/*
+ * In scan converting polygons, we want to choose those pixels
+ * which are inside the polygon. Thus, we add .5 to the starting
+ * x coordinate for both left and right edges. Now we choose the
+ * first pixel which is inside the pgon for the left edge and the
+ * first pixel which is outside the pgon for the right edge.
+ * Draw the left pixel, but not the right.
+ *
+ * How to add .5 to the starting x coordinate:
+ * If the edge is moving to the right, then subtract dy from the
+ * error term from the general form of the algorithm.
+ * If the edge is moving to the left, then add dy to the error term.
+ *
+ * The reason for the difference between edges moving to the left
+ * and edges moving to the right is simple: If an edge is moving
+ * to the right, then we want the algorithm to flip immediately.
+ * If it is moving to the left, then we don't want it to flip until
+ * we traverse an entire pixel.
+ */
+#define BRESINITPGON(dy, x1, x2, xStart, d, m, m1, incr1, incr2) { \
+ int dx; /* local storage */ \
+\
+ /* \
+ * if the edge is horizontal, then it is ignored \
+ * and assumed not to be processed. Otherwise, do this stuff. \
+ */ \
+ if ((dy) != 0) { \
+ xStart = (x1); \
+ dx = (x2) - xStart; \
+ if (dx < 0) { \
+ m = dx / (dy); \
+ m1 = m - 1; \
+ incr1 = -2 * dx + 2 * (dy) * m1; \
+ incr2 = -2 * dx + 2 * (dy) * m; \
+ d = 2 * m * (dy) - 2 * dx - 2 * (dy); \
+ } else { \
+ m = dx / (dy); \
+ m1 = m + 1; \
+ incr1 = 2 * dx - 2 * (dy) * m1; \
+ incr2 = 2 * dx - 2 * (dy) * m; \
+ d = -2 * m * (dy) + 2 * dx; \
+ } \
+ } \
+}
+\f
+#define BRESINCRPGON(d, minval, m, m1, incr1, incr2) { \
+ if (m1 > 0) { \
+ if (d > 0) { \
+ minval += m1; \
+ d += incr1; \
+ } \
+ else { \
+ minval += m; \
+ d += incr2; \
+ } \
+ } else {\
+ if (d >= 0) { \
+ minval += m1; \
+ d += incr1; \
+ } \
+ else { \
+ minval += m; \
+ d += incr2; \
+ } \
+ } \
+}
+
+\f
+/*
+ * This structure contains all of the information needed
+ * to run the bresenham algorithm.
+ * The variables may be hardcoded into the declarations
+ * instead of using this structure to make use of
+ * register declarations.
+ */
+typedef struct {
+ int minor; /* minor axis */
+ int d; /* decision variable */
+ int m, m1; /* slope and slope+1 */
+ int incr1, incr2; /* error increments */
+} BRESINFO;
+
+
+#define BRESINITPGONSTRUCT(dmaj, min1, min2, bres) \
+ BRESINITPGON(dmaj, min1, min2, bres.minor, bres.d, \
+ bres.m, bres.m1, bres.incr1, bres.incr2)
+
+#define BRESINCRPGONSTRUCT(bres) \
+ BRESINCRPGON(bres.d, bres.minor, bres.m, bres.m1, bres.incr1, bres.incr2)
+
+
+#endif
projects / rdpsrv / blobdiff