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-rw-r--r--misc.c114
1 files changed, 114 insertions, 0 deletions
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+/*
+ * misc.c - Helper functions for geometry and attributes
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "misc.h"
+
+
+static bool eq(const int m[6], int xx, int xy, int yx, int yy)
+{
+ return m[1] == xx && m[2] == xy && m[4] == yx && m[5] == yy;
+}
+
+
+unsigned matrix_to_angle(const int m[6])
+{
+ if (eq(m, 1, 0, 0, -1))
+ return 0;
+ if (eq(m, 0, -1, -1, 0))
+ return 90;
+ if (eq(m, -1, 0, 0, 1))
+ return 180;
+ if (eq(m, 0, 1, 1, 0))
+ return 270;
+ if (eq(m, -1, 0, 0, -1))
+ return 0;
+ if (eq(m, 1, 0, 0, 1)) /* x-flipped */
+ return 180;
+ if (eq(m, 0, 1, -1, 0)) /* x-flipped, 90 deg */
+ return 90;
+ fprintf(stderr, "unrecognized matrix %d %d %d %d\n",
+ m[1], m[2], m[4], m[5]);
+ exit(1);
+}
+
+
+bool matrix_is_mirrored(const int m[6])
+{
+ if (eq(m, 1, 0, 0, -1))
+ return 0;
+ if (eq(m, 0, -1, -1, 0))
+ return 0;
+ if (eq(m, -1, 0, 0, 1))
+ return 0;
+ if (eq(m, 0, 1, 1, 0))
+ return 0;
+
+ if (eq(m, -1, 0, 0, -1))
+ return 1;
+ if (eq(m, 1, 0, 0, 1))
+ return 1;
+ if (eq(m, 0, 1, -1, 0))
+ return 1;
+ assert(0);
+}
+
+
+int angle_add(int a, int b)
+{
+ a += b;
+ while (a < 0)
+ a += 360;
+ return a % 360;
+}
+
+
+
+int rx(int x, int y, int rot)
+{
+ switch (rot) {
+ case 0:
+ return x;
+ case 90:
+ return y;
+ case 180:
+ return -x;
+ case 270:
+ return -y;
+ default:
+ assert(0);
+
+ }
+}
+
+
+int ry(int x, int y, int rot)
+{
+ switch (rot) {
+ case 0:
+ return y;
+ case 90:
+ return -x;
+ case 180:
+ return -y;
+ case 270:
+ return x;
+ default:
+ assert(0);
+
+ }
+}