set initial positions

1 files changed, 47 insertions, 0 deletions

diff --git a/geo.c b/geo.c
new file mode 100644
index 0000000..60c0ae2
--- /dev/null
+++ b/geo.c
@@ -0,0 +1,47 @@
+#include <stdlib.h>
+#include <time.h>
+
+#include "balls.h"
+
+static float randFloat(float lo, float hi);
+
+int
+isCollision(float2 p1, float r1, float2 p2, float r2) {
+	float2 dist;
+	float rhs;
+
+	dist = p1 - p2;
+	rhs = r1 + r2;
+	return (dist[0]*dist[0] + dist[1]*dist[1]) <= rhs*rhs;
+}
+
+Rectangle
+insetRect(Rectangle r, float n) {
+	r.min += n;
+	r.max -= n;
+	return r;
+}
+
+float2
+randPtInRect(Rectangle r) {
+	float2 pt = {
+		randFloat(r.min[0], r.max[0]),
+		randFloat(r.min[1], r.max[1])
+	};
+	return pt;
+}
+
+static float
+randFloat(float lo, float hi) {
+	float r, diff;
+	static int isInitialized = 0;
+
+	if (!isInitialized) { /* First call. */
+		srand(time(0));
+		isInitialized = 1;
+	}
+
+	r = (float) rand() / RAND_MAX;
+	diff = hi - lo;
+	return lo + r*diff;
+}