added geom and flag in main for deebug cli calls

internal/geom/geom.go

@@ -1,3 +1,20 @@
 package geom
 
-//init
+import "math"
+
+const EPS = 1e-6
+
+type Vec struct {
+	X, Y float64
+}
+
+type Seg struct {
+	A, B Vec
+}
+
+func V(x, y float64) Vec        { return Vec{x, y} }
+func Sub(a, b Vec) Vec          { return Vec{a.X - b.X, a.Y - b.Y} }
+func Dot(a, b Vec) float64      { return a.X*b.X + a.Y*b.Y }
+func Cross(a, b Vec) float64    { return a.X*b.Y - a.Y*b.X }
+func Len(a Vec) float64         { return math.Hypot(a.X, a.Y) }
+func NearlyZero(x float64) bool { return math.Abs(x) < EPS }