From a3cf74a971c0043bf835d6e3ba94d3b220e9c20f Mon Sep 17 00:00:00 2001
From: surdeus <surdeus@gmail.com>
Date: Sun, 28 May 2023 21:22:52 +0300
Subject: [PATCH] Implemented ContainsPoint function.

---
 src/cmd/math/main.go |  1 +
 src/gx/line.go       | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/cmd/math/main.go b/src/cmd/math/main.go
index 788dd45..d70acc1 100644
--- a/src/cmd/math/main.go
+++ b/src/cmd/math/main.go
@@ -33,6 +33,7 @@ func main() {
 		gx.Point{1, 0},
 	}.Line()
 	fmt.Println(l1.Crosses(l2))
+	fmt.Println(l1.ContainsPoint(gx.Point{1, 4}))
 	/*t := gx.Triangle{
 		gx.Point{0, 0},
 		gx.Point{0, 100},
diff --git a/src/gx/line.go b/src/gx/line.go
index 3fcaf45..e5285a6 100644
--- a/src/gx/line.go
+++ b/src/gx/line.go
@@ -31,12 +31,17 @@ func (l Line) Line() Line {
 	return l
 }
 
-func (l Line) Crosses(with Liner) (Point, bool) {
-	// Parallel liners cannot cross by definition.
-	if l.Parallel(with) {
-		return Point{}, false
+func (l Line) ContainsPoint(p Point) bool {
+	buf := Line{0, p.Y}
+	pc, ok := l.crossesLine(buf)
+	if !ok {
+		return false
 	}
 	
+	return pc == p 
+}
+
+func (l Line) Crosses(with Liner) (Point, bool) {
 	switch with.(type) {
 	case Line :
 		return l.crossesLine(with.(Line))
@@ -48,6 +53,10 @@ func (l Line) Crosses(with Liner) (Point, bool) {
 }
 
 func (l1 Line) crossesLine(l2 Line) (Point, bool) {
+	if l1.Parallel(l2) {
+		return Point{}, false
+	}
+	
 	x := (l1.C - l2.C) / (l2.K - l1.K)
 	y := l1.K*x + l1.C
 	return Point{x, y}, true