diff --git a/src/cmd/math/main.go b/src/cmd/math/main.go
index b029f3a..788dd45 100644
--- a/src/cmd/math/main.go
+++ b/src/cmd/math/main.go
@@ -30,9 +30,9 @@ func main() {
 	
 	l2 := gx.LineSegment{
 		gx.Point{0, 1},
-		gx.Point{1, 2},
+		gx.Point{1, 0},
 	}.Line()
-	fmt.Println(l1.Parallel(l2))
+	fmt.Println(l1.Crosses(l2))
 	/*t := gx.Triangle{
 		gx.Point{0, 0},
 		gx.Point{0, 100},
diff --git a/src/gx/camera.go b/src/gx/camera.go
index a6ac4b4..f8d7088 100644
--- a/src/gx/camera.go
+++ b/src/gx/camera.go
@@ -1,19 +1,11 @@
 package gx
 
-import (
-	"math"
-)
-
 // Implements the camera component
 // for the main window.
 type Camera struct {
 	T Transform
 }
 
-const (
-	Pi = math.Pi
-)
-
 // Returns the matrix satysfying camera
 // position, scale and rotation to apply
 // it to the objects to get the real
diff --git a/src/gx/line.go b/src/gx/line.go
index 3e65f39..3fcaf45 100644
--- a/src/gx/line.go
+++ b/src/gx/line.go
@@ -27,6 +27,32 @@ func (l Line) Parallel(liner Liner) bool {
 	return false
 }
 
+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
+	}
+	
+	switch with.(type) {
+	case Line :
+		return l.crossesLine(with.(Line))
+	case LineSegment :
+		return with.(LineSegment).crossesLine(l)
+	default:
+		panic("unhandled type")
+	}
+}
+
+func (l1 Line) crossesLine(l2 Line) (Point, bool) {
+	x := (l1.C - l2.C) / (l2.K - l1.K)
+	y := l1.K*x + l1.C
+	return Point{x, y}, true
+}
+
 // Get square of length of line segment.
 func (ls LineSegment) LenSqr() Float {
 	return Sqr(ls[0].X - ls[1].X) +
@@ -38,10 +64,6 @@ func (ls LineSegment) Len() Float {
 	return math.Sqrt(ls.LenSqr())
 }
 
-func (l Line) Line() Line {
-	return l
-}
-
 // Returns corresponding to the segment line line.
 func (l LineSegment) Line() Line {
 	p0 := l[0]
@@ -53,8 +75,7 @@ func (l LineSegment) Line() Line {
 	return Line{k, c}
 }
 
-
-func (l LineSegment) Crosses(with any) (bool, Point) {
+func (l LineSegment) Crosses(with Liner) (Point, bool) {
 	switch with.(type) {
 	case Line :
 		return l.crossesLine(with.(Line))
@@ -63,15 +84,26 @@ func (l LineSegment) Crosses(with any) (bool, Point) {
 	default:
 		panic("The type that is not defined to be crossed")
 	}
-	
-	
 }
 
-func (l LineSegment) crossesLineSegment(with LineSegment) (bool, Point) {
-	return false, Point{}
+func (l LineSegment) Contains(what any) bool {
+	switch what.(type) {
+	case Point :
+		return l.containsPoint(what.(Point))
+	default :
+		panic("Unexpected type")
+	}
 }
 
-func (l LineSegment) crossesLine(with Line) (bool, Point) {
-	return false, Point{}
+func (l LineSegment) containsPoint(p Point) bool {
+	return false
+}
+
+func (l LineSegment) crossesLineSegment(with LineSegment) (Point, bool) {
+	return Point{}, false
+}
+
+func (l LineSegment) crossesLine(with Line) (Point, bool) {
+	return Point{}, false 
 }
 
diff --git a/src/gx/main.go b/src/gx/main.go
index 70bc9d6..863b7ea 100644
--- a/src/gx/main.go
+++ b/src/gx/main.go
@@ -7,7 +7,6 @@ import (
 	"github.com/surdeus/godat/src/poolx"
 	//"fmt"
 	"time"
-	"math"
 )
 
 // The type represents order of drawing.
diff --git a/src/gx/math.go b/src/gx/math.go
index c80ea15..97f73fa 100644
--- a/src/gx/math.go
+++ b/src/gx/math.go
@@ -10,6 +10,7 @@ type Float = float64
 
 const (
 	MaxFloat = math.MaxFloat64
+	Pi = math.Pi
 )
 
 // Returns square of the value.
@@ -17,3 +18,11 @@ func Sqr(v Float) Float {
 	return v * v
 }
 
+func RadiansToDegrees(v Float) Float {
+	return v
+}
+
+func DeegresToRadians(v Float) Float {
+	return v
+}
+
diff --git a/src/gx/ray.go b/src/gx/ray.go
index 772d928..6d63c87 100644
--- a/src/gx/ray.go
+++ b/src/gx/ray.go
@@ -1,7 +1,10 @@
 package gx
 
+// The type represents math ray.
 type Ray struct {
+	// The start point.
 	P Point
-	V Vector
+	// Rotation of the ray.
+	R Float
 }