diff --git a/cmd/test/trianlge.go b/cmd/test/trianlge.go
index 053b04c..f6f57f6 100644
--- a/cmd/test/trianlge.go
+++ b/cmd/test/trianlge.go
@@ -33,7 +33,7 @@ func NewTri() *Tri {
 
 func (t *Tri) Update(c *Context) {
 	dt := c.Dt().Seconds()
-	if t.ContainsPoint(c.AbsCursorPosition()) {
+	if !t.ContainedPoints(gg.Points{c.AbsCursorPosition()}).Empty() {
 		t.Color = gg.Rgba(0, 1, 0, 1)
 	} else {
 		t.Color = gg.Rgba(1, 0, 1, 1)
diff --git a/collider.go b/collider.go
index d2f33b2..2f16c79 100644
--- a/collider.go
+++ b/collider.go
@@ -6,19 +6,25 @@ package gg
 // if the the bigger collider that
 // contains more complicated (accurate) structure
 // do collide.
-type ColliderSimplifier interface {
-	ColliderSimplify() Triangle
-}
+//type ColliderSimplifier interface {
+	//ColliderSimplify() Triangle
+//}
 
-// The structure represents all
-// information on collisions.
+type CollisionType int
+const (
+	CollisionTypePhys CollisionType = iota
+	CollisionTypeTrigger
+)
+
+// The structure contains collision information.
 type Collision struct {
-	Current, With any
+	Type CollisionType
+	What, With Objecter
+	// Points of Self contained in 
+	Points Points
+	Crosses []LineCross
 }
 
-type PointContainer interface {
-	ContainsPoint(Point) bool
-}
 
 // Implementing the interface lets the engine
 // to determine if the object collides with anything.
@@ -26,8 +32,60 @@ type PointContainer interface {
 // inner structure field as first argument.
 // The Collide method will be called on collisions.
 type Collider interface {
-	Collides(Collider) *Collision
-	Collide(*Collision)
+	// Checks whether the object is collidable
+	IsCollidable() bool
+	Verticer
+	Edger
+	PointContainer
+}
+type Collidability struct {
+	Collidable bool
+}
+func (c Collidability) IsCollidable() bool {
+	return c.Collidable
+}
+type PointContainer interface {
+	ContainedPoints(Points) Points
+}
+type Verticer interface {
+	Vertices() Vertices
+}
+type Edger interface {
+	Edges() Edges
 }
 
+// Implementing the type provides way
+// to resolve collisions and other problems.
+// The Resolve() is called right after the Update() of Updater.
+type Resolver interface {
+	IsResolvable() bool
+	Resolve(c *Context)
+	Collider
+}
+type Resolvability struct {
+	Resolvable bool
+}
+func (r Resolvability) IsResolvable() bool {
+	return r.Resolvable
+}
 
+func Collide(c1, c2 Collider) (Collision, bool) {
+	vertices := c1.Vertices()
+	es1, es2 := c1.Edges(), c2.Edges()
+	crosses, doCross := es1.LineCrossWith(es2)
+	pts := c2.ContainedPoints(vertices)
+	return Collision{
+		Points: pts,
+		Crosses: crosses,
+	}, len(pts) != 0 || doCross
+}
+
+func GetCollisions(c Collider, cs []Collider) []Collision {
+	ret := []Collision{}
+	for _, ic := range cs {
+		if !ic.IsCollidable() || ic == c {
+			continue
+		}
+	}
+	return ret
+}
diff --git a/context.go b/context.go
index 0b4a3fc..63f9c6e 100644
--- a/context.go
+++ b/context.go
@@ -4,6 +4,7 @@ type contextType int
 const (
 	startContext contextType = iota
 	updateContext
+	resolveContext
 	eventContext
 	drawContext
 	deleteContext
@@ -12,6 +13,7 @@ const (
 type Context struct {
 	typ contextType
 	Events []any
+	Collisions []Collision
 	*Engine
 	*Image
 }
diff --git a/edge.go b/edge.go
new file mode 100644
index 0000000..fcc58ee
--- /dev/null
+++ b/edge.go
@@ -0,0 +1,78 @@
+package gg
+
+type Edges []Edge
+// Get crosses of edges.
+func (what Edges) LineCrossWith(with Edges) ([]LineCross, bool) {
+	ret := []LineCross{}
+	for i := range what {
+		for j := range with {
+			cross, doCross := LinersCross(what[i], with[j])
+			if doCross {
+				ret = append(ret, cross)
+			}
+		}
+	}
+	
+	if len(ret) == 0 {
+		return nil, false
+	}
+
+	return ret, true
+}
+
+// The type represents a line segment. The name is for short.
+type Edge [2]Vector
+
+// Returns corresponding to the segment Line.
+func (l Edge) Line() Line {
+	p0 := l[0]
+	p1 := l[1]
+	
+	k := (p0.Y - p1.Y) / (p0.X - p1.X)
+	c := p0.Y - p0.X*k 
+	
+	return Line{k, c}
+}
+
+func (l Edge) ContainedPoints(pts Points) (Points) {
+	ret := Points{}
+	for i := range pts {
+		if l.ContainsPoint(pts[i]) {
+			ret = append(ret, pts[i])
+		}
+	}
+	return ret
+}
+
+// Check if the edge contains the specified point.
+func (l Edge) ContainsPoint(p Point) bool {
+	line := l.Line()
+	if !line.ContainsPoint(p) {
+		return false
+	}
+	
+	xMax := Max(l[0].X, l[1].X)	
+	xMin := Min(l[0].X, l[1].X)	
+	
+	yMax := Max(l[0].Y, l[1].Y)	
+	yMin := Min(l[0].Y, l[1].Y)	
+	
+	if !(xMin < p.X && p.X < xMax) ||
+		!(yMin < p.Y && p.Y < yMax) {
+			return false
+	}
+	
+	return true
+}
+
+// Get square of length of line segment (for performance sometimes).
+func (ls Edge) LenSqr() Float {
+	return Sqr(ls[0].X - ls[1].X) +
+		Sqr(ls[0].Y - ls[1].Y)
+}
+
+// Get length of the line segment.
+func (ls Edge) Len() Float {
+	return Sqrt(ls.LenSqr())
+}
+
diff --git a/engine.go b/engine.go
index 7b82329..6a97039 100644
--- a/engine.go
+++ b/engine.go
@@ -232,14 +232,9 @@ func (e *Engine) Runes() []rune {
 	return e.runes
 }
 
-func (e *engine) Update() error {
+func (e *engine) UpdateEvents() []any {
+
 	eng := (*Engine)(e)
-	e.dt = time.Since(e.lastTime)
-
-	e.runes = ebiten.AppendInputChars(e.runes[:0])
-	fmt.Println("runes:", e.runes)
-	// Buffering the context for faster.
-
 	e.prevKeys = e.keys
 	e.keys = inpututil.
 		AppendPressedKeys(e.keys[:0])
@@ -261,10 +256,10 @@ func (e *engine) Update() error {
 	}
 
 	x, y := ebiten.Wheel()
-	eng.wheel = V(x, y)
-	if !(eng.wheel.Eq(ZV)) {
+	e.wheel = V(x, y)
+	if !(e.wheel.Eq(ZV)) {
 		events = append(events, &WheelChange{
-			Offset: eng.wheel,
+			Offset: e.wheel,
 		})
 	}
 
@@ -284,22 +279,34 @@ func (e *engine) Update() error {
 	}
 
 	realPos := eng.cursorPosition()
-	if !realPos.Eq(eng.cursorPos) {
+	if !realPos.Eq(e.cursorPos) {
 		absM := eng.Camera.AbsMatrix()
 
-		absPrevPos :=eng.cursorPos.Apply(absM)
+		absPrevPos := e.cursorPos.Apply(absM)
 		absPos := realPos.Apply(absM)
 
 		events = append(events, &MouseMove{
-			Real: realPos.Sub(eng.cursorPos),
+			Real: realPos.Sub(e.cursorPos),
 			Abs: absPos.Sub(absPrevPos),
 		})
-		eng.cursorPos = realPos
+		e.cursorPos = realPos
 	}
+	return events
+}
 
+func (e *engine) Update() error {
+
+	eng := (*Engine)(e)
+	e.dt = time.Since(e.lastTime)
+
+	e.runes = ebiten.AppendInputChars(e.runes[:0])
+	fmt.Println("runes:", e.runes)
+	// Buffering the context for faster.
 	// Providing the events to the objects.
 	// Maybe should think of the better way,
 	// but for it is simple enough.
+
+	events := e.UpdateEvents()
 	c := &Context{
 		Engine: eng,
 		typ: updateContext,
@@ -310,11 +317,26 @@ func (e *engine) Update() error {
 		object.Input() <- c
 	}
 	e.wg.Wait()
+	e.Resolve()
+
 	e.lastTime = time.Now()
 	e.frame++
 	return nil
 }
 
+func (e *engine) Resolve() {
+	colliders := []Collider{}
+	resolvers := []Resolver{}
+	for _, object := range e.Objects.store {
+		if object.IsCollidable() {
+			colliders = append(colliders, object)
+		}
+		if object.IsResolvable() {
+			resolvers = append(resolvers, object)
+		}
+	}
+}
+
 var (
 	fullPageIndexes = func() [MaxVertices]uint16 {
 		ret := [MaxVertices]uint16{}
diff --git a/line.go b/line.go
index 5068fc2..e89664b 100644
--- a/line.go
+++ b/line.go
@@ -1,88 +1,15 @@
 package gg
 
-import (
-	"math"
-	//"fmt"
-)
-
 // The type represents mathematical equation of line and line itself.
 type Line struct {
 	K, C Float
 }
 
-type Liner interface {
-	Line() Line
-}
-
-type LinerPointContainer interface {
-	Liner
-	PointContainer
-}
-
-// The type represents a line segment.
-type LineSegment [2]Point
-
-// The type represents multiple line segments.
-type LineSegments []LineSegment
-
-type Edge = LineSegment
-type Edges = LineSegments
-
-
-
-// Check if two LinerPointContainers do cross and return the
-// crossing point.
-func LinersCross(lp1, lp2 LinerPointContainer) (Point, bool) {
-	l1 := lp1.Line()
-	l2 := lp2.Line()
-	
-	p, crosses := l1.crossesLine(l2)
-	if !crosses ||
-			!lp1.ContainsPoint(p) ||
-			!lp2.ContainsPoint(p) {
-		return Point{}, false
-	}
-	
-	return p, true
-}
-
-// Check whether the liner is parallel to the other liner.
-func LinersParallel(first, second Liner) bool {
-	l1 := first.Line()
-	l2 := second.Line()
-	
-	return l1.K == l2.K
-}
-
-// Returns angle between liners in radians.
-// The value fits the -Pi < Value < Pi condition.
-func LinersAngle(first, second Liner) Float {
-	l1 := first.Line()
-	l2 := second.Line()
-	
-	if l1.K == l2.K {
-		return 0
-	}
-	
-	return math.Atan(l1.K/l2.K)
-}
-
 // Returns the line itself. Made to implement the Liner interface.
 func (l Line) Line() Line {
 	return l
 }
 
-// Returns corresponding to the segment line line.
-func (l LineSegment) Line() Line {
-	p0 := l[0]
-	p1 := l[1]
-	
-	k := (p0.Y - p1.Y) / (p0.X - p1.X)
-	c := p0.Y - p0.X*k 
-	
-	return Line{k, c}
-}
-
 func (l Line) ContainsPoint(p Point) bool {
 	buf := Line{0, p.Y}
 	pc, ok := l.crossesLine(buf)
@@ -93,26 +20,6 @@ func (l Line) ContainsPoint(p Point) bool {
 	return pc == p 
 }
 
-func (l LineSegment) ContainsPoint(p Point) bool {
-	line := l.Line()
-	if !line.ContainsPoint(p) {
-		return false
-	}
-	
-	xMax := Max(l[0].X, l[1].X)	
-	xMin := Min(l[0].X, l[1].X)	
-	
-	yMax := Max(l[0].Y, l[1].Y)	
-	yMin := Min(l[0].Y, l[1].Y)	
-	
-	if !(xMin < p.X && p.X < xMax) ||
-		!(yMin < p.Y && p.Y < yMax) {
-			return false
-	}
-	
-	return true
-}
-
 func (l1 Line) crossesLine(l2 Line) (Point, bool) {
 	if LinersParallel(l1, l2) {
 		return Point{}, false
@@ -124,30 +31,3 @@ func (l1 Line) crossesLine(l2 Line) (Point, bool) {
 }
 
 
-// Get square of length of line segment.
-func (ls LineSegment) LenSqr() Float {
-	return Sqr(ls[0].X - ls[1].X) +
-		Sqr(ls[0].Y - ls[1].Y)
-}
-
-// Get length of the line segment.
-func (ls LineSegment) Len() Float {
-	return math.Sqrt(ls.LenSqr())
-}
-
-func (what LineSegments) Cross(with LineSegments) ([][2]int, Points) {
-	indexes := [][2]int{}
-	points := Points{}
-	for i := range what {
-		for j := range with {
-			p, cross := LinersCross(what[i], with[j])
-			if cross {
-				points = append(points, p)
-				indexes = append(indexes, [2]int{i, j})
-			}
-		}
-	}
-	
-	return indexes, points
-}
-
diff --git a/liner.go b/liner.go
new file mode 100644
index 0000000..965511e
--- /dev/null
+++ b/liner.go
@@ -0,0 +1,56 @@
+package gg
+
+type Liner interface {
+	Line() Line
+}
+
+type LinerPointContainer interface {
+	Liner
+	PointContainer
+}
+
+// The type represents the cross of 2 Liners.
+type LineCross struct {
+	Pair [2]Line
+	Point Point
+}
+
+// Check if two LinerPointContainers do cross and return the
+// crossing point.
+func LinersCross(lp1, lp2 LinerPointContainer) (LineCross, bool) {
+	l1 := lp1.Line()
+	l2 := lp2.Line()
+	
+	crossPt, doCross := l1.crossesLine(l2)
+	if !doCross ||
+			len(lp1.ContainedPoints([]Point{crossPt}))==0 ||
+			len(lp2.ContainedPoints([]Point{crossPt}))==0 {
+		return LineCross{}, false
+	}
+	
+	return LineCross{
+		Pair: [2]Line{l1, l2},
+		Point: crossPt,
+	}, true
+}
+
+// Check whether the liner is parallel to the other liner.
+func LinersParallel(first, second Liner) bool {
+	l1 := first.Line()
+	l2 := second.Line()
+	
+	return l1.K == l2.K
+}
+
+// Returns angle between liners in radians.
+// The value fits the -Pi < Value < Pi condition.
+func LinersAngle(first, second Liner) Float {
+	l1 := first.Line()
+	l2 := second.Line()
+	
+	if l1.K == l2.K {
+		return 0
+	}
+	
+	return Atan(l1.K/l2.K)
+}
diff --git a/math.go b/math.go
index 6b18728..98a67bf 100644
--- a/math.go
+++ b/math.go
@@ -24,6 +24,10 @@ func Sqr(v Float) Float {
 	return v * v
 }
 
+func Sqrt(v Float) Float {
+	return math.Sqrt(v)
+}
+
 func Asin(v Float) Float {
 	return math.Asin(v)
 }
diff --git a/object.go b/object.go
index 1c54efc..8f0082e 100644
--- a/object.go
+++ b/object.go
@@ -54,14 +54,19 @@ type Objecter interface {
 	Input() chan *Context
 	Starter
 	Updater
+	Collider
+	Resolver
 	Drawer
 	Deleter
 }
 
 // The type for embedding into engine-in types.
 type Object struct {
+	Collidability
+	Resolvability
 	Layer
 	Visibility
+
 	input chan *Context
 }
 
@@ -69,7 +74,15 @@ func (o *Object) GetObject() *Object { return o }
 func (o *Object) Input() chan *Context { return o.input }
 
 func (o *Object) Start(c *Context) {}
+
 func (o *Object) Update(c *Context) {}
+
+func (o *Object) ContainedPoints(Points) Points {return Points{}}
+func (o *Object) Vertices() Vertices {return Vertices{}}
+func (o *Object) Edges() Edges {return Edges{}}
+
+func (o *Object) Resolve(c *Context) {}
+
 func (o *Object) Draw(c *Context) []EVertex { return nil}
 func (o *Object) Delete(c *Context) {}
 
diff --git a/point.go b/point.go
new file mode 100644
index 0000000..b8080d4
--- /dev/null
+++ b/point.go
@@ -0,0 +1,8 @@
+package gg
+
+type Point = Vector
+type Points []Point
+
+func (pts Points) Empty() bool {
+	return len(pts) == 0
+}
diff --git a/polygon.go b/polygon.go
index bf4b15f..0f31c4a 100644
--- a/polygon.go
+++ b/polygon.go
@@ -10,17 +10,8 @@ type Polygon struct {
 	Triangles
 }
 
-func (p Polygon) ContainsPoint(pnt Point) bool {
-	return p.MakeTriangles().ContainsPoint(pnt)
-}
-
-// Polygon that can be drawn.
-type DrawablePolygon struct {
-	Polygon
-	
-	ShaderOptions
-	Visibility
-	Colority
+func (p Polygon) ContainedPoints(pts Points) (Points) {
+	return p.MakeTriangles().ContainedPoints(pts)
 }
 
 func (p Polygon) MakeTriangles() Triangles {
@@ -37,6 +28,14 @@ func (p Polygon) MakeTriangles() Triangles {
 	return ret
 }
 
+// Polygon that can be drawn.
+type DrawablePolygon struct {
+	Polygon
+	ShaderOptions
+	Visibility
+	Colority
+}
+
 func (p *DrawablePolygon) Draw(c *Context) []EVertex {
 	return (&DrawableTriangles{
 		Colority: p.Colority,
diff --git a/rect.go b/rect.go
index ba644a4..4b70ea2 100644
--- a/rect.go
+++ b/rect.go
@@ -7,28 +7,16 @@ import (
 	//"image"
 )
 
-// The type describes rectangle geometry.
+// The type describes rectangle geometry with
+// way to move, rotate and scale it.
 type Rectangle struct {
 	Object
 	Transform
-}
-
-// The type describes rectangle that can be drawn.
-type DrawableRectangle struct {
-	Rectangle
-	ShaderOptions
-	
-	// Solid color of the rectangle.
-	// Will be ignored if the Shader
-	// field is not nil.
-	Colority
-	
-	// Should be draw or not.
-	Visibility
+	Width, Height Float
 }
 
 // Return points of vertices of the rectangle.
-func (r Rectangle) Vertices() Points {
+func (r Rectangle) Vertices() Vertices {
 	m := r.Matrix()
 	p1 := V(0, 0).Apply(m)
 	p2 := V(1, 0).Apply(m)
@@ -39,11 +27,11 @@ func (r Rectangle) Vertices() Points {
 
 func (r Rectangle) Edges() Edges {
 	vs := r.Vertices()
-	return LineSegments{
-		LineSegment{vs[0], vs[1]},
-		LineSegment{vs[1], vs[2]},
-		LineSegment{vs[2], vs[3]},
-		LineSegment{vs[3], vs[0]},
+	return Edges{
+		Edge{vs[0], vs[1]},
+		Edge{vs[1], vs[2]},
+		Edge{vs[2], vs[3]},
+		Edge{vs[3], vs[0]},
 	}
 }
 
@@ -62,8 +50,23 @@ func (r Rectangle) MakeTriangles() Triangles {
 }
 
 // Check whether the rectangle contains the point.
-func (r Rectangle) ContainsPoint(p Point) bool {
-	return r.MakeTriangles().ContainsPoint(p)
+func (r Rectangle) ContainedPoints(pts Points) (Points) {
+	return r.MakeTriangles().ContainedPoints(pts)
+}
+
+// The type describes rectangle that can be drawn.
+type DrawableRectangle struct {
+	Rectangle
+	ShaderOptions
+	
+	// Solid color of the rectangle.
+	// Will be ignored if the Shader
+	// field is not nil.
+	Colority
+	
+	// Should be draw or not.
+	Visibility
+	Collidability
 }
 
 // Check whether the drawable rectangle should be drawn.
diff --git a/size.go b/size.go
new file mode 100644
index 0000000..02877ab
--- /dev/null
+++ b/size.go
@@ -0,0 +1,12 @@
+package gg
+
+// The type describes a simple
+// rectangle without transformations.
+type Size struct {
+	// The upper left corner position point.
+	Position Point
+	// Absolute width and height.
+	Width, Height Float
+}
+
+//type (s Size) ContainsPoint
diff --git a/sprite.go b/sprite.go
index 26733f9..d0d8970 100644
--- a/sprite.go
+++ b/sprite.go
@@ -11,6 +11,8 @@ type Sprite struct {
 	ShaderOptions
 	Floating bool
 	Visibility
+	Collidability
+	Resolvability
 }
 
 var (
diff --git a/triangle.go b/triangle.go
index 72d8daf..4106f66 100644
--- a/triangle.go
+++ b/triangle.go
@@ -15,7 +15,6 @@ type Vertex struct {
 }
 
 type Triangle [3]Vector
-type Triangles []Triangle
 type DrawableTriangles struct {
 	Triangles
 	Colority
@@ -53,9 +52,9 @@ func sqr(v Float) Float {
 // Return squares of lengths of sides of the triangle.
 func (t Triangle) SideLengthSquares() ([3]Float) {
 	
-	l1 := LineSegment{t[0], t[1]}.LenSqr()
-	l2 := LineSegment{t[1], t[2]}.LenSqr()
-	l3 := LineSegment{t[2], t[0]}.LenSqr()
+	l1 := Edge{t[0], t[1]}.LenSqr()
+	l2 := Edge{t[1], t[2]}.LenSqr()
+	l3 := Edge{t[2], t[0]}.LenSqr()
 	
 	return [3]Float{l1, l2, l3}
 }
@@ -72,19 +71,36 @@ func (t Triangle) ContainsPoint(p Point) bool {
 	return !(neg && pos)
 }
 
+func (t Triangle) ContainedPoints(pts Points) []Point {
+	ret := []Point{}
+	for i := range pts {
+		if t.ContainsPoint(pts[i]) {
+			ret = append(ret, pts[i])
+		}
+	}
+	return ret
+}
+
 func (t Triangle) Sgn() Float {
 	return (t[0].X - t[2].X) * (t[1].Y - t[2].Y)  -
 		(t[1].X - t[2].X) * (t[0].Y - t[2].Y)
 }
 
-func (ts Triangles) ContainsPoint(p Point) bool {
+func (t Triangle) Vertices() Vertices {
+	return Vertices{
+		t[0], t[1], t[2],
+	}
+}
+type Triangles []Triangle
+
+func (ts Triangles) ContainedPoints(pts Points) (Points) {
+	ret := []Point{}
 	for _, t := range ts {
-		if t.ContainsPoint(p) {
-			return true
-		}
+		ps := t.ContainedPoints(pts)
+		ret = append(ret, ps...)
 	}
 	
-	return false
+	return ret
 }
 
 func (r *DrawableTriangles) MakeEVertices(c *Context) []EVertex {
diff --git a/vector.go b/vector.go
index 3babf6c..8d3175c 100644
--- a/vector.go
+++ b/vector.go
@@ -15,11 +15,7 @@ type Vector struct {
 func (v Vector) XY() (Float, Float) {
 	return v.X, v.Y
 }
-type Point = Vector
-//type Vertex = Vector
-
 type Vectors []Vector
-type Points []Point
 
 func V(x, y Float) Vector {
 	return Vector{x, y}
@@ -94,11 +90,11 @@ func (v Vector) Norm() Vector {
 	return V(v.X / l, v.Y / l)
 }
 
-func (pts Points) Contained(c PointContainer) Points {
+func (pts Points) ContainedIn(c PointContainer) Points {
 	ret := make([]Point, 0, len(pts))
 	
 	for _, pt := range pts {
-		if c.ContainsPoint(pt) {
+		if !c.ContainedPoints(Points{pt}).Empty() {
 			ret = append(ret, pt)
 		}
 	}
diff --git a/vertice.go b/vertice.go
new file mode 100644
index 0000000..c6d4cb1
--- /dev/null
+++ b/vertice.go
@@ -0,0 +1,5 @@
+package gg
+
+type Vertice = Point
+type Vertices = []Vertice
+