Improved ropes

main.go

@@ -32,20 +32,21 @@ func start() {
 	w4.PALETTE[1] = 0x012824
 	w4.PALETTE[2] = 0x265935
 	w4.PALETTE[3] = 0xff4d6d
-	player = &Player{
-		Position: Vector{80, 80},
-		Speed:    Vector{},
-		Gamepad:  w4.GAMEPAD1,
-	}
 	for i := 0; i < 4; i++ {
 		p, s := CreateRope(
 			Vector{0, rand.Float64()*40 + float64(i*40)},
 			Vector{160, rand.Float64()*40 + float64(i*40)},
-			15,
+			10,
 		)
 		points = append(points, p...)
 		sticks = append(sticks, s...)
 	}
+	player = &Player{
+		Position:     Vector{80, 80},
+		Speed:        Vector{},
+		Gamepad:      w4.GAMEPAD1,
+		StickGrabbed: sticks[rand.Intn(len(sticks)-1)],
+	}
 }
 
 //go:export update

player.go

@@ -1,13 +1,17 @@
 package main
 
-import "cart/w4"
+import (
+	"cart/w4"
+	"math"
+)
 
 type Player struct {
-	Position     Vector
-	Speed        Vector
-	PointGrabbed *Point
+	Position Vector
+	Speed    Vector
+	//PointGrabbed *Point
+	StickGrabbed *Stick
+	StickOffset  float64
 	GrabTimeout  uint
-	Offset       float64
 	Gamepad      *uint8
 }
 
@@ -23,32 +27,74 @@ func (p *Player) Update() {
 		p.Speed.X += 1
 	}
 	isJumping := *p.Gamepad&w4.BUTTON_DOWN == 0
-	p.Speed.Y += gravity
-	if p.PointGrabbed != nil {
+	p.Speed.Y = math.Min(4, p.Speed.Y+gravity)
+	if p.StickGrabbed != nil {
 		p.Speed.Y = 0
-		p.Position = p.PointGrabbed.Position
+		//		p.Position = p.PointGrabbed.Position
+		if *p.Gamepad&w4.BUTTON_LEFT != 0 {
+			p.StickOffset -= 0.1
+		}
+		if *p.Gamepad&w4.BUTTON_RIGHT != 0 {
+			p.StickOffset += 0.1
+		}
+		if p.StickOffset < 0 {
+			point := p.StickGrabbed.PointA
+			if len(point.Sticks) == 1 {
+				p.StickOffset = 0
+			} else {
+				p.StickGrabbed = point.Sticks[0]
+				p.StickOffset += 1
+			}
+		}
+		if p.StickOffset > 1 {
+			point := p.StickGrabbed.PointB
+			if len(point.Sticks) == 1 {
+				p.StickOffset = 1
+			} else {
+				p.StickGrabbed = point.Sticks[1]
+				p.StickOffset -= 1
+			}
+		}
+		p.Position = p.StickGrabbed.GetPosition(p.StickOffset)
 		if *p.Gamepad&w4.BUTTON_2 != 0 {
 			p.GrabTimeout = 10
 			if isJumping {
 				p.GrabTimeout = 5
 				p.Speed.Y = -4.5
+				impulse := p.Speed.MulScalar(-1)
+				p.StickGrabbed.PointA.Position.MoveVec(impulse)
+				p.StickGrabbed.PointB.Position.MoveVec(impulse)
 			}
-			p.PointGrabbed = nil
+			p.StickGrabbed = nil
 		}
 	} else {
 		p.Position.Move(p.Speed.X, p.Speed.Y)
 		if *p.Gamepad&w4.BUTTON_DOWN == 0 && p.GrabTimeout == 0 {
+			distance := math.MaxFloat64
+			var selectedPoint *Point
 			for _, point := range points {
 				diff := p.Position.Sub(point.Position)
-				if diff.LenSquared() < 25 {
-					// nearPoints = append(nearPoints, p)
-					*w4.DRAW_COLORS = 0x44
-					w4.Rect(int(point.Position.X), int(point.Position.Y), 3, 3)
-					p.PointGrabbed = point
-					point.PreviousPosition.Move(-p.Speed.X*2, -p.Speed.Y*2)
-					break
+				dSquared := diff.LenSquared()
+				if dSquared < distance {
+					distance = dSquared
+					selectedPoint = point
 				}
 			}
+			stickDistance := math.MaxFloat64
+			var selectedStick *Stick
+			for _, stick := range selectedPoint.Sticks {
+				distance := stick.GetDistance(p.Position)
+				if distance < stickDistance {
+					stickDistance = distance
+					selectedStick = stick
+				}
+			}
+			if stickDistance < 4 {
+				p.StickGrabbed = selectedStick
+				p.StickOffset = selectedStick.GetOffset(p.Position)
+				p.StickGrabbed.PointA.Position.MoveVec(p.Speed)
+				p.StickGrabbed.PointB.Position.MoveVec(p.Speed)
+			}
 		}
 	}
 }

ropes.go

@@ -3,7 +3,6 @@ package main
 import (
 	"cart/w4"
 	"math"
-	"strconv"
 )
 
 type Point struct {
@@ -11,6 +10,16 @@ type Point struct {
 	PreviousPosition Vector
 	IsLocked         bool
 	TimeOffset       uint64
+	Sticks           []*Stick
+}
+
+func (p *Point) AddStick(stick *Stick) *Point {
+	p.Sticks = append(p.Sticks, stick)
+	return p
+}
+
+func (p *Point) GetMotion() Vector {
+	return p.Position.Sub(p.PreviousPosition)
 }
 
 func (p *Point) Draw() {
@@ -31,6 +40,39 @@ type Stick struct {
 	Length float64
 }
 
+func (s *Stick) GetVector() Vector {
+	return s.PointB.Position.Sub(s.PointA.Position)
+}
+
+func (s *Stick) GetDistance(point Vector) float64 {
+	ab := s.GetVector()
+	ap := point.Sub(s.PointA.Position)
+	bp := point.Sub(s.PointB.Position)
+
+	abbp := (ab.X*bp.X + ab.Y*bp.Y)
+	abap := (ab.X*ap.X + ab.Y*ap.Y)
+
+	if abbp > 0 {
+		return bp.Len()
+	} else if abap < 0 {
+		return ap.Len()
+	}
+	mod := ab.Len()
+	return math.Abs(ab.X*ap.Y-ab.Y*ab.X) / mod
+}
+
+func (s *Stick) GetPosition(offset float64) Vector {
+	diff := s.GetVector()
+	return s.PointA.Position.Sum(diff.MulScalar(offset))
+}
+
+func (s *Stick) GetOffset(p Vector) float64 {
+	ab := s.GetVector()
+	ap := p.Sub(s.PointA.Position)
+	projection := ap.ProjectTo(ab)
+	return projection.Len() / ab.Len()
+}
+
 func (s *Stick) Draw() {
 	*w4.DRAW_COLORS = 0x3
 	w4.Line(int(s.PointA.Position.X), int(s.PointA.Position.Y),
@@ -90,12 +132,13 @@ func CreateRope(start Vector, end Vector, divisions int) ([]*Point, []*Stick) {
 			diffX := pos.X - lastPoint.Position.X
 			diffY := pos.Y - lastPoint.Position.Y
 			len := math.Sqrt(diffX*diffX + diffY*diffY)
-			w4.Trace("Length between points is " + strconv.FormatFloat(len, 'f', 3, 64))
 			stick := Stick{
 				PointA: lastPoint,
 				PointB: &point,
 				Length: len,
 			}
+			stick.PointA.AddStick(&stick)
+			stick.PointB.AddStick(&stick)
 			sticks = append(sticks, &stick)
 		}
 		points = append(points, &point)

vectors.go

@@ -10,6 +10,13 @@ type Vector struct {
 	Y float64
 }
 
+func Vec(x float64, y float64) Vector {
+	return Vector{
+		x,
+		y,
+	}
+}
+
 func (v *Vector) String() string {
 	return "(" + strconv.FormatFloat(v.X, 'f', 3, 64) + "; " + strconv.FormatFloat(v.Y, 'f', 3, 64) + ")"
 }
@@ -57,7 +64,21 @@ func (v *Vector) Normalized() Vector {
 	return Vector{x, y}
 }
 
+func (v *Vector) Dot(v2 Vector) float64 {
+	return v.X*v2.X + v.Y*v2.Y
+}
+
+func (v *Vector) ProjectTo(v2 Vector) Vector {
+	abdot := v.Dot(v2)
+	bbdot := v2.Dot(v2)
+	return v2.MulScalar(abdot / bbdot)
+}
+
 func (v *Vector) Move(x float64, y float64) {
 	v.X += x
 	v.Y += y
 }
+func (v *Vector) MoveVec(v2 Vector) {
+	v.X += v2.X
+	v.Y += v2.Y
+}