Implement basic X/Z control surface

bot/client.go

@@ -24,6 +24,7 @@ type Client struct {
 	settings  Settings
 
 	Wd        world.World //the map data
+	Inputs    phy.Inputs
 	Physics   phy.State
 	lastPosTx time.Time
 

bot/ingame.go

@@ -82,7 +82,7 @@ func (c *Client) HandleGame() error {
 		case <-c.closing:
 			return http.ErrServerClosed
 		case <-cTick.C:
-			if err := c.Physics.Tick(&c.Wd); err != nil {
+			if err := c.Physics.Tick(c.Inputs, &c.Wd); err != nil {
 				c.disconnect()
 				return err
 			}

bot/phy/inputs.go

@@ -0,0 +1,8 @@
+package phy
+
+// Inputs describes the desired movements of the player.
+type Inputs struct {
+	Yaw, Pitch float32
+
+	ThrottleX, ThrottleZ float64
+}

bot/phy/phy.go

@@ -14,7 +14,13 @@ const (
 	playerHeight = 1.8
 	resetVel     = 0.003
 
+	yawSpeed = 3.0
+
 	gravity      = 0.08
+	drag         = 0.98
+	acceleration = 0.02
+	inertia      = 0.91
+	slipperiness = 0.6
 )
 
 // World represents a provider of information about the surrounding world.
@@ -81,10 +87,33 @@ func (s *State) surroundings(query AABB, w World) Surrounds {
 	return out
 }
 
-func (s *State) Tick(w World) error {
+func (s *State) applyInputs(input Inputs, acceleration, inertia float64) {
+	speed := math.Sqrt(input.ThrottleX*input.ThrottleX + input.ThrottleZ*input.ThrottleZ)
+	if speed < 0.01 {
+		return
+	}
+	speed = acceleration / math.Max(speed, 1)
+
+	input.ThrottleX *= speed
+	input.ThrottleZ *= speed
+
+	s.Vel.X += input.ThrottleX
+	s.Vel.Z += input.ThrottleZ
+}
+
+func (s *State) Tick(input Inputs, w World) error {
 	if !s.Run {
 		return nil
 	}
+	var inertia = inertia
+	var acceleration = acceleration
+	if s.onGround {
+		inertia *= slipperiness
+		acceleration = 0.1 * (0.1627714 / (inertia * inertia * inertia))
+	}
+	s.applyInputs(input, acceleration, inertia)
+
+	// Deadzone velocities when they get too low.
 	if math.Abs(s.Vel.X) < resetVel {
 		s.Vel.X = 0
 	}
@@ -94,7 +123,12 @@ func (s *State) Tick(w World) error {
 	if math.Abs(s.Vel.Z) < resetVel {
 		s.Vel.Z = 0
 	}
+	// Gravity
 	s.Vel.Y -= gravity
+	// Drag & friction.
+	s.Vel.Y *= drag
+	s.Vel.X *= inertia
+	s.Vel.Z *= inertia
 
 	// Apply collision.
 	var (

bot/world/world.go

@@ -60,7 +60,7 @@ type ChunkLoc struct {
 func (w *World) GetBlockStatus(x, y, z int) BlockStatus {
 	// Use n>>4 rather then n/16. It acts wrong if n<0.
 	c := w.Chunks[ChunkLoc{x >> 4, z >> 4}]
-	if c != nil {
+	if c != nil && y >= 0 {
 		if sec := c.Sections[y>>4]; sec != nil {
 			return sec.GetBlock(SectionIdx(x&15, y&15, z&15))
 		}