client/player.go

package client

import (
	"math"
	"math/rand"

	"bitbucket.org/hackerbots/server"
	"bitbucket.org/hackerbots/vector"
)

// Player is the interface that is implemented when specifying non-default
// player behavior.
//
// The general case will be to implement a Player type that contains the magic
// required to slay other robots quickly while staying alive for a long time.
type Player interface {
	Update(bs *server.Boardstate) map[string]server.Instruction
}

// SimplePlayer is our default player and stands as a starting point for your
// own Player implementations.
type SimplePlayer struct {
	me             server.Robot
	width, height  float64
	knownObstacles map[string]server.Obstacle
	nearestEnemy   *server.OtherRobot
	fireat         *vector.Point2d
	moveto         *vector.Point2d
	speed          float64
	maxSpeed       float64
	safeDistance   float64
}

// NewSimplePlayer simply returns a populated, usable *SimplePlayer
func NewSimplePlayer(width, height float64) *SimplePlayer {
	return &SimplePlayer{
		knownObstacles: make(map[string]server.Obstacle),
		width:          width,
		height:         height,
		maxSpeed:       100,
		safeDistance:   40,
	}
}

// Update is our implementation of recieving and processing a server.Boardstate
// from the server
func (p *SimplePlayer) Update(bs *server.Boardstate) map[string]server.Instruction {
	instructions := make(map[string]server.Instruction)

	for _, bot := range bs.MyRobots {
		p.me = bot
		p.speed = 1000
		if p.me.Health <= 0 {
			continue
		}

		p.recon(bs)
		p.navigate()

		probe_point := p.me.Position.Add(p.me.Heading.Scale(p.safeDistance))

		instructions[bot.Id] = server.Instruction{
			MoveTo:      p.moveto,
			TargetSpeed: &p.speed,
			FireAt:      p.fireat,
			Probe:       &probe_point,
		}
	}

	return instructions
}

func (p *SimplePlayer) navigate() {
	if p.moveto == nil {
		p.moveto = p.randomDirection()
	}

	togo := p.me.Position.Sub(*p.moveto).Mag()
	if togo < p.safeDistance+5 {
		p.moveto = p.randomDirection()
		return
	}
	if !p.probe(p.me.Position.Add(p.me.Heading.Scale(p.safeDistance))) {
		p.speed = 0
		if !p.probe(*p.moveto) {
			p.moveto = p.randomDirection()
			return
		}
	}
	if p.me.Collision != nil {
		p.moveto = p.randomDirection()
		p.speed = 0
		return
	}
}

func (p *SimplePlayer) recon(bs *server.Boardstate) {
	// XXX: need to keep track of seen objects ..

	// simplest shooting strategy ... need to do the following:
	// not shoot through buildings
	// shoot at where the robot will be, not where it was.
	p.nearestEnemy = nil
	p.fireat = nil
	closest := math.Inf(1)
	for _, enemy := range bs.OtherRobots {
		dist := p.me.Position.Sub(enemy.Position).Mag()
		if dist < closest && dist > p.safeDistance {
			p.nearestEnemy = &enemy
		}
	}
	if p.nearestEnemy != nil {
		point := p.nearestEnemy.Position.Add(p.nearestEnemy.Heading.Scale(p.safeDistance))
		p.fireat = &point
	}
}

// Instruction is our default implementation of preparing a map of information
// to be sent to server.
func (p *SimplePlayer) Instruction() map[string]server.Instruction {
	return map[string]server.Instruction{
		p.me.Id: {
			MoveTo:      p.moveto,
			TargetSpeed: &p.speed,
			FireAt:      p.fireat,
		},
	}
}

func (p *SimplePlayer) randomDirection() *vector.Point2d {
	pt := vector.Vector2d{
		X: rand.Float64() * p.width,
		Y: rand.Float64() * p.height,
	}.ToPoint()
	return &pt
}

func (p *SimplePlayer) probe(destination vector.Point2d) bool {
	// XXX: make test for this
	for _, v := range p.knownObstacles {
		collided, _, _ := vector.RectIntersection(
			v.Bounds,
			p.me.Position,
			destination.Sub(p.me.Position),
		)
		if collided {
			return false
		}
	}
	return true
}