183 lines
4.5 KiB
Go
183 lines
4.5 KiB
Go
// Package physics 玩家 AABB 碰撞与逐轴移动（场景/物理与碰撞.md §2）。
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//
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// 核心：分轴解算（X → Z → Y），每轴移动后检测 AABB 与固体方块重叠，重叠则回退该轴。
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// 不用物理引擎：体素世界自己写最快、最可控。
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package physics
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import "math"
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// World 物理层所需的世界接口（与渲染/交互共用同一张 solid 判定表）。
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type World interface {
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Solid(x, y, z int32) bool
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Fluid(x, y, z int32) bool
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}
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const (
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AirMax = 15.0 // 氧气秒数（300 tick）
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standHeight = 1.8
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standEye = 1.62
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sneakHeight = 1.5
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sneakEye = 1.27
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swimHeight = 0.6
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swimEye = 0.4
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)
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// Player 玩家实体（设计.md §7.1：宽 0.6、高 1.8、眼高 1.62）。
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type Player struct {
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Pos [3]float64 // 脚底坐标
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Vel [3]float64 // 速度（方块/秒）
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Width float64
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Height float64
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EyeHeight float64
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OnGround bool
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InWater bool // 脚或躯干在液体
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EyeInWater bool // 眼睛在液体（氧气 / 水下雾）
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Swimming bool
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Flying bool
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Air float64 // 剩余氧气秒数
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FallSpeed float64 // 落地前一帧垂直速度（摔落判定）
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rem [3]float64
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}
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// NewPlayer 创建默认玩家（站立尺寸）。
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func NewPlayer(x, y, z float64) *Player {
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return &Player{
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Pos: [3]float64{x, y, z},
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Width: 0.6,
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Height: standHeight,
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EyeHeight: standEye,
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Air: AirMax,
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}
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}
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// Move 逐轴移动（物理与碰撞.md §2.2）：X → Z → Y，每轴独立碰撞回退。
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func (p *Player) Move(w World, dx, dy, dz float64) {
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p.OnGround = false
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deltas := [3]float64{dx, dy, dz}
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for _, axis := range [3]int{0, 2, 1} {
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p.Pos[axis] += deltas[axis]
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if p.Collides(w) {
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p.Pos[axis] -= deltas[axis]
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p.Vel[axis] = 0
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if axis == 1 && deltas[axis] < 0 {
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p.OnGround = true
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}
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}
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}
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p.updateFluid(w)
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}
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func (p *Player) updateFluid(w World) {
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fx := int32(math.Floor(p.Pos[0]))
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fz := int32(math.Floor(p.Pos[2]))
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foot := w.Fluid(fx, int32(math.Floor(p.Pos[1]+0.3)), fz)
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mid := w.Fluid(fx, int32(math.Floor(p.Pos[1]+p.Height*0.6)), fz)
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p.InWater = foot || mid
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eye := p.Eye()
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p.EyeInWater = w.Fluid(int32(math.Floor(eye[0])), int32(math.Floor(eye[1])), int32(math.Floor(eye[2])))
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}
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// Collides 当前位置 AABB 是否与固体方块重叠（含边界 epsilon 防抖动）。
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func (p *Player) Collides(w World) bool {
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const eps = 1e-6
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minX := int32(math.Floor(p.Pos[0] - p.Width/2 + eps))
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maxX := int32(math.Floor(p.Pos[0] + p.Width/2 - eps))
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minY := int32(math.Floor(p.Pos[1] + eps))
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maxY := int32(math.Floor(p.Pos[1] + p.Height - eps))
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minZ := int32(math.Floor(p.Pos[2] - p.Width/2 + eps))
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maxZ := int32(math.Floor(p.Pos[2] + p.Width/2 - eps))
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for x := minX; x <= maxX; x++ {
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for y := minY; y <= maxY; y++ {
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for z := minZ; z <= maxZ; z++ {
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if w.Solid(x, y, z) {
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return true
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}
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}
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}
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}
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return false
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}
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// Eye 返回眼睛位置（相机位置）。
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func (p *Player) Eye() [3]float64 {
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return [3]float64{p.Pos[0], p.Pos[1] + p.EyeHeight, p.Pos[2]}
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}
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// SetPose 切换潜行/游泳碰撞箱；站立会卡住则保持当前矮箱。
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func (p *Player) SetPose(w World, sneak, swim bool) {
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oldH, oldE := p.Height, p.EyeHeight
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switch {
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case swim && p.InWater:
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p.Height, p.EyeHeight, p.Swimming = swimHeight, swimEye, true
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case sneak:
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p.Height, p.EyeHeight, p.Swimming = sneakHeight, sneakEye, false
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default:
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p.Height, p.EyeHeight, p.Swimming = standHeight, standEye, false
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}
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if p.Collides(w) {
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p.Height, p.EyeHeight = oldH, oldE
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if oldH <= swimHeight+0.01 {
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p.Swimming = true
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}
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}
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}
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// TickAir 氧气：眼睛在水递减，出水回满（物理与碰撞.md §4）。
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func (p *Player) TickAir(dt float64) {
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if p.EyeInWater {
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p.Air -= dt
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if p.Air < 0 {
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p.Air = 0
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}
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} else {
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p.Air = AirMax
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}
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}
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// Tick 重力与液体阻力积分（dt 秒）。
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func (p *Player) Tick(w World, dt float64) {
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const gravity = 32.0
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p.FallSpeed = p.Vel[1]
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if !p.Flying {
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if p.InWater {
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p.Vel[1] -= gravity * 0.15 * dt
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p.Vel[1] *= 1 - 3.0*dt
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if p.Vel[1] < -4 {
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p.Vel[1] = -4
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}
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} else {
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p.Vel[1] -= gravity * dt
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if p.Vel[1] < -64 {
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p.Vel[1] = -64
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}
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}
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}
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p.Move(w, p.Vel[0]*dt, p.Vel[1]*dt, p.Vel[2]*dt)
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p.TickAir(dt)
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}
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// Jump 起跳（仅落地时生效；约 1.25 方块高度）。
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func (p *Player) Jump() {
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if p.OnGround {
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p.Vel[1] = 9.0
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p.OnGround = false
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}
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}
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// SwimUp 水中上浮（不要求落地）。
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func (p *Player) SwimUp() {
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if p.InWater {
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p.Vel[1] = 4.2
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}
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}
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// SwimDown 水中下潜。
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func (p *Player) SwimDown() {
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if p.InWater {
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p.Vel[1] = -3.2
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}
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}
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