crude player physics & collision response

Sources/Voxelotl/AABB.swift

@@ -0,0 +1,58 @@
+import simd
+
+struct AABB {
+  private var _bounds: simd_float2x3
+
+  var lower: SIMD3<Float> {
+    get { _bounds[0] }
+    set(row) { self._bounds[0] = row }
+  }
+  var upper: SIMD3<Float> {
+    get { _bounds[1] }
+    set(row) { self._bounds[1] = row }
+  }
+  var center: SIMD3<Float> {
+    get { (self._bounds[0] + self._bounds[1]) / 2 }
+  }
+  var size: SIMD3<Float> {
+    get { self._bounds[1] - self._bounds[0] }
+  }
+
+  var left: Float   { self._bounds[0].x }
+  var bottom: Float { self._bounds[0].y }
+  var far: Float    { self._bounds[0].z }
+  var right: Float  { self._bounds[1].x }
+  var top: Float    { self._bounds[1].y }
+  var near: Float   { self._bounds[1].z }
+
+  private init(bounds: simd_float2x3) {
+    self._bounds = bounds
+  }
+
+  init(from: SIMD3<Float>, to: SIMD3<Float>) {
+    self.init(bounds: .init(from, to))
+  }
+
+  static func fromUnitCube(position: SIMD3<Float> = .zero, scale: SIMD3<Float> = .one) -> Self {
+    self.init(
+      from: position - scale,
+      to:   position + scale)
+  }
+
+  func touching(_ other: Self) -> Bool{
+    let distLower = other._bounds[0] - self._bounds[1]  // x: left, y: bottom, z: far
+    let distUpper = self._bounds[0] - other._bounds[1]  // x: right, y: top, z: near
+
+    if distLower.x > 0 || distUpper.x > 0 { return false }
+    if distLower.y > 0 || distUpper.y > 0 { return false }
+    if distLower.z > 0 || distUpper.z > 0 { return false }
+
+    return true
+  }
+}
+
+extension AABB {
+  static func + (lhs: Self, rhs: SIMD3<Float>) -> Self {
+    .init(bounds: lhs._bounds + .init(rhs, rhs))
+  }
+}

Sources/Voxelotl/CMakeLists.txt

@@ -9,6 +9,7 @@ add_executable(Voxelotl MACOSX_BUNDLE
   FloatExtensions.swift
   Matrix4x4.swift
   Rectangle.swift
+  AABB.swift
 
   NSImageLoader.swift
   Renderer.swift

Sources/Voxelotl/Game.swift

@@ -1,16 +1,39 @@
 import simd
 
-struct Instance {
-  var position: SIMD3<Float> = .zero
-  var scale: SIMD3<Float>    = .one
-  var rotation: simd_quatf   = .identity
-  var color: SIMD4<Float>    = .one
+struct Box {
+  var geometry: AABB
+  var color: SIMD4<Float> = .one
 }
 
+struct Instance {
+  let position: SIMD3<Float>
+  let scale: SIMD3<Float>
+  let rotation: simd_quatf
+  let color: SIMD4<Float>
+
+  init(
+    position: SIMD3<Float> = .zero,
+    scale: SIMD3<Float> = .one,
+    rotation: simd_quatf = .identity,
+    color: SIMD4<Float> = .one
+  ) {
+    self.position = position
+    self.scale = scale
+    self.rotation = rotation
+    self.color = color
+  }
+}
+
+let boxes: [Box] = [
+  Box(geometry: .fromUnitCube(position: .init(0, -1, 0) * 2, scale: .init(10, 0.1, 10) * 2)),
+  Box(geometry: .fromUnitCube(position: .init(-2.5, 0, -3) * 2, scale: .init(repeating: 2)), color: .init(1, 0.5, 0.75, 1)),
+  Box(geometry: .fromUnitCube(position: .init(-2.5, -0.5, -5) * 2, scale: .init(repeating: 2)), color: .init(0.75, 1, 1, 1))
+]
+
 class Game: GameDelegate {
 
   private var fpsCalculator = FPSCalculator()
-  var camera = Camera(fov: 60, size: .one, range: 0.03...25)
+  var camera = Camera(fov: 60, size: .one, range: 0.06...50)
   var player = Player()
   var projection: matrix_float4x4 = .identity
 
@@ -24,7 +47,7 @@ class Game: GameDelegate {
       print("FPS: \(fps)")
     }
 
-    player.update(deltaTime: deltaTime)
+    player.update(deltaTime: deltaTime, boxes: boxes)
     camera.position = player.position
     camera.rotation =
       simd_quatf(angle: player.rotation.y, axis: .init(1, 0, 0)) *
@@ -34,16 +57,18 @@ class Game: GameDelegate {
   func draw(_ renderer: Renderer, _ time: GameTime) {
     let totalTime = Float(time.total.asFloat)
 
-    let instances: [Instance] = [
+    var instances: [Instance] = boxes.map {
       Instance(
-        position: .init(0, sin(totalTime * 1.5) * 0.5, -2),
-        scale: .init(repeating: 0.25),
+        position: $0.geometry.center,
+        scale: $0.geometry.size * 0.5,
+        color: $0.color)
+    }
+    instances.append(
+      Instance(
+        position: .init(0, sin(totalTime * 1.5) * 0.5, -2) * 2,
+        scale: .init(repeating: 0.5),
         rotation: .init(angle: totalTime * 3.0, axis: .init(0, 1, 0)),
-        color: .init(0.5, 0.5, 1, 1)),
-      Instance(position: .init(0, -1, 0), scale: .init(10, 0.1, 10)),
-      Instance(position: .init(-2.5, 0, -3), color: .init(1, 0.5, 0.75, 1)),
-      Instance(position: .init(-2.5, -0.5, -5), color: .init(0.75, 1, 1, 1))
-    ]
+        color: .init(0.5, 0.5, 1, 1)))
     renderer.batch(instances: instances, camera: self.camera)
   }
 

Sources/Voxelotl/GameController.swift

@@ -192,6 +192,8 @@ public extension GameController.Pad.State {
   var rightStick: SIMD2<Float> {
     .init(axis(.rightStickX), axis(.rightStickY))
   }
+  var leftTrigger: Float { axis(.leftTrigger) }
+  var rightTrigger: Float { axis(.rightTrigger) }
 }
 
 public extension FloatingPoint {

Sources/Voxelotl/Player.swift

@@ -1,36 +1,122 @@
 import simd
 
 struct Player {
+  static let height: Float = 1.8
+  static let radius: Float = 0.4
+  static let bounds = AABB(
+    from: .init(-Self.radius, 0, -Self.radius),
+    to: .init(Self.radius, Self.height, Self.radius))
+
+  static let eyeLevel: Float = 1.4
+  static let epsilon = Float.ulpOfOne * 10
+
+  static let speedCoeff: Float = 720
+  static let gravityCoeff: Float = 12
+  static let jumpVelocity: Float = 9
+
   private var _position = SIMD3<Float>.zero
+  private var _velocity = SIMD3<Float>.zero
   private var _rotation = SIMD2<Float>.zero
 
-  public var position: SIMD3<Float> { self._position }
+  private var _onGround: Bool = false
+
+  public var position: SIMD3<Float> { self._position + .init(0, Self.eyeLevel, 0) }
   public var rotation: SIMD2<Float> { self._rotation }
 
-  mutating func update(deltaTime: Float) {
+  mutating func update(deltaTime: Float, boxes: [Box]) {
     if let pad = GameController.current?.state {
+
+      // Turning input
       let turning = pad.rightStick.radialDeadzone(min: 0.1, max: 1)
       _rotation += turning * deltaTime * 3.0
-      if _rotation.x < 0.0 {
-        _rotation.x += .pi * 2
+      if self._rotation.x < 0.0 {
+        self._rotation.x += .pi * 2
       } else if _rotation.x > .pi * 2 {
-        _rotation.x -= .pi * 2
+        self._rotation.x -= .pi * 2
       }
-      _rotation.y = _rotation.y.clamp(-.pi * 0.5, .pi * 0.5)
+      self._rotation.y = self._rotation.y.clamp(-.pi * 0.5, .pi * 0.5)
 
-      let movement = pad.leftStick.cardinalDeadzone(min: 0.1, max: 1)
+      if self._onGround {
+        // Movement on ground
+        let movement = pad.leftStick.cardinalDeadzone(min: 0.1, max: 1)
+        let rotc = cos(self._rotation.x), rots = sin(self._rotation.x)
+        self._velocity.x += (movement.x * rotc - movement.y * rots) * Self.speedCoeff * deltaTime
+        self._velocity.z += (movement.y * rotc + movement.x * rots) * Self.speedCoeff * deltaTime
 
-      let rotc = cos(_rotation.x), rots = sin(_rotation.x)
-      _position += .init(
-        movement.x * rotc - movement.y * rots,
-        0,
-        movement.y * rotc + movement.x * rots
-      ) * deltaTime * 3.0
+        // Jumping
+        if pad.pressed(.east) {
+          self._velocity.y = Self.jumpVelocity
+          self._onGround = false
+        }
+      }
 
+      // Flying
+      self._velocity.y += pad.rightTrigger * 36 * deltaTime
+
+      // Reset
       if pad.pressed(.back) {
-        _position = .zero
-        _rotation = .zero
+        self._position = .zero
+        self._velocity = .zero
+        self._rotation = .zero
+        self._onGround = false
       }
     }
+
+    // Apply gravity
+    self._velocity.y -= Self.gravityCoeff * deltaTime
+
+    // Move & handle collision
+    let checkCollision = { (position: SIMD3<Float>) -> Optional<AABB> in
+      for box in boxes {
+        let bounds = Self.bounds + position
+        if bounds.touching(box.geometry) {
+          return box.geometry
+        }
+      }
+      return nil
+    }
+    self._position.x += _velocity.x * deltaTime
+    if let aabb = checkCollision(self._position) {
+      if _velocity.x < 0 {
+        self._position.x = aabb.right + Self.radius + Self.epsilon
+        printErr("-x")
+      } else {
+        self._position.x = aabb.left - Self.radius - Self.epsilon
+        printErr("+x")
+      }
+      self._velocity.x = 0
+    }
+    self._position.z += _velocity.z * deltaTime
+    if let aabb = checkCollision(self._position) {
+      if _velocity.z < 0 {
+        self._position.z = aabb.near + Self.radius + Self.epsilon
+        printErr("-x")
+      } else {
+        self._position.z = aabb.far - Self.radius - Self.epsilon
+        printErr("+x")
+      }
+      self._velocity.z = 0
+    }
+    self._position.y += _velocity.y * deltaTime
+    if let aabb = checkCollision(self._position) {
+      if _velocity.y < 0 {
+        self._position.y = aabb.top + Self.epsilon
+        if !self._onGround { printErr("-y") }
+        self._onGround = true
+      } else {
+        self._position.y = aabb.bottom - Self.height - Self.epsilon
+        self._onGround = false
+        printErr("+y")
+      }
+      self._velocity.y = 0
+    } else {
+      self._onGround = false
+    }
+
+    // Ground friction
+    if self._onGround {
+      self._velocity.x *= 25 * deltaTime
+      self._velocity.z *= 25 * deltaTime
+    }
   }
 }

Sources/Voxelotl/Renderer.swift

@@ -350,10 +350,10 @@ public class Renderer {
           matrix_float4x4(instance.rotation) *
           .scale(instance.scale),
         color: .init(
-          UInt8(instance.color.x * 0xFF),
-          UInt8(instance.color.y * 0xFF),
-          UInt8(instance.color.z * 0xFF),
-          UInt8(instance.color.w * 0xFF)))
+          UInt8(truncating: NSNumber(value: instance.color.x * 0xFF)),
+          UInt8(truncating: NSNumber(value: instance.color.y * 0xFF)),
+          UInt8(truncating: NSNumber(value: instance.color.z * 0xFF)),
+          UInt8(truncating: NSNumber(value: instance.color.w * 0xFF))))
     }
 
     // Ideal as long as our uniforms total 4 KB or less