5 files changed, 223 insertions, 0 deletions
diff --git a/src/main/kotlin/Camera.kt b/src/main/kotlin/Camera.kt
new file mode 100644
index 0000000..7d4bcfc
--- /dev/null
+++ b/src/main/kotlin/Camera.kt
@@ -0,0 +1,8 @@
+class Camera(
+  val fov: Int,
+  var xPos: Double,
+  var yPos: Double,
+  var rotation: Double
+) {
+  val halfFov = fov / 2
+}
+\ No newline at end of file
diff --git a/src/main/kotlin/Minimap.kt b/src/main/kotlin/Minimap.kt
new file mode 100644
index 0000000..dc7cc91
--- /dev/null
+++ b/src/main/kotlin/Minimap.kt
@@ -0,0 +1,57 @@
+import kotlinx.browser.document
+import org.w3c.dom.CanvasRenderingContext2D
+import org.w3c.dom.HTMLCanvasElement
+
+class Minimap(private val map: List<List<Int>>) {
+
+  private val scale = 30
+  private val mapWidth = map[0].size
+  private val mapHeight = map.size
+
+  private val canvas = (document.createElement("canvas") as HTMLCanvasElement)
+    .apply {
+      width = mapWidth * scale
+      height = mapHeight * scale
+      id = "minimap"
+      style.width = "${width}px"
+      style.height = "${height}px"
+    }
+  private val context = canvas.getContext("2d") as CanvasRenderingContext2D
+
+  init {
+    document.body!!.appendChild(canvas)
+  }
+
+  private fun drawMap() {
+    for (y in 0 until mapHeight) {
+      for (x in 0 until mapWidth) {
+        val wall = map[y][x]
+        if (wall > 0) {
+          context.fillStyle = "#000000"
+          context.fillRect((x * scale).toDouble(), (y * scale).toDouble(), scale.toDouble(), scale.toDouble())
+        }
+      }
+    }
+  }
+
+  fun update(camera: Camera) {
+    context.clearRect(0.0, 0.0, (mapWidth * scale).toDouble(), (mapHeight * scale).toDouble())
+    drawMap()
+    context.fillStyle = "#FF0000"
+    context.fillRect(camera.xPos * scale, camera.yPos * scale, scale.toDouble(), scale.toDouble())
+
+    context.strokeStyle = "#00FF00"
+    context.lineWidth = 2.0
+    context.beginPath()
+    context.moveTo(camera.xPos * scale, camera.yPos * scale)
+
+    val cameraCos = kotlin.math.cos(toRadians(camera.rotation)) * 4
+    val cameraSin = kotlin.math.sin(toRadians(camera.rotation)) * 4
+
+    val dirX = camera.xPos + cameraCos
+    val dirY = camera.yPos + cameraSin
+
+    context.lineTo(dirX * scale, dirY * scale)
+    context.stroke()
+  }
+}
+\ No newline at end of file
diff --git a/src/main/kotlin/Renderer.kt b/src/main/kotlin/Renderer.kt
new file mode 100644
index 0000000..b266e61
--- /dev/null
+++ b/src/main/kotlin/Renderer.kt
@@ -0,0 +1,31 @@
+import kotlinx.browser.document
+import org.w3c.dom.CanvasRenderingContext2D
+import org.w3c.dom.HTMLCanvasElement
+
+class Renderer(val w: Int, val h: Int) {
+
+  private val canvas = (document.createElement("canvas") as HTMLCanvasElement)
+    .apply {
+      width = w
+      height = h
+    }
+  private val context = canvas.getContext("2d") as CanvasRenderingContext2D
+
+  init {
+    document.body!!.appendChild(canvas)
+  }
+
+  fun drawLine(startX: Int, startY: Int, endX: Int, endY: Int, cssColour: String = "#FF0000") {
+    context.strokeStyle = cssColour
+    context.lineWidth = 4.0
+    context.beginPath()
+    context.moveTo(startX.toDouble(), startY.toDouble())
+    context.lineTo(endX.toDouble(), endY.toDouble())
+    context.stroke()
+  }
+
+  fun clear() {
+    context.clearRect(0.0, 0.0, w.toDouble(), h.toDouble())
+  }
+
+}
+\ No newline at end of file
diff --git a/src/main/kotlin/raycaster.kt b/src/main/kotlin/raycaster.kt
new file mode 100644
index 0000000..5b717bc
--- /dev/null
+++ b/src/main/kotlin/raycaster.kt
@@ -0,0 +1,117 @@
+import kotlinx.browser.document
+import kotlin.math.pow
+
+private const val SCREEN_WIDTH = 640
+private const val SCREEN_HEIGHT = 480
+private const val MOVE_SPEED = 0.5
+private const val ROTATE_SPEED = 5
+
+private val map = listOf(
+  listOf(1,1,1,1,1,1,1,1,1,1),
+  listOf(1,0,0,0,0,0,0,0,0,1),
+  listOf(1,0,0,0,0,0,0,0,0,1),
+  listOf(1,0,0,1,1,0,1,0,0,1),
+  listOf(1,0,0,1,0,0,1,0,0,1),
+  listOf(1,0,0,1,0,0,1,0,0,1),
+  listOf(1,0,0,1,0,1,1,0,0,1),
+  listOf(1,0,0,0,0,0,0,0,0,1),
+  listOf(1,0,0,0,0,0,0,0,0,1),
+  listOf(1,1,1,1,1,1,1,1,1,1)
+)
+
+data class RaycastContext(
+  val renderer: Renderer,
+  val camera: Camera,
+  val minimap: Minimap
+)
+
+fun main() {
+  val renderer = Renderer(SCREEN_WIDTH, SCREEN_HEIGHT)
+  val camera = Camera(
+    fov = 60,
+    xPos = 2.0,
+    yPos = 2.0,
+    rotation = 90.0
+  )
+  val minimap = Minimap(map)
+
+  val context = RaycastContext(renderer, camera, minimap)
+
+  document.onkeydown = {
+    when (it.code) {
+      "KeyW" -> {
+        console.log("key w")
+        val cameraCos = kotlin.math.cos(toRadians(camera.rotation)) * MOVE_SPEED
+        val cameraSin = kotlin.math.sin(toRadians(camera.rotation)) * MOVE_SPEED
+        camera.xPos += cameraCos
+        camera.yPos += cameraSin
+      }
+      "KeyS" -> {
+        console.log("key s")
+        val cameraCos = kotlin.math.cos(toRadians(camera.rotation)) * MOVE_SPEED
+        val cameraSin = kotlin.math.sin(toRadians(camera.rotation)) * MOVE_SPEED
+        camera.xPos -= cameraCos
+        camera.yPos -= cameraSin
+      }
+      "KeyA" -> {
+        console.log("key a")
+        camera.rotation -= ROTATE_SPEED
+      }
+      "KeyD" -> {
+        console.log("key d")
+        camera.rotation += ROTATE_SPEED
+      }
+    }
+    paint(context)
+    console.log("camera x:${camera.xPos} y:${camera.yPos} r: ${camera.rotation}")
+  }
+
+  paint(context)
+}
+
+fun paint(raycastContext: RaycastContext) {
+  raycastContext.renderer.clear()
+  raycast(raycastContext)
+  raycastContext.minimap.update(raycastContext.camera)
+}
+
+fun raycast(raycastContext: RaycastContext) {
+  val incrementAngle : Double = raycastContext.camera.fov / SCREEN_WIDTH.toDouble()
+  val rayCastPrecision = 32
+
+  var rayAngle = raycastContext.camera.rotation - raycastContext.camera.halfFov
+
+  for (rayIndex in 0 until SCREEN_WIDTH) {
+
+    var rayX = raycastContext.camera.xPos
+    var rayY = raycastContext.camera.yPos
+
+    val rayCos = kotlin.math.cos(toRadians(rayAngle)) / rayCastPrecision
+    val raySin = kotlin.math.sin(toRadians(rayAngle)) / rayCastPrecision
+
+    var isWall = false
+    while(!isWall) {
+      rayX += rayCos
+      rayY += raySin
+
+      // TODO bounds checking
+      val foo = map[kotlin.math.floor(rayY).toInt()][kotlin.math.floor(rayX).toInt()]
+      if (foo == 1) {
+        isWall = true
+      }
+    }
+
+    val distance = kotlin.math.sqrt((raycastContext.camera.xPos - rayX).pow(2) + (raycastContext.camera.yPos - rayY).pow(2))
+    val wallHeight = kotlin.math.floor((SCREEN_HEIGHT/2) / distance).toInt()
+
+    raycastContext.renderer.drawLine(rayIndex, 0, rayIndex, (SCREEN_HEIGHT/2)-wallHeight, "cyan")
+    raycastContext.renderer.drawLine(rayIndex, (SCREEN_HEIGHT/2)-wallHeight, rayIndex, (SCREEN_HEIGHT/2)+wallHeight, "red")
+    raycastContext.renderer.drawLine(rayIndex, (SCREEN_HEIGHT/2)+wallHeight, rayIndex, SCREEN_HEIGHT, "green")
+
+    rayAngle += incrementAngle
+  }
+}
+
+fun toRadians(degrees: Double): Double {
+  return degrees * kotlin.math.PI / 180
+}
diff --git a/src/main/resources/index.html b/src/main/resources/index.html
new file mode 100644
index 0000000..787422b
--- /dev/null
+++ b/src/main/resources/index.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8">
+    <title>Kotlin Raycaster</title>
+  </head>
+  <body>
+    <script src="kotlin-raycaster.js"></script>
+  </body>
+</html>