moving platform wip

assets/mods/basegame/commands.csv

@@ -32,6 +32,7 @@ SetSol
 SetTurb
 SetTime
 SetTimeDelta
+SpawnMovingPlatform
 SpawnPhysTestBall
 Teleport
 ToggleNoClip

src/net/torvald/terrarum/gameactors/ActorMovingPlatform.kt

@@ -1,40 +1,192 @@
 package net.torvald.terrarum.gameactors
 
+import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.Pixmap
+import com.badlogic.gdx.graphics.Texture
+import com.badlogic.gdx.graphics.g2d.SpriteBatch
+import com.badlogic.gdx.graphics.g2d.TextureRegion
+import net.torvald.terrarum.INGAME
 import net.torvald.terrarum.TerrarumAppConfiguration.TILE_SIZE
-import net.torvald.terrarum.gameactors.ActorID
+import net.torvald.terrarum.modulebasegame.gameactors.ActorHumanoid
-import net.torvald.terrarum.gameactors.ActorWithBody
+import org.dyn4j.geometry.Vector2
-import net.torvald.terrarum.gameactors.PhysProperties
 
 /**
+ * Base class for autonomously moving platforms that carry other actors standing on them.
+ *
+ * Subclasses must set [platformVelocity] before calling `super.updateImpl(delta)`.
+ *
  * Created by minjaesong on 2022-02-28.
  */
 open class ActorMovingPlatform() : ActorWithBody() {
 
     protected var tilewiseWidth = 3
-    @Transient protected val actorsRiding = ArrayList<ActorID>() // saving actorID due to serialisation issues
+
+    constructor(newTilewiseWidth: Int) : this() {
+        this.tilewiseWidth = newTilewiseWidth
+    }
+
+    /** Actors currently riding this platform, stored by ActorID for serialisation. */
+    @Transient protected val actorsRiding = ArrayList<ActorID>()
+
+    /** Velocity the platform intends to move this tick. Subclasses set this before calling super.updateImpl(). */
+    @Transient protected val platformVelocity = Vector2(0.0, 0.0)
+
+    /** Actual displacement applied this tick (after clampHitbox). */
+    @Transient private val appliedVelocity = Vector2(0.0, 0.0)
+
+    /** Tolerance in pixels for "feet on top of platform" detection. */
+    @Transient private val MOUNT_TOLERANCE_Y = 2.0
+
+    /** Minimum combined Y velocity to count as "jumping up" (prevents mount while jumping). */
+    @Transient private val JUMP_THRESHOLD_Y = -0.5
+
+    @Transient private var platformTexture: Texture? = null
+    @Transient private var platformTextureRegion: TextureRegion? = null
 
     init {
-        physProp = PhysProperties.PHYSICS_OBJECT()
+        physProp = PhysProperties.MOBILE_OBJECT()
+        collisionType = COLLISION_KINEMATIC
 
         setHitboxDimension(TILE_SIZE * tilewiseWidth, TILE_SIZE, 0, 0)
     }
 
+    private fun ensureTexture() {
+        if (platformTexture == null) {
+            val w = TILE_SIZE * tilewiseWidth
+            val h = TILE_SIZE
+            val pixmap = Pixmap(w, h, Pixmap.Format.RGBA8888)
+            // grey-blue colour
+            pixmap.setColor(Color(0.45f, 0.55f, 0.65f, 1f))
+            pixmap.fill()
+            // slightly darker border
+            pixmap.setColor(Color(0.35f, 0.45f, 0.55f, 1f))
+            pixmap.drawRectangle(0, 0, w, h)
+            platformTexture = Texture(pixmap)
+            platformTextureRegion = TextureRegion(platformTexture)
+            pixmap.dispose()
+        }
+    }
+
     override fun updateImpl(delta: Float) {
-        TODO("Not yet implemented")
+        // Snapshot position before movement
+        val oldX = hitbox.startX
+        val oldY = hitbox.startY
+
+        // Set externalV to our platform velocity so super translates the hitbox
+        externalV.set(platformVelocity.x, platformVelocity.y)
+
+        // super.updateImpl handles:
+        //   - sprite updates
+        //   - hitbox.translate(externalV) (since usePhysics=false -> isNoCollideWorld=true)
+        //   - clampHitbox
+        //   - tilewise hitbox cache updates
+        //   - position vector updates
+        super.updateImpl(delta)
+
+        // Compute actual displacement (clampHitbox may have wrapped coordinates)
+        appliedVelocity.set(hitbox.startX - oldX, hitbox.startY - oldY)
+
+        // --- Mount detection and rider management ---
+
+        val ridersToRemove = ArrayList<ActorID>()
+
+        // Build set of actors currently on top of this platform
+        val newRiders = ArrayList<ActorWithBody>()
+
+        // Check all active actors + actorNowPlaying
+        val candidates = ArrayList<ActorWithBody>()
+        INGAME.actorContainerActive.forEach {
+            if (it is ActorWithBody && it !== this && it !is ActorMovingPlatform) {
+                candidates.add(it)
+            }
+        }
+        INGAME.actorNowPlaying?.let { candidates.add(it) }
+
+        for (actor in candidates) {
+            val feetY = actor.hitbox.endY
+            val platTop = hitbox.startY
+
+            // Check vertical proximity: feet within tolerance of platform top
+            val verticallyAligned = Math.abs(feetY - platTop) <= MOUNT_TOLERANCE_Y
+
+            // Check horizontal overlap
+            val horizontalOverlap = actor.hitbox.endX > hitbox.startX && actor.hitbox.startX < hitbox.endX
+
+            // Check not jumping upward
+            val combinedVelY = actor.externalV.y + (actor.controllerV?.y ?: 0.0)
+            val notJumping = combinedVelY >= JUMP_THRESHOLD_Y
+
+            if (verticallyAligned && horizontalOverlap && notJumping) {
+                if (!actorsRiding.contains(actor.referenceID)) {
+                    mount(actor)
+                }
+                newRiders.add(actor)
+            }
+        }
+
+        // Dismount actors that are no longer on top
+        val newRiderIds = newRiders.map { it.referenceID }.toSet()
+        for (riderId in actorsRiding.toList()) {
+            if (riderId !in newRiderIds) {
+                val rider = INGAME.getActorByID(riderId)
+                if (rider is ActorWithBody) {
+                    dismount(rider)
+                }
+                else {
+                    ridersToRemove.add(riderId)
+                }
+            }
+        }
+        ridersToRemove.forEach { actorsRiding.remove(it) }
+
+        // Move riders and suppress their gravity
+        for (rider in newRiders) {
+            // Translate rider by platform's actual displacement
+            rider.hitbox.translate(appliedVelocity)
+
+            // Snap rider's feet to platform top
+            rider.hitbox.setPositionY(hitbox.startY - rider.hitbox.height)
+
+            // Suppress gravity for this tick
+            rider.walledBottom = true
+        }
     }
 
     /**
-     * Make the actor its externalV controlled by this platform
+     * Add an actor to the rider list.
      */
     fun mount(actor: ActorWithBody) {
+        if (!actorsRiding.contains(actor.referenceID)) {
             actorsRiding.add(actor.referenceID)
+            actor.platformsRiding.add(this.referenceID)
+        }
     }
 
     /**
-     * Make the actor its externalV no longer controlled by this platform
+     * Remove an actor from the rider list and apply dismount impulse.
      */
     fun dismount(actor: ActorWithBody) {
         actorsRiding.remove(actor.referenceID)
+        actor.platformsRiding.remove(this.referenceID)
+
+        // Conservation of momentum: add platform velocity as impulse
+        actor.externalV.x += platformVelocity.x
+        actor.externalV.y += platformVelocity.y
     }
 
+    override fun drawBody(frameDelta: Float, batch: SpriteBatch) {
+        if (isVisible) {
+            ensureTexture()
+            platformTextureRegion?.let {
+                drawTextureInGoodPosition(frameDelta, it, batch)
+            }
+        }
+    }
+
+    override fun dispose() {
+        platformTexture?.dispose()
+        platformTexture = null
+        platformTextureRegion = null
+        super.dispose()
+    }
 }

src/net/torvald/terrarum/gameactors/ActorWithBody.kt

@@ -331,7 +331,7 @@ open class ActorWithBody : Actor {
      *
      * Also see [net.torvald.terrarum.modulebasegame.gameactors.ActorMovingPlatform.actorsRiding]
      */
-    @Transient protected val platformsRiding = ArrayList<ActorID>()
+    @Transient internal val platformsRiding = ArrayList<ActorID>()
 
     /**
      * Gravitational Constant G. Load from gameworld.

src/net/torvald/terrarum/modulebasegame/TerrarumIngame.kt

@@ -1480,8 +1480,16 @@ open class TerrarumIngame(batch: FlippingSpriteBatch) : IngameInstance(batch) {
             actorNowPlaying?.update(delta)*/
         }
         else {
+            // Pass 1: update moving platforms first so riders get displaced before their own update
             actorContainerActive.forEach {
-                if (it != actorNowPlaying) {
+                if (it is ActorMovingPlatform && it != actorNowPlaying) {
+                    it.update(delta)
+                }
+            }
+
+            // Pass 2: update all non-platform actors with existing callbacks
+            actorContainerActive.forEach {
+                if (it !is ActorMovingPlatform && it != actorNowPlaying) {
                     it.update(delta)
 
                     if (it is Pocketed) {
@@ -1515,6 +1523,8 @@ open class TerrarumIngame(batch: FlippingSpriteBatch) : IngameInstance(batch) {
                     }
                 }
             }
+
+            // Pass 3: update player
             actorNowPlaying?.update(delta)
             //AmmoMeterProxy(player, uiVitalItem.UI as UIVitalMetre)
         }

src/net/torvald/terrarum/modulebasegame/console/SpawnMovingPlatform.kt

@@ -0,0 +1,32 @@
+package net.torvald.terrarum.modulebasegame.console
+
+import net.torvald.terrarum.INGAME
+import net.torvald.terrarum.Terrarum
+import net.torvald.terrarum.console.ConsoleAlias
+import net.torvald.terrarum.console.ConsoleCommand
+import net.torvald.terrarum.console.Echo
+import net.torvald.terrarum.modulebasegame.gameactors.ActorTestPlatform
+
+/**
+ * Created by minjaesong on 2026-02-08.
+ */
+@ConsoleAlias("spawnplatform")
+internal object SpawnMovingPlatform : ConsoleCommand {
+    override fun execute(args: Array<String>) {
+        val mouseX = Terrarum.mouseX
+        val mouseY = Terrarum.mouseY
+
+        val platform = ActorTestPlatform()
+        // setPosition places bottom-centre at the given point; offset Y so the platform is centred at cursor
+        platform.setPosition(mouseX, mouseY + platform.hitbox.height / 2.0)
+
+        INGAME.queueActorAddition(platform)
+
+        Echo("Spawned ActorTestPlatform at (${"%.1f".format(mouseX)}, ${"%.1f".format(mouseY)})")
+    }
+
+    override fun printUsage() {
+        Echo("usage: spawnplatform")
+        Echo("Spawns a test moving platform centred at the mouse cursor.")
+    }
+}

src/net/torvald/terrarum/modulebasegame/gameactors/ActorTestPlatform.kt

@@ -1,9 +1,77 @@
 package net.torvald.terrarum.modulebasegame.gameactors
 
 import net.torvald.terrarum.gameactors.ActorMovingPlatform
+import kotlin.math.cos
+import kotlin.math.sin
 
 /**
+ * Test platform that randomly selects a movement pattern on spawn.
+ *
+ * Patterns:
+ * - 0: Horizontal pingpong (sine-eased)
+ * - 1: Vertical pingpong (sine-eased)
+ * - 2: Clockwise circular (constant speed)
+ * - 3: Counter-clockwise circular (constant speed)
+ *
  * Created by minjaesong on 2022-03-02.
  */
-class ActorTestPlatform : ActorMovingPlatform() {
+class ActorTestPlatform : ActorMovingPlatform(8) {
+
+    /** Movement pattern index (0-3). */
+    private val pattern: Int = (0..3).random()
+
+    /** Speed in pixels per tick (2.0 to 4.0). */
+    private val speed: Double = 2.0 + Math.random() * 2.0
+
+    /** Current phase angle in radians. */
+    private var phase: Double = 0.0
+
+    /**
+     * Phase step per tick.
+     *
+     * For pingpong: peak speed = amplitude * phaseStep = speed
+     *   period = 128 ticks (~2s), so phaseStep = 2*PI/128
+     *   amplitude = speed / phaseStep
+     *
+     * For circular: speed = radius * phaseStep
+     *   using same phaseStep, radius = speed / phaseStep
+     */
+    @Transient private val PERIOD_TICKS = 128.0
+    @Transient private val phaseStep: Double = 2.0 * Math.PI / PERIOD_TICKS
+
+    /** Amplitude for pingpong patterns, radius for circular patterns. */
+    @Transient private val amplitude: Double = speed / phaseStep
+
+    override fun updateImpl(delta: Float) {
+        val oldPhase = phase
+        phase += phaseStep
+
+        when (pattern) {
+            0 -> {
+                // Horizontal pingpong: position = A * sin(phase)
+                // Velocity = finite difference to prevent float drift
+                val dx = amplitude * (sin(phase) - sin(oldPhase))
+                platformVelocity.set(dx, 0.0)
+            }
+            1 -> {
+                // Vertical pingpong: position = A * sin(phase)
+                val dy = amplitude * (sin(phase) - sin(oldPhase))
+                platformVelocity.set(0.0, dy)
+            }
+            2 -> {
+                // Clockwise circular: position on circle (cos, sin)
+                val dx = amplitude * (cos(phase) - cos(oldPhase))
+                val dy = amplitude * (sin(phase) - sin(oldPhase))
+                platformVelocity.set(dx, dy)
+            }
+            3 -> {
+                // Counter-clockwise circular: negate Y component
+                val dx = amplitude * (cos(phase) - cos(oldPhase))
+                val dy = -(amplitude * (sin(phase) - sin(oldPhase)))
+                platformVelocity.set(dx, dy)
+            }
+        }
+
+        super.updateImpl(delta)
+    }
 }