Fix issue where rotating the ship sometimes causes blocks to rotate in odd ways (#315)

* add kotlin for forge to build.gradle so forge can build

* use ship rotation instead of buggy `aligningTo`

* update shipAssembler to take a rotation
and make snapRotation public

* move logic into ShipAssembler

* remove buggy aligningTo, demote alignTarget to a local

* fix float comparisons

* Removed unnecessary imports (millennIumAMbiguity)

---------

Co-authored-by: millennIumAMbiguity <37588844+millennIumAMbiguity@users.noreply.github.com>

Author: PROMETHIA-27

build.gradle

@@ -99,6 +99,10 @@ allprojects {
 
     repositories {
         mavenLocal()
+        maven {
+            name = 'Kotlin for Forge'
+            url = 'https://thedarkcolour.github.io/KotlinForForge/'
+        }
         maven {
             name = "Valkyrien Skies Internal"
             url = project.vs_maven_url ?: 'https://maven.valkyrienskies.org'

common/src/main/kotlin/org/valkyrienskies/eureka/blockentity/ShipHelmBlockEntity.kt

@@ -84,7 +84,6 @@ class ShipHelmBlockEntity(pos: BlockPos, state: BlockState) :
     }
 
     fun startRiding(player: Player, force: Boolean, blockPos: BlockPos, state: BlockState, level: ServerLevel): Boolean {
-
         for (i in seats.size - 1 downTo 0) {
             if (!seats[i].isVehicle) {
                 seats[i].kill()
@@ -126,7 +125,7 @@ class ShipHelmBlockEntity(pos: BlockPos, state: BlockState) :
         ) { !it.isAir && !EurekaConfig.SERVER.blockBlacklist.contains(BuiltInRegistries.BLOCK.getKey(it.block).toString()) }
 
         if (builtShip == null) {
-            player.displayClientMessage(Component.translatable("Ship is too big! Max size is ${EurekaConfig.SERVER.maxShipBlocks} blocks (changable in the config)"), true)
+            player.displayClientMessage(Component.translatable("Ship is too big! Max size is ${EurekaConfig.SERVER.maxShipBlocks} blocks (changeable in the config)"), true)
             logger.warn("Failed to assemble ship for ${player.name.string}")
         }
     }
@@ -148,7 +147,6 @@ class ShipHelmBlockEntity(pos: BlockPos, state: BlockState) :
         ShipAssembler.unfillShip(
             level as ServerLevel,
             ship,
-            control.aligningTo,
             this.blockPos,
             BlockPos.containing(inWorld.x, inWorld.y, inWorld.z)
         )
@@ -163,7 +161,6 @@ class ShipHelmBlockEntity(pos: BlockPos, state: BlockState) :
     }
 
     override fun setRemoved() {
-
         if (level?.isClientSide == false) {
             for (i in seats.indices) {
                 seats[i].kill()

common/src/main/kotlin/org/valkyrienskies/eureka/ship/EurekaShipControl.kt

@@ -50,13 +50,11 @@ class EurekaShipControl : ShipForcesInducer, ServerTickListener {
 
     private var angleUntilAligned = 0.0
     private var positionUntilAligned = Vector3d()
-    private var alignTarget = 0
     val canDisassemble
         get() = ship != null &&
             disassembling &&
             abs(angleUntilAligned) < DISASSEMBLE_THRESHOLD &&
             positionUntilAligned.distanceSquared(this.ship!!.transform.positionInWorld) < 4.0
-    val aligningTo: Direction get() = Direction.from2DDataValue(alignTarget)
     var consumed = 0f
         private set
 
@@ -132,7 +130,7 @@ class EurekaShipControl : ShipForcesInducer, ServerTickListener {
         val invRotation = physShip.poseVel.rot.invert(Quaterniond())
         val invRotationAxisAngle = AxisAngle4d(invRotation)
         // Floor makes a number 0 to 3, which corresponds to direction
-        alignTarget = floor((invRotationAxisAngle.angle / (PI * 0.5)) + 4.5).toInt() % 4
+        val alignTarget = floor((invRotationAxisAngle.angle / (PI * 0.5)) + 4.5).toInt() % 4
         angleUntilAligned = (alignTarget.toDouble() * (0.5 * PI)) - invRotationAxisAngle.angle
         if (disassembling) {
             val pos = ship.transform.positionInWorld

common/src/main/kotlin/org/valkyrienskies/eureka/util/ShipAssembler.kt

@@ -26,10 +26,7 @@ import org.valkyrienskies.mod.util.logger
 import org.valkyrienskies.mod.util.relocateBlock
 import org.valkyrienskies.mod.util.updateBlock
 import kotlin.collections.set
-import kotlin.math.PI
-import kotlin.math.abs
-import kotlin.math.round
-import kotlin.math.sign
+import kotlin.math.*
 
 object ShipAssembler {
     fun collectBlocks(level: ServerLevel, center: BlockPos, predicate: (BlockState) -> Boolean): ServerShip? {
@@ -62,9 +59,44 @@ object ShipAssembler {
         }
     }
 
-    fun unfillShip(level: ServerLevel, ship: ServerShip, direction: Direction, shipCenter: BlockPos, center: BlockPos) {
+    private fun rotationFromAxisAngle(axis: AxisAngle4d): Rotation {
+        if (axis.y.absoluteValue < 0.1) {
+            // if the axis isn't Y, either we're tilted up/down (which should not happen often) or we haven't moved and it's
+            // along the z axis with a magnitude of 0 for some reason. In these cases, we don't rotate.
+            return Rotation.NONE
+        }
+
+        // normalize into counterclockwise rotation (i.e. positive y-axis, according to testing + right hand rule)
+        if (axis.y.sign < 0.0) {
+            axis.y = 1.0
+            // the angle is always positive and < 2pi coming in
+            axis.angle = 2.0 * PI - axis.angle
+            axis.angle %= (2.0 * PI)
+        }
+
+        val eps = 0.001
+        if (axis.angle < eps)
+            return Rotation.NONE
+        else if ((axis.angle - PI / 2.0).absoluteValue < eps)
+            return Rotation.COUNTERCLOCKWISE_90
+        else if ((axis.angle - PI).absoluteValue < eps)
+            return Rotation.CLOCKWISE_180
+        else if ((axis.angle - 3.0 * PI / 2.0).absoluteValue < eps)
+            return Rotation.CLOCKWISE_90
+        else {
+            logger.warn("failed to convert $axis into a rotation")
+            return Rotation.NONE
+        }
+    }
+
+    fun unfillShip(level: ServerLevel, ship: ServerShip, shipCenter: BlockPos, center: BlockPos) {
         ship.isStatic = true
 
+        val rotation: Rotation = ship.transform.shipToWorldRotation
+            .let(::AxisAngle4d)
+            .let(ShipAssembler::snapRotation)
+            .let(::rotationFromAxisAngle)
+
         // ship's rotation rounded to nearest 90*
         val shipToWorld = ship.transform.run {
             Matrix4d()
@@ -76,18 +108,6 @@ object ShipAssembler {
 
         val alloc0 = Vector3d()
 
-        // Direction comes from direction ship is aligning to
-        // We can assume that the ship in shipspace is always facing north, because it has to be
-        val rotation: Rotation = when (direction) {
-            Direction.SOUTH -> Rotation.NONE // Bug in Direction.from2DDataValue() can return south/north as opposite
-            Direction.NORTH -> Rotation.CLOCKWISE_180
-            Direction.EAST -> Rotation.CLOCKWISE_90
-            Direction.WEST -> Rotation.COUNTERCLOCKWISE_90
-            else -> {
-                Rotation.NONE
-            }
-        }
-
         val chunksToBeUpdated = mutableMapOf<ChunkPos, Pair<ChunkPos, ChunkPos>>()
 
         ship.activeChunksSet.forEach { chunkX, chunkZ ->