Allow floorless leafy link destinations

src/main/java/net/dnorberg/rivencraft/book/LinkingService.java

@@ -4,9 +4,9 @@ import java.util.Comparator;
 import java.util.Optional;
 import java.util.stream.Stream;
 import net.minecraft.core.BlockPos;
-import net.minecraft.core.Direction;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.tags.BlockTags;
 import net.minecraft.world.level.border.WorldBorder;
 import net.minecraft.world.phys.Vec3;
 
@@ -63,12 +63,13 @@ public final class LinkingService {
 
     private static boolean isSafe(ServerLevel level, BlockPos feet) {
         BlockPos head = feet.above();
-        BlockPos floor = feet.below();
-        return level.getBlockState(feet).getCollisionShape(level, feet).isEmpty()
-                && level.getFluidState(feet).isEmpty()
-                && level.getBlockState(head).getCollisionShape(level, head).isEmpty()
-                && level.getFluidState(head).isEmpty()
-                && level.getBlockState(floor).isFaceSturdy(level, floor, Direction.UP);
+        return isPassableSpawnSpace(level, feet) && isPassableSpawnSpace(level, head);
+    }
+
+    private static boolean isPassableSpawnSpace(ServerLevel level, BlockPos position) {
+        var state = level.getBlockState(position);
+        return level.getFluidState(position).isEmpty()
+                && (state.getCollisionShape(level, position).isEmpty() || state.is(BlockTags.LEAVES));
     }
 
     public enum LinkResult {

src/main/java/net/dnorberg/rivencraft/gametest/LinkingGameTests.java

@@ -13,6 +13,7 @@ import net.minecraft.nbt.CompoundTag;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.phys.Vec3;
 import net.neoforged.neoforge.gametest.GameTestHolder;
 import net.neoforged.neoforge.gametest.PrefixGameTestTemplate;
 
@@ -44,8 +45,10 @@ public final class LinkingGameTests {
     }
 
     @GameTest(template = "empty")
-    public static void travelUsesRecordedSafePosition(GameTestHelper helper) {
-        helper.setBlock(ORIGIN.below(), Blocks.STONE);
+    public static void travelUsesLeafyDestinationWithoutFloor(GameTestHelper helper) {
+        helper.setBlock(ORIGIN.below(), Blocks.AIR);
+        helper.setBlock(ORIGIN, Blocks.OAK_LEAVES);
+        helper.setBlock(ORIGIN.above(), Blocks.OAK_LEAVES);
         BlockPos destination = helper.absolutePos(ORIGIN);
         ServerPlayer player = helper.makeMockServerPlayerInLevel();
         LinkTarget target = new LinkTarget(GlobalPos.of(helper.getLevel().dimension(), destination), 90.0F, 15.0F);
@@ -53,8 +56,10 @@ public final class LinkingGameTests {
         LinkingService.LinkResult result = LinkingService.travel(player, target);
 
         helper.assertValueEqual(result, LinkingService.LinkResult.SUCCESS,
-                "A Linking Book must travel to a clear location with a sturdy floor");
+                "A Linking Book must accept leaf blocks even without a floor");
         helper.assertTrue(player.level() == helper.getLevel(), "Travel must remain in the recorded dimension");
+        helper.assertTrue(player.position().distanceToSqr(Vec3.atBottomCenterOf(destination)) < 0.001D,
+                "The recorded leafy destination itself must be selected");
         helper.assertTrue(Math.abs(player.getYRot() - 90.0F) < 0.01F && Math.abs(player.getXRot() - 15.0F) < 0.01F,
                 "Travel must restore the recorded orientation");
         helper.succeed();