CLine: render as a single display shown by view distance

The line no longer needs start, middle and end parts that were moved
around the player. It is one display that is visible for a player as soon
as any chunk the line passes through is in their view distance.
REntity#canView now receives the chunk positions of player and entity.

SpigotCore/SpigotCore_Main/src/de/steamwar/entity/CLine.java

@@ -19,21 +19,23 @@
 
 package de.steamwar.entity;
 
+import lombok.AccessLevel;
 import lombok.Getter;
 import org.bukkit.Location;
 import org.bukkit.block.data.BlockData;
 import org.bukkit.entity.Display;
 import org.bukkit.entity.Player;
-import org.bukkit.util.Consumer;
 import org.bukkit.util.Transformation;
 import org.bukkit.util.Vector;
 import org.joml.Quaternionf;
 import org.joml.Vector3f;
 
 import java.util.Objects;
+import java.util.function.Consumer;
 
 /**
  * Can be used for Axis Aligned Lines of near infinite length.
+ * The line is a single display, which is shown to players based on their view distance.
  */
 @Getter
 public class CLine extends CEntity {
@@ -42,6 +44,8 @@ public class CLine extends CEntity {
     private static final float offset = 1 / 1024f;
     private static final Vector offsetVec = new Vector(offset, offset, offset);
 
+    @Getter(AccessLevel.NONE)
+    private LineDisplay line;
     private Location from;
     private Location to;
     private float width = DEFAULT_WIDTH;
@@ -99,9 +103,7 @@ public class CLine extends CEntity {
         if (hide == this.hide) return;
         this.hide = hide;
         if (hide) {
-            if (startLine != null) startLine.hide(true);
+            if (line != null) line.hide(true);
-            if (middleLine != null) middleLine.hide(true);
-            if (endLine != null) endLine.hide(true);
         } else {
             tick();
         }
@@ -109,148 +111,26 @@ public class CLine extends CEntity {
 
     @Override
     void tick() {
-        if (from == null || to == null) {
+        if (from == null || to == null || hide) {
-            if (startLine != null) startLine.hide(true);
+            if (line != null) line.hide(true);
-            if (middleLine != null) middleLine.hide(true);
-            if (endLine != null) endLine.hide(true);
-            return;
-        } else {
-            if (startLine != null) startLine.hide(false);
-            if (middleLine != null) middleLine.hide(false);
-            if (endLine != null) endLine.hide(false);
-        }
-        if (hide) return;
-        updateStart();
-        updateMiddle();
-        updateEnd();
-    }
-
-    private RBlockDisplay startLine;
-
-    private void updateStart() {
-        Vector vec = to.clone().subtract(from).toVector();
-        if (vec.length() > 35) vec.normalize().multiply(35);
-
-        if (startLine == null) {
-            startLine = new RBlockDisplay(server, new Location(null, 0, 0, 0));
-            startLine.setBrightness(new Display.Brightness(15, 15));
-            startLine.setViewRange(560);
-            startLine.setBlock(blockData);
-            entities.add(startLine);
-        } else {
-            startLine.hide(false);
-        }
-
-        startLine.move(from.clone().subtract(offsetVec));
-        startLine.setTransform(new Transformation(new Vector3f(0, 0, 0), new Quaternionf(0, 0, 0, 1), addWidth(vec).toVector3f(), new Quaternionf(0, 0, 0, 1)));
-    }
-
-    private RBlockDisplay middleLine;
-
-    private void updateMiddle() {
-        Vector vec = to.clone().subtract(from).toVector();
-        if (vec.length() <= 70) {
-            if (middleLine != null) middleLine.hide(true);
             return;
         }
-        if (vec.length() > 280) vec.normalize().multiply(280);
-        else vec = vec.clone().normalize().multiply(vec.length() - 60);
 
-        if (middleLine == null) {
+        if (line == null) {
-            middleLine = new RBlockDisplay(server, new Location(null, 0, 0, 0));
+            line = new LineDisplay(server);
-            middleLine.setBrightness(new Display.Brightness(15, 15));
+            line.setBrightness(new Display.Brightness(15, 15));
-            middleLine.setViewRange(560);
+            line.setViewRange(560);
-            middleLine.setBlock(blockData);
+            line.setBlock(blockData);
-            entities.add(middleLine);
+            entities.add(line);
         } else {
-            middleLine.hide(false);
+            line.hide(false);
         }
 
-        Player player = server.getPlayers().stream().findFirst().orElse(null);
-        if (player == null) return;
-
-        Vector tempVector = vec.clone().normalize().multiply(30);
-        Location from = this.from.clone().add(tempVector);
-        Location to = this.to.clone().subtract(tempVector);
-
-        Vector lineVec = to.clone().subtract(from).toVector();
-        Vector playerVec = player.getLocation().toVector().subtract(from.toVector());
-        double lineVecDotItself = lineVec.dot(lineVec);
-        Vector projectionVec = lineVec.clone().multiply(lineVec.dot(playerVec)).divide(new Vector(lineVecDotItself, lineVecDotItself, lineVecDotItself));
-
-        Vector moveVec = from.toVector().add(projectionVec);
-        if (moveVec.getX() < from.getX()) {
-            moveVec.setX(from.getX());
-        }
-        if (moveVec.getX() > to.getX()) {
-            moveVec.setX(to.getX());
-        }
-        if (moveVec.getY() < from.getY()) {
-            moveVec.setY(from.getY());
-        }
-        if (moveVec.getY() > to.getY()) {
-            moveVec.setY(to.getY());
-        }
-        if (moveVec.getZ() < from.getZ()) {
-            moveVec.setZ(from.getZ());
-        }
-        if (moveVec.getZ() > to.getZ()) {
-            moveVec.setZ(to.getZ());
-        }
-
-        Vector translation = vec.clone().divide(new Vector(2, 2, 2));
-        translation.setX(-translation.getX());
-        translation.setY(-translation.getY());
-        translation.setZ(-translation.getZ());
-
-        Vector first = moveVec.clone().add(translation).subtract(from.toVector());
-        if (first.getX() < 0) {
-            translation.setX(translation.getX() - first.getX());
-        }
-        if (first.getY() < 0) {
-            translation.setY(translation.getY() - first.getY());
-        }
-        if (first.getZ() < 0) {
-            translation.setZ(translation.getZ() - first.getZ());
-        }
-
-        Vector second = to.toVector().subtract(moveVec.clone().subtract(translation));
-        if (second.getX() < 0) {
-            translation.setX(translation.getX() + second.getX());
-        }
-        if (second.getY() < 0) {
-            translation.setY(translation.getY() + second.getY());
-        }
-        if (second.getZ() < 0) {
-            translation.setZ(translation.getZ() + second.getZ());
-        }
-
-        middleLine.move(moveVec.toLocation(player.getWorld()).subtract(offsetVec));
-        middleLine.setTransform(new Transformation(translation.toVector3f(), new Quaternionf(0, 0, 0, 1), addWidth(vec).toVector3f(), new Quaternionf(0, 0, 0, 1)));
-    }
-
-    private RBlockDisplay endLine;
-
-    private void updateEnd() {
         Vector vec = to.clone().subtract(from).toVector();
-        if (vec.length() <= 35) {
+        line.setSpan(from, to);
-            if (endLine != null) endLine.hide(true);
+        line.move(from.clone().subtract(offsetVec));
-            return;
+        line.setTransform(new Transformation(new Vector3f(0, 0, 0), new Quaternionf(0, 0, 0, 1), addWidth(vec).toVector3f(), new Quaternionf(0, 0, 0, 1)));
-        }
+        server.updateViewers(line);
-        if (vec.length() > 35) vec.normalize().multiply(35);
-
-        if (endLine == null) {
-            endLine = new RBlockDisplay(server, new Location(null, 0, 0, 0));
-            endLine.setBrightness(new Display.Brightness(15, 15));
-            endLine.setViewRange(560);
-            endLine.setBlock(blockData);
-            entities.add(endLine);
-        } else {
-            endLine.hide(false);
-        }
-
-        endLine.move(to.clone().subtract(offsetVec));
-        endLine.setTransform(new Transformation(vec.toVector3f().negate(), new Quaternionf(0, 0, 0, 1), addWidth(vec).toVector3f(), new Quaternionf(0, 0, 0, 1)));
     }
 
     private Vector addWidth(Vector vector) {
@@ -267,4 +147,31 @@ public class CLine extends CEntity {
         vector.add(offsetVec).add(offsetVec);
         return vector;
     }
+
+    /**
+     * The line is one display that is visible for a player as soon as any chunk it passes through is in the view distance,
+     * independent of the chunk its origin is in.
+     */
+    private static class LineDisplay extends RBlockDisplay {
+
+        private int minChunkX, maxChunkX, minChunkZ, maxChunkZ;
+
+        private LineDisplay(REntityServer server) {
+            super(server, new Location(null, 0, 0, 0));
+        }
+
+        private void setSpan(Location from, Location to) {
+            minChunkX = Math.floorDiv((int) Math.floor(Math.min(from.getX(), to.getX())), 16);
+            maxChunkX = Math.floorDiv((int) Math.floor(Math.max(from.getX(), to.getX())), 16);
+            minChunkZ = Math.floorDiv((int) Math.floor(Math.min(from.getZ(), to.getZ())), 16);
+            maxChunkZ = Math.floorDiv((int) Math.floor(Math.max(from.getZ(), to.getZ())), 16);
+        }
+
+        @Override
+        protected boolean canView(Player player, int playerChunkX, int playerChunkZ, int entityChunkX, int entityChunkZ) {
+            int distanceX = Math.max(0, Math.max(minChunkX - playerChunkX, playerChunkX - maxChunkX));
+            int distanceZ = Math.max(0, Math.max(minChunkZ - playerChunkZ, playerChunkZ - maxChunkZ));
+            return inViewDistance(player, Math.max(distanceX, distanceZ));
+        }
+    }
 }

SpigotCore/SpigotCore_Main/src/de/steamwar/entity/RDisplay.java

@@ -143,8 +143,8 @@ public abstract class RDisplay extends REntity {
      * A view range of 1 equals 64 blocks. This is only a comparison, so huge values like {@link Float#MAX_VALUE} are cheap.
      */
     @Override
-    protected boolean canView(Player player, int chunkDistance) {
+    protected boolean canView(Player player, int playerChunkX, int playerChunkZ, int entityChunkX, int entityChunkZ) {
-        return chunkDistance <= Math.ceil(viewRange * 64.0 / 16.0);
+        return chunkDistance(playerChunkX, playerChunkZ, entityChunkX, entityChunkZ) <= Math.ceil(viewRange * 64.0 / 16.0);
     }
 
     private static final EntityDataAccessor<Float> viewRangeWatcher = new EntityDataAccessor<>(17, EntityDataSerializers.FLOAT);

SpigotCore/SpigotCore_Main/src/de/steamwar/entity/REntity.java

@@ -129,9 +129,21 @@ public class REntity {
      * Whether the given player should see this entity.
      * Defaults to the view distance of the player.
      *
-     * @param chunkDistance the larger of the chunk distances between the player and the entity on the x and z axis
+     * @param playerChunkX the chunk the player is in
+     * @param entityChunkX the chunk the entity is in, the entity itself might not be moved there yet
      */
-    protected boolean canView(Player player, int chunkDistance) {
+    protected boolean canView(Player player, int playerChunkX, int playerChunkZ, int entityChunkX, int entityChunkZ) {
+        return inViewDistance(player, chunkDistance(playerChunkX, playerChunkZ, entityChunkX, entityChunkZ));
+    }
+
+    /**
+     * @return the larger of the chunk distances on the x and z axis
+     */
+    protected static int chunkDistance(int chunkX1, int chunkZ1, int chunkX2, int chunkZ2) {
+        return Math.max(Math.abs(chunkX1 - chunkX2), Math.abs(chunkZ1 - chunkZ2));
+    }
+
+    protected boolean inViewDistance(Player player, int chunkDistance) {
         return chunkDistance <= server.viewRadius(player);
     }
 

SpigotCore/SpigotCore_Main/src/de/steamwar/entity/REntityServer.java

@@ -227,8 +227,7 @@ public class REntityServer implements Listener {
 
     private boolean inView(REntity entity, Player player, int entityChunkX, int entityChunkZ) {
         Location location = lastLocation.get(player);
-        int distance = Math.max(Math.abs(posToChunk(location.getX()) - entityChunkX), Math.abs(posToChunk(location.getZ()) - entityChunkZ));
+        return entity.canView(player, posToChunk(location.getX()), posToChunk(location.getZ()), entityChunkX, entityChunkZ);
-        return entity.canView(player, distance);
     }
 
     private void showTo(REntity entity, Player player) {