Add heuristic InteractRayTracing.

NCPCompat/src/main/java/fr/neatmonster/nocheatplus/utilities/InteractRayTracing.java

@@ -0,0 +1,149 @@
+package fr.neatmonster.nocheatplus.utilities;
+
+import org.bukkit.Location;
+
+/**
+ * Rough ray-tracing for interaction with something.
+ * @author mc_dev
+ *
+ */
+public class InteractRayTracing extends RayTracing {
+	
+	private static final int[][] incr = new int[][]{
+		{1, 0, 0},
+		{0, 1, 0},
+		{0, 0, 1},
+		{-1, 0, 0},
+		{0, -1, 0},
+		{0, 0, -1},
+	};
+	
+	protected BlockCache blockCache = null;
+	
+	protected boolean collides = false;
+	
+	protected boolean strict = false;
+	
+	protected int lastBx, lastBy, lastBz;
+	
+	protected int targetBx, targetBy, targetBz;
+	
+	public InteractRayTracing(){
+		super();
+	}
+	
+	public InteractRayTracing(boolean strict){
+		super();
+		this.strict = strict;
+	}
+	
+	public BlockCache getBlockCache() {
+		return blockCache;
+	}
+
+	public void setBlockCache(BlockCache blockCache) {
+		this.blockCache = blockCache;
+	}
+	
+	/* (non-Javadoc)
+	 * @see fr.neatmonster.nocheatplus.utilities.RayTracing#set(double, double, double, double, double, double)
+	 */
+	@Override
+	public void set(double x0, double y0, double z0, double x1, double y1, double z1) {
+		super.set(x0, y0, z0, x1, y1, z1);
+		collides = false;
+		lastBx = blockX;
+		lastBy = blockY;
+		lastBz = blockZ;
+		targetBx = Location.locToBlock(x1);
+		targetBy = Location.locToBlock(y1);
+		targetBz = Location.locToBlock(z1);
+	}
+	
+	public boolean collides(){
+		return collides;
+	}
+
+	/**
+	 * Remove reference to BlockCache.
+	 */
+	public void cleanup(){
+		if (blockCache != null){
+			blockCache = null;
+		}
+	}
+	
+	/**
+	 * Simplistic collision check (can interact through this block).
+	 * @param blockX
+	 * @param blockY
+	 * @param blockZ
+	 * @return
+	 */
+	private final boolean doesCollide(int blockX, int blockY, int blockZ){
+		final int id = blockCache.getTypeId(blockX, blockY, blockZ);
+		final long flags = BlockProperties.getBlockFlags(id);
+		if ((flags & BlockProperties.F_SOLID) == 0){
+			// Ignore non solid blocks anyway.
+			return false;
+		}
+		if ((flags & (BlockProperties.F_LIQUID | BlockProperties.F_IGN_PASSABLE | BlockProperties.F_STAIRS | BlockProperties.F_VARIABLE)) != 0){
+			// Special cases.
+			// TODO: F_VARIABLE: Bounding boxes are roughly right ?
+			return false;
+		}
+		if (!blockCache.isFullBounds(blockX, blockY, blockZ)) return false;
+		return true;
+	}
+	
+	/**
+	 * Check if the block may be interacted through by use of some workaround.
+	 * @param blockX
+	 * @param blockY
+	 * @param blockZ
+	 * @return
+	 */
+	private final boolean allowsWorkaround(final int blockX, final int blockY, final int blockZ) {
+		// TODO: This allows some bypasses for "strange" setups.
+		for (int i = 0; i < 6; i++){
+			final int[] dir = incr[i];
+			final int rX = lastBx + dir[0];
+			if (Math.abs(blockX - rX) > 1) continue;
+			final int rY = lastBy + dir[1];
+			if (Math.abs(blockY - rY) > 1) continue;
+			final int rZ = lastBz + dir[2];
+			if (Math.abs(blockZ - rZ) > 1) continue;
+			if (!doesCollide(rX, rY, rZ)){
+				// NOTE: Don't check "rX == targetBx && rZ == targetBz && rY == targetBy".
+				return true;
+			}
+		}
+		return false;
+	}
+	
+	@Override
+	protected boolean step(int blockX, int blockY, int blockZ, double oX, double oY, double oZ, double dT) {
+		// TODO: Make an optional, more precise check (like passable) ?
+		if (blockX == targetBx && blockZ == targetBz && blockY == targetBy || !doesCollide(blockX, blockY, blockZ)){
+			lastBx = blockX;
+			lastBy = blockY;
+			lastBz = blockZ;
+			return true;
+		}
+		if (strict || blockX == lastBx && blockZ == lastBz && blockY == lastBy){
+			collides = true;
+			return false;
+		}
+		// Check workarounds...
+		if (allowsWorkaround(blockX, blockY, blockZ)){
+			lastBx = blockX;
+			lastBy = blockY;
+			lastBz = blockZ;
+			return true;
+		}
+		// No workaround found.
+		collides = true;
+		return false;
+	}
+
+}