From d564cf17e9a1eb5dba8a0b5993fb1995e2f30130 Mon Sep 17 00:00:00 2001
From: asofold <asofold@web.de>
Date: Sat, 7 Mar 2015 03:07:48 +0100
Subject: [PATCH] Attempt to fix a ray-tracing issue.

---
 .../nocheatplus/utilities/RayTracing.java     | 19 ++++++++++++------
 .../nocheatplus/test/TestRayTracing.java      | 20 ++++++++++---------
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/RayTracing.java b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/RayTracing.java
index eb553be1..492b878d 100644
--- a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/RayTracing.java
+++ b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/RayTracing.java
@@ -21,6 +21,9 @@ public abstract class RayTracing {
     /** Current block. */
     protected int blockX, blockY, blockZ;
 
+    /** End block. */
+    protected int endBlockX, endBlockY, endBlockZ;
+
     /** Offset within current block. */
     protected double oX, oY, oZ;
 
@@ -67,6 +70,9 @@ public abstract class RayTracing {
         blockX = Location.locToBlock(x0);
         blockY = Location.locToBlock(y0);
         blockZ = Location.locToBlock(z0);
+        endBlockX = Location.locToBlock(x1);
+        endBlockY = Location.locToBlock(y1);
+        endBlockZ = Location.locToBlock(z1);
         oX = (double) (x0 - blockX);
         oY = (double) (y0 - blockY);
         oZ = (double) (z0 - blockZ);
@@ -74,11 +80,11 @@ public abstract class RayTracing {
         step = 0;
     }
 
-    private static final double tDiff(final double dTotal, final double offset){
+    private static final double tDiff(final double dTotal, final double offset, final int block, final int endBlock){
         if (dTotal > 0.0){
             if (offset >= 1.0) {
                 // Static block change (e.g. diagonal move).
-                return 0.0;
+                return block == endBlock ? Double.MAX_VALUE : 0.0;
             } else {
                 return (1.0 - offset) / dTotal; 
             }
@@ -86,7 +92,7 @@ public abstract class RayTracing {
         else if (dTotal < 0.0){
             if (offset <= 0.0) {
                 // Static block change (e.g. diagonal move).
-                return 0.0;
+                return block == endBlock ? Double.MAX_VALUE : 0.0;
             } else {
                 return offset / -dTotal;
             }
@@ -107,9 +113,9 @@ public abstract class RayTracing {
         boolean changed;
         while (1.0 - t > tol){
             // Determine smallest time to block edge.
-            tX = tDiff(dX, oX);
-            tY = tDiff(dY, oY);
-            tZ = tDiff(dZ, oZ);
+            tX = tDiff(dX, oX, blockX, endBlockX);
+            tY = tDiff(dY, oY, blockY, endBlockY);
+            tZ = tDiff(dZ, oZ, blockZ, endBlockZ);
             tMin = Math.min(tX,  Math.min(tY, tZ));
             if (tMin == Double.MAX_VALUE) {
                 // All differences are 0 (no progress).
@@ -186,6 +192,7 @@ public abstract class RayTracing {
                 break;
             }
         }
+        // TODO: Catch special case with going beyond coordinates.
     }
 
     /**
diff --git a/NCPPlugin/src/test/java/fr/neatmonster/nocheatplus/test/TestRayTracing.java b/NCPPlugin/src/test/java/fr/neatmonster/nocheatplus/test/TestRayTracing.java
index 267bb06d..1644f54a 100644
--- a/NCPPlugin/src/test/java/fr/neatmonster/nocheatplus/test/TestRayTracing.java
+++ b/NCPPlugin/src/test/java/fr/neatmonster/nocheatplus/test/TestRayTracing.java
@@ -14,6 +14,8 @@ import fr.neatmonster.nocheatplus.utilities.build.BuildParameters;
 
 public class TestRayTracing {
 
+    // TODO: Add a test that fails if going beyond target block coordinate.
+
     protected static final Random random = new Random(System.nanoTime() + 13391);
 
     protected static double maxFactor = 9.0;
@@ -90,9 +92,9 @@ public class TestRayTracing {
                 step = 0;
             }
 
-//            private boolean ignEdge(double offset, double dTotal){
-//                return offset == 1 && dTotal > 0 || offset == 0 && dTotal < 0;
-//            }
+            //            private boolean ignEdge(double offset, double dTotal){
+            //                return offset == 1 && dTotal > 0 || offset == 0 && dTotal < 0;
+            //            }
 
             @Override
             protected boolean step(int blockX, int blockY, int blockZ, double oX, double oY, double oZ, double dT) {
@@ -102,13 +104,13 @@ public class TestRayTracing {
                 if (dT < 0.0){
                     doFail("dT < 0 at t = " + StringUtil.fdec3.format(t), coords);
                 }
-                
+
                 // TODO: Check if this check makes sense at all (dT=0 happens during multi-transitions.)l.
-//                if (dT == 0.0 && 1.0 - (t + dT) > tol){
-//                    if (!ignEdge(oX, dX) && !ignEdge(oY, dY) && !ignEdge(oZ, dZ)){
-//                        doFail("Premature dT = 0 at t = " + StringUtil.fdec3.format(t), coords);
-//                    }
-//                }
+                //                if (dT == 0.0 && 1.0 - (t + dT) > tol){
+                //                    if (!ignEdge(oX, dX) && !ignEdge(oY, dY) && !ignEdge(oZ, dZ)){
+                //                        doFail("Premature dT = 0 at t = " + StringUtil.fdec3.format(t), coords);
+                //                    }
+                //                }
 
                 checkOffset(oX, "x");
                 checkOffset(oY, "y");