From 4fd834ed25f3f4122dca17307ebcb74b8f51300f Mon Sep 17 00:00:00 2001
From: asofold <asofold@web.de>
Date: Sun, 8 Nov 2015 23:36:10 +0100
Subject: [PATCH] Workarounds for moving down (-stream) in lava.

---
 .../nocheatplus/checks/moving/SurvivalFly.java | 18 ++++++++++++++++--
 .../nocheatplus/utilities/BlockProperties.java | 14 ++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
index a190b9b3..1c961528 100644
--- a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
+++ b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/moving/SurvivalFly.java
@@ -84,7 +84,7 @@ public class SurvivalFly extends Check {
     /** Friction for water (default). */
     public static final double FRICTION_MEDIUM_WATER = 0.89;
     /** Friction for lava. */
-    public static final double FRICTION_MEDIUM_LAVA = 0.25; // TODO
+    public static final double FRICTION_MEDIUM_LAVA = 0.25; // TODO: Rather 0.4 ?
 
     // TODO: Friction by block to walk on (horizontal only, possibly to be in BlockProperties rather).
 
@@ -1595,7 +1595,7 @@ public class SurvivalFly extends Check {
         data.sfNoLowJump = true;
 
         // Expected envelopes.
-        final double baseSpeed = swimBaseSpeedV();
+        final double baseSpeed = swimBaseSpeedV(); // TODO: Lava?
         final double yDistAbs = Math.abs(yDistance);
 
         // TODO: Later also cover things like a sudden stop.
@@ -1658,6 +1658,20 @@ public class SurvivalFly extends Check {
                     ) {
                 return new double[]{yDistance, 0.0};
             }
+            // Lava rather.
+            else if (data.lastFrictionVertical < 0.65 // (Random, but smaller than water.) 
+                    && (
+                            // Moving downstream.
+                            data.lastYDist < 0.0 && yDistance > -0.5 && yDistance < data.lastYDist 
+                            && data.lastYDist - yDistance < GRAVITY_MIN && BlockProperties.isDownStream(from, to)
+                            // Mix of gravity and base speed [careful: relates to water base speed].
+                            || data.lastYDist < 0.0 && yDistance > -baseSpeed - GRAVITY_MAX && yDistance < data.lastYDist
+                            && data.lastYDist - yDistance > GRAVITY_SPAN
+                            && Math.abs(data.lastYDist + baseSpeed) < 0.25 * baseSpeed
+                            )
+                    ) {
+                return new double[]{yDistance, 0.0};
+            }
         }
 
         // TODO: Also DOWNSTREAM !?
diff --git a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/BlockProperties.java b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/BlockProperties.java
index d3bf32c6..ec3253d5 100644
--- a/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/BlockProperties.java
+++ b/NCPCore/src/main/java/fr/neatmonster/nocheatplus/utilities/BlockProperties.java
@@ -2658,6 +2658,20 @@ public class BlockProperties {
         return true;
     }
 
+    /**
+     * Check if the move given by from and to is leading downstream. Currently
+     * only the x-z move is regarded, no envelope/consistency checks are
+     * performed here, such as checking if the block is liquid at all, nor if
+     * the move makes sense. performed here.
+     * 
+     * @param from
+     * @param to
+     * @return
+     */
+    public static final boolean isDownStream(final PlayerLocation from, final PlayerLocation to) {
+        return isDownStream(from.getBlockCache(), from.getBlockX(), from.getBlockY(), from.getBlockZ(), from.getData(), to.getX() - from.getX(), to.getZ() - from.getZ());
+    }
+
     /**
      * Check if a move determined by xDistance and zDistance is leading down stream.
      * @param access