From df0a8574dcef24e5a12a366cb10f7ac5d69a8b79 Mon Sep 17 00:00:00 2001
From: rubenwardy <rw@rubenwardy.com>
Date: Fri, 22 Dec 2017 10:00:57 +0000
Subject: Fix rounding error in g/set_node caused by truncation to float

---
 src/irr_v3d.h                     |  1 +
 src/script/common/c_converter.cpp | 46 +++++++++++++++++++++++++++++++++++----
 src/util/numeric.h                | 11 ++++++++++
 3 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/src/irr_v3d.h b/src/irr_v3d.h
index fa6af3661..3a8d1fd30 100644
--- a/src/irr_v3d.h
+++ b/src/irr_v3d.h
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <vector3d.h>
 
 typedef core::vector3df v3f;
+typedef core::vector3d<double> v3d;
 typedef core::vector3d<s16> v3s16;
 typedef core::vector3d<u16> v3u16;
 typedef core::vector3d<s32> v3s32;
diff --git a/src/script/common/c_converter.cpp b/src/script/common/c_converter.cpp
index fc516d56a..d9b926e3e 100644
--- a/src/script/common/c_converter.cpp
+++ b/src/script/common/c_converter.cpp
@@ -196,6 +196,44 @@ v3f check_v3f(lua_State *L, int index)
 	return pos;
 }
 
+v3d read_v3d(lua_State *L, int index)
+{
+	v3d pos;
+	CHECK_POS_TAB(index);
+	lua_getfield(L, index, "x");
+	pos.X = lua_tonumber(L, -1);
+	lua_pop(L, 1);
+	lua_getfield(L, index, "y");
+	pos.Y = lua_tonumber(L, -1);
+	lua_pop(L, 1);
+	lua_getfield(L, index, "z");
+	pos.Z = lua_tonumber(L, -1);
+	lua_pop(L, 1);
+	return pos;
+}
+
+v3d check_v3d(lua_State *L, int index)
+{
+	v3d pos;
+	CHECK_POS_TAB(index);
+	lua_getfield(L, index, "x");
+	CHECK_POS_COORD("x");
+	pos.X = lua_tonumber(L, -1);
+	CHECK_FLOAT_RANGE(pos.X, "x")
+	lua_pop(L, 1);
+	lua_getfield(L, index, "y");
+	CHECK_POS_COORD("y");
+	pos.Y = lua_tonumber(L, -1);
+	CHECK_FLOAT_RANGE(pos.Y, "y")
+	lua_pop(L, 1);
+	lua_getfield(L, index, "z");
+	CHECK_POS_COORD("z");
+	pos.Z = lua_tonumber(L, -1);
+	CHECK_FLOAT_RANGE(pos.Z, "z")
+	lua_pop(L, 1);
+	return pos;
+}
+
 void push_ARGB8(lua_State *L, video::SColor color)
 {
 	lua_newtable(L);
@@ -234,15 +272,15 @@ void push_v3s16(lua_State *L, v3s16 p)
 v3s16 read_v3s16(lua_State *L, int index)
 {
 	// Correct rounding at <0
-	v3f pf = read_v3f(L, index);
-	return floatToInt(pf, 1.0);
+	v3d pf = read_v3d(L, index);
+	return doubleToInt(pf, 1.0);
 }
 
 v3s16 check_v3s16(lua_State *L, int index)
 {
 	// Correct rounding at <0
-	v3f pf = check_v3f(L, index);
-	return floatToInt(pf, 1.0);
+	v3d pf = check_v3d(L, index);
+	return doubleToInt(pf, 1.0);
 }
 
 bool read_color(lua_State *L, int index, video::SColor *color)
diff --git a/src/util/numeric.h b/src/util/numeric.h
index 4a27f657d..573f03788 100644
--- a/src/util/numeric.h
+++ b/src/util/numeric.h
@@ -254,6 +254,17 @@ inline v3s16 floatToInt(v3f p, f32 d)
 		(p.Z + (p.Z > 0 ? d / 2 : -d / 2)) / d);
 }
 
+/*
+	Returns integer position of node in given double precision position
+ */
+inline v3s16 doubleToInt(v3d p, double d)
+{
+	return v3s16(
+		(p.X + (p.X > 0 ? d / 2 : -d / 2)) / d,
+		(p.Y + (p.Y > 0 ? d / 2 : -d / 2)) / d,
+		(p.Z + (p.Z > 0 ? d / 2 : -d / 2)) / d);
+}
+
 /*
 	Returns floating point position of node in given integer position
 */
-- 
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