From 1237206d4bdf840ae89018d14a0510035d54d0d3 Mon Sep 17 00:00:00 2001
From: Loic Blot <loic.blot@unix-experience.fr>
Date: Sun, 25 Jun 2017 23:08:31 +0200
Subject: [PATCH] Revert "Ores: Make 'absheight' flag non-functional"

This reverts commit 90ed6fc732ca667ca970b7c38d39c809e5c3553e.
---
 doc/lua_api.txt |  7 ++++++-
 src/mg_ore.cpp  | 19 +++++++++++++++----
 src/mg_ore.h    |  5 ++++-
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 63d090eb..540bbe11 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -1076,7 +1076,12 @@ Ore attributes
 See section "Flag Specifier Format".
 
 Currently supported flags:
-`puff_cliffs`, `puff_additive_composition`.
+`absheight`, `puff_cliffs`, `puff_additive_composition`.
+
+### `absheight`
+Also produce this same ore between the height range of `-y_max` and `-y_min`.
+
+Useful for having ore in sky realms without having to duplicate ore entries.
 
 ### `puff_cliffs`
 If set, puff ore generation will not taper down large differences in displacement
diff --git a/src/mg_ore.cpp b/src/mg_ore.cpp
index 73af2e2e..f959ca9e 100644
--- a/src/mg_ore.cpp
+++ b/src/mg_ore.cpp
@@ -27,7 +27,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 FlagDesc flagdesc_ore[] = {
-	{"absheight",                 OREFLAG_ABSHEIGHT}, // Non-functional
+	{"absheight",                 OREFLAG_ABSHEIGHT},
 	{"puff_cliffs",               OREFLAG_PUFF_CLIFFS},
 	{"puff_additive_composition", OREFLAG_PUFF_ADDITIVE},
 	{NULL,                        0}
@@ -87,11 +87,22 @@ void Ore::resolveNodeNames()
 
 size_t Ore::placeOre(Mapgen *mg, u32 blockseed, v3s16 nmin, v3s16 nmax)
 {
-	if (!(nmin.Y <= y_max && nmax.Y >= y_min))
+	int in_range = 0;
+
+	in_range |= (nmin.Y <= y_max && nmax.Y >= y_min);
+	if (flags & OREFLAG_ABSHEIGHT)
+		in_range |= (nmin.Y >= -y_max && nmax.Y <= -y_min) << 1;
+	if (!in_range)
 		return 0;
 
-	int actual_ymin = MYMAX(nmin.Y, y_min);
-	int actual_ymax = MYMIN(nmax.Y, y_max);
+	int actual_ymin, actual_ymax;
+	if (in_range & ORE_RANGE_MIRROR) {
+		actual_ymin = MYMAX(nmin.Y, -y_max);
+		actual_ymax = MYMIN(nmax.Y, -y_min);
+	} else {
+		actual_ymin = MYMAX(nmin.Y, y_min);
+		actual_ymax = MYMIN(nmax.Y, y_max);
+	}
 	if (clust_size >= actual_ymax - actual_ymin + 1)
 		return 0;
 
diff --git a/src/mg_ore.h b/src/mg_ore.h
index 5aeb3631..4b052e07 100644
--- a/src/mg_ore.h
+++ b/src/mg_ore.h
@@ -32,11 +32,14 @@ class MMVManip;
 
 /////////////////// Ore generation flags
 
-#define OREFLAG_ABSHEIGHT     0x01 // Non-functional but kept to not break flags
+#define OREFLAG_ABSHEIGHT     0x01
 #define OREFLAG_PUFF_CLIFFS   0x02
 #define OREFLAG_PUFF_ADDITIVE 0x04
 #define OREFLAG_USE_NOISE     0x08
 
+#define ORE_RANGE_ACTUAL 1
+#define ORE_RANGE_MIRROR 2
+
 enum OreType {
 	ORE_SCATTER,
 	ORE_SHEET,