From d6fe4c3bbd16b7511223b2bedb787da25c664b34 Mon Sep 17 00:00:00 2001
From: cx384 <cx384@proton.me>
Date: Thu, 11 Apr 2024 22:18:49 +0200
Subject: [PATCH] Make alignment behave like other elements

---
 builtin/game/hud.lua                |  2 +-
 doc/lua_api.md                      |  4 +---
 games/devtest/mods/testhud/init.lua | 10 ++++++----
 src/client/hud.cpp                  | 10 +++++-----
 src/client/hud.h                    |  2 +-
 src/script/common/c_content.cpp     |  5 ++++-
 6 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/builtin/game/hud.lua b/builtin/game/hud.lua
index cfd321fc2..d75eef813 100644
--- a/builtin/game/hud.lua
+++ b/builtin/game/hud.lua
@@ -267,7 +267,7 @@ register_builtin_hud_element("hotbar", {
 		type = "hotbar",
 		position = {x = 0.5, y = 1},
 		direction = 0,
-		alignment = {x = -0.5, y = -1},
+		alignment = {x = 0, y = -1},
 		offset = {x = 0, y = -4}, -- Extra padding below.
 	},
 	show_elem = function(player, flags)
diff --git a/doc/lua_api.md b/doc/lua_api.md
index d3185416a..1509b66ab 100644
--- a/doc/lua_api.md
+++ b/doc/lua_api.md
@@ -1751,15 +1751,13 @@ Displays a horizontal bar made up of half-images with an optional background.
 * `item`: Position of item that is selected.
 * `direction`: Direction the list will be displayed in
 * `offset`: offset in pixels from position.
-* `alignment`: The alignment of the inventory.
-  It starts at the top left corner and not at the center like most other types.
+* `alignment`: The alignment of the inventory. Aligned at the top left corner if not specified.
 
 ### `hotbar`
 
 * `direction`: Direction the list will be displayed in
 * `offset`: offset in pixels from position.
 * `alignment`: The alignment of the inventory.
-  It starts at the top left corner and not at the center like the most other types.
 
 ### `waypoint`
 
diff --git a/games/devtest/mods/testhud/init.lua b/games/devtest/mods/testhud/init.lua
index f5325932f..8c0cd9c89 100644
--- a/games/devtest/mods/testhud/init.lua
+++ b/games/devtest/mods/testhud/init.lua
@@ -213,25 +213,27 @@ local hud_hotbar_defs = {
 		type = "hotbar",
 		position = {x=0.2, y=0.5},
 		direction = 0,
-		alignment = {x=0, y=-1},
+		alignment = {x=1, y=-1},
 	},
 	{
 		type = "hotbar",
 		position = {x=0.2, y=0.5},
 		direction = 2,
+		alignment = {x=1, y=1},
 	},
 	{
 		type = "hotbar",
 		position = {x=0.7, y=0.5},
 		direction = 0,
-		offset = {x=40, y=20},
+		offset = {x=140, y=20},
+		alignment = {x=-1, y=-1},
 	},
 	{
 		type = "hotbar",
 		position = {x=0.7, y=0.5},
 		direction = 2,
-		alignment = {x=0, y=-1},
-		offset = {x=40, y=20},
+		offset = {x=140, y=20},
+		alignment = {x=-1, y=1},
 	},
 }
 
diff --git a/src/client/hud.cpp b/src/client/hud.cpp
index 91167e0ac..0b6cdb74a 100644
--- a/src/client/hud.cpp
+++ b/src/client/hud.cpp
@@ -236,7 +236,7 @@ void Hud::drawItem(const ItemStack &item, const core::rect<s32>& rect,
 
 // NOTE: selectitem = 0 -> no selected; selectitem is 1-based
 // mainlist can be NULL, but draw the frame anyway.
-void Hud::drawItems(v2s32 upperleftpos, v2s32 screen_offset, s32 itemcount, v2f alignment,
+void Hud::drawItems(v2s32 screen_pos, v2s32 screen_offset, s32 itemcount, v2f alignment,
 		s32 inv_offset, InventoryList *mainlist, u16 selectitem, u16 direction,
 		bool is_hotbar)
 {
@@ -249,11 +249,11 @@ void Hud::drawItems(v2s32 upperleftpos, v2s32 screen_offset, s32 itemcount, v2f
 		width = tmp;
 	}
 
-	// Position of upper left corner of bar
+	// Position: screen_pos + screen_offset + alignment
 	v2s32 pos(screen_offset.X * m_scale_factor, screen_offset.Y * m_scale_factor);
-	pos += upperleftpos;
-	pos.X += alignment.X * width;
-	pos.Y += alignment.Y * height;
+	pos += screen_pos;
+	pos.X += (alignment.X - 1.0f) * (width * 0.5f);
+	pos.Y += (alignment.Y - 1.0f) * (height * 0.5f);
 
 	// Store hotbar_image in member variable, used by drawItem()
 	if (hotbar_image != player->hotbar_image) {
diff --git a/src/client/hud.h b/src/client/hud.h
index d1191464d..6bccf0b13 100644
--- a/src/client/hud.h
+++ b/src/client/hud.h
@@ -100,7 +100,7 @@ private:
 			const std::string &texture, const std::string& bgtexture,
 			s32 count, s32 maxcount, v2s32 offset, v2s32 size = v2s32());
 
-	void drawItems(v2s32 upperleftpos, v2s32 screen_offset, s32 itemcount, v2f alignment,
+	void drawItems(v2s32 screen_pos, v2s32 screen_offset, s32 itemcount, v2f alignment,
 			s32 inv_offset, InventoryList *mainlist, u16 selectitem,
 			u16 direction, bool is_hotbar);
 
diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
index de4f2fe02..6f138d080 100644
--- a/src/script/common/c_content.cpp
+++ b/src/script/common/c_content.cpp
@@ -2303,7 +2303,10 @@ void read_hud_element(lua_State *L, HudElement *elem)
 		elem->dir = getintfield_default(L, 2, "dir", 0);
 
 	lua_getfield(L, 2, "alignment");
-	elem->align = lua_istable(L, -1) ? read_v2f(L, -1) : v2f();
+	if (lua_istable(L, -1))
+		elem->align = read_v2f(L, -1);
+	else
+		elem->align = elem->type == HUD_ELEM_INVENTORY ? v2f(1.0f, 1.0f) : v2f();
 	lua_pop(L, 1);
 
 	lua_getfield(L, 2, "offset");