minetest_modding_book/_de/players/hud.md

title	layout	root	idx	description	redirect_from
HUD	default	../..	4.6	Lernen Sie, wie man HUD-Elemente anzeigt	/de/chapters/hud.html

Introduction

Heads Up Display (HUD) Elemente ermöglichen es Ihnen, Text, Bilder und andere grafische Elemente anzuzeigen.

Das HUD akzeptiert keine Benutzereingaben; dafür sollten Sie eine formspec verwenden.

• Positionierung
  • Position und Versatz
  • Alignment
  • Scoreboard
• Text Elements
  • Parameters
  • Our Example
• Image Elements
  • Parameters
  • Scale
• Changing an Element
• Storing IDs
• Other Elements

Positionierung

Position und Versatz

Bildschirme gibt es in verschiedenen Größen und Auflösungen, und das HUD muss auf allen Bildschirmtypen gut funktionieren.

Die Lösung von Minetest besteht darin, die Position eines Elements sowohl durch einer prozentualen Position und einem Versatz. Die prozentuale Position bezieht sich auf die Bildschirmgröße, d. h. um ein Element in der Mitte des Bildschirms zu platzieren, müssen Sie eine prozentuale Position von der Hälfte des Bildschirms, z. B. (50%, 50%), und einen Versatz von (0, 0) angeben.

Der Versatz wird dann verwendet, um ein Element relativ zur Prozentposition zu verschieben.

Alignment

Die Ausrichtung gibt an, wo das Ergebnis von Position und Versatz auf dem Element liegt - zum Beispiel, {x = -1.0, y = 0.0} lässt das Ergebnis von Position und Versatz auf die linke Seite der Elementbegrenzung. Dies ist besonders nützlich, wenn Sie ein Textelement links-, mittel- oder rechtsbündig auszurichten.

Das obige Diagramm zeigt 3 Fenster (blau), jedes mit einem einzelnen HUD-Element (gelb) und jeweils einer anderen Ausrichtung. Der Pfeil ist das Ergebnis der Berechnung von Position und Versatzberechnung.

Scoreboard

For the purposes of this chapter, you will learn how to position and update a score panel like so:

In the above screenshot, all the elements have the same percentage position (100%, 50%) - but different offsets. This allows the whole thing to be anchored to the right of the window, but to resize without breaking.

Text Elements

You can create a HUD element once you have a copy of the player object:

local player = minetest.get_player_by_name("username")
local idx = player:hud_add({
     hud_elem_type = "text",
     position      = {x = 0.5, y = 0.5},
     offset        = {x = 0,   y = 0},
     text          = "Hello world!",
     alignment     = {x = 0, y = 0},  -- center aligned
     scale         = {x = 100, y = 100}, -- covered later
})

The hud_add function returns an element ID - this can be used later to modify or remove a HUD element.

Parameters

The element's type is given using the hud_elem_type property in the definition table. The meaning of other properties varies based on this type.

scale is the maximum bounds of text; text outside these bounds is cropped, e.g.: {x=100, y=100}.

number is the text's colour, and is in hexadecimal form, e.g.: 0xFF0000.

Our Example

Let's go ahead and place all the text in our score panel:

-- Get the dig and place count from storage, or default to 0
local meta        = player:get_meta()
local digs_text   = "Digs: " .. meta:get_int("score:digs")
local places_text = "Places: " .. meta:get_int("score:places")

player:hud_add({
    hud_elem_type = "text",
    position  = {x = 1, y = 0.5},
    offset    = {x = -120, y = -25},
    text      = "Stats",
    alignment = 0,
    scale     = { x = 100, y = 30},
    number    = 0xFFFFFF,
})

player:hud_add({
    hud_elem_type = "text",
    position  = {x = 1, y = 0.5},
    offset    = {x = -180, y = 0},
    text      = digs_text,
    alignment = -1,
    scale     = { x = 50, y = 10},
    number    = 0xFFFFFF,
})

player:hud_add({
    hud_elem_type = "text",
    position  = {x = 1, y = 0.5},
    offset    = {x = -70, y = 0},
    text      = places_text,
    alignment = -1,
    scale     = { x = 50, y = 10},
    number    = 0xFFFFFF,
})

This results in the following:

Image Elements

Image elements are created in a very similar way to text elements:

player:hud_add({
    hud_elem_type = "image",
    position  = {x = 1, y = 0.5},
    offset    = {x = -220, y = 0},
    text      = "score_background.png",
    scale     = { x = 1, y = 1},
    alignment = { x = 1, y = 0 },
})

You will now have this:

Parameters

The text field is used to provide the image name.

If a co-ordinate is positive, then it is a scale factor with 1 being the original image size, 2 being double the size, and so on. However, if a co-ordinate is negative, it is a percentage of the screen size. For example, x=-100 is 100% of the width.

Scale

Let's make the progress bar for our score panel as an example of scale:

local percent = tonumber(meta:get("score:score") or 0.2)

player:hud_add({
    hud_elem_type = "image",
    position  = {x = 1, y = 0.5},
    offset    = {x = -215, y = 23},
    text      = "score_bar_empty.png",
    scale     = { x = 1, y = 1},
    alignment = { x = 1, y = 0 },
})

player:hud_add({
    hud_elem_type = "image",
    position  = {x = 1, y = 0.5},
    offset    = {x = -215, y = 23},
    text      = "score_bar_full.png",
    scale     = { x = percent, y = 1},
    alignment = { x = 1, y = 0 },
})

We now have a HUD that looks like the one in the first post! There is one problem however, it won't update when the stats change.

Changing an Element

You can use the ID returned by the hud_add method to update it or remove it later.

local idx = player:hud_add({
     hud_elem_type = "text",
     text          = "Hello world!",
     -- parameters removed for brevity
})

player:hud_change(idx, "text", "New Text")
player:hud_remove(idx)

The hud_change method takes the element ID, the property to change, and the new value. The above call changes the text property from "Hello World" to "New text".

This means that doing the hud_change immediately after the hud_add is functionally equivalent to the following, in a rather inefficient way:

local idx = player:hud_add({
     hud_elem_type = "text",
     text          = "New Text",
})

Storing IDs

score = {}
local saved_huds = {}

function score.update_hud(player)
    local player_name = player:get_player_name()

    -- Get the dig and place count from storage, or default to 0
    local meta        = player:get_meta()
    local digs_text   = "Digs: " .. meta:get_int("score:digs")
    local places_text = "Places: " .. meta:get_int("score:places")
    local percent     = tonumber(meta:get("score:score") or 0.2)

    local ids = saved_huds[player_name]
    if ids then
        player:hud_change(ids["places"], "text", places_text)
        player:hud_change(ids["digs"],   "text", digs_text)
        player:hud_change(ids["bar_foreground"],
                "scale", { x = percent, y = 1 })
    else
        ids = {}
        saved_huds[player_name] = ids

        -- create HUD elements and set ids into `ids`
    end
end

minetest.register_on_joinplayer(score.update_hud)

minetest.register_on_leaveplayer(function(player)
    saved_huds[player:get_player_name()] = nil
end)

Other Elements

Read lua_api.txt for a complete list of HUD elements.