174 lines
9.1 KiB
Markdown
174 lines
9.1 KiB
Markdown
API documentation for the HUD bars mod 1.0.0
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============================================
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## Introduction
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This API allows you to add, change, hide and unhide custom HUD bars for this mod.
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## Overview
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To give you a *very* brief overview over this API, here is the basic workflow on how to add your own custom HUD bar:
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* Create images for your HUD bar
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* Call `hb.register_hudbar` to make the definition of the HUD bar known to this mod
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* Call `hb.init_hudbar` for each player for which you want to use previously defined HUD bar
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* Use `hb.change_hudbar` whenever you need to change the values of a HUD bar of a certain player
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* If you need it: Use `hb.hide_hudbar` and `hb.unhide_hudbar` to hide or unhide HUD bars of a certain player
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## The basic rules
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In order to use this API, you should be aware of a few basic rules in order to understand it:
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* A HUD bar is an approximate graphical representation of the ratio of a current value and a maximum value, i.e. current health of 15 and maximum health of 20. A full HUD bar represents 100%, an empty HUD bar represents 0%.
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* The current value must always be equal to or smaller then the maximum
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* Both current value and maximum must not be smaller than 0
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* Both current value and maximum must be real numbers. So no NaN, infinity, etc.
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* The HUD bar will be hidden if the maximum equals 0. This is intentional.
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* The health and breath HUD bars are hardcoded.
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These are soft rules, the HUD bars mod will not enforce all of these.
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But this mod has been programmed under the assumption that these rules are followed, for integrity.
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## Adding a HUD bar
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To make a new HUD bar known to this mod, you need …
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* … an image of size 2×16 for the bar
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* … an icon of size 16×16 (optional)
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* … to register it with `hb.register_hudbar`
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### Bar image
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The image for the bar will be repeated horizontally to denote the “value” of the HUD bar.
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It **must** be of size 2×16.
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If neccessary, the image will be split vertically in half, and only the left half of the image
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is displayed. So the final HUD bar will always be displayed on a per-pixel basis.
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The default bar images are single-colored, but you can use other styles as well, for instance,
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a vertical gradient.
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### Icon
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A 16×16 image shown left of the HUD bar. This is optional.
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### `hb.register_hudbar(identifier, text_color, label, textures, default_start_value, default_start_max, default_start_hidden, format_string)`
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This function registers a new custom HUD bar definition to the HUD bars mod, so it can be later used to be displayed, changed, hidden
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and unhidden on a per-player basis.
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Note this does not yet display the HUD bar.
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The HUD bars will be displayed in a “first come, first serve” order. This mod does not allow fow a custom order or a way to set it
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manually in a reliable way.
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#### Parameters
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* `identifier`: A globally unique internal name for the HUD bar, will be used later to refer to it. Please only rely on alphanumeric characters for now. The identifiers “`health`” and “`breath`” are used internally for the built-in health and breath bar, respectively. Please do not use these names.
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* `text_color`: A 3-octet number defining the color of the text. The octets denote, in this order red, green and blue and range from `0x00` (complete lack of this component) to `0xFF` (full intensity of this component). Example: `0xFFFFFF` for white.
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* `label`: A string which is displayed on the HUD bar itself to describe the HUD bar. Try to keep this string short.
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* `textures`: A table with the following fields:
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* `bar`: The file name of the bar image (as string).
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* `icon`: The file name of the icon, as string. This field can be `nil`, in which case no icon will be used.
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* `default_start_value`: If this HUD bar is added to a player, and no initial value is specified, this value will be used as initial current value
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* `default_max_value`: If this HUD bar is added to a player, and no initial maximum value is specified, this value will be used as initial maximum value
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* `default_start_hidden`: The HUD bar will be initially start hidden by default when added to a player. Use `hb.unhide_hudbar` to unhide it.
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* `format_string`: This is optional; You can specify an alternative format string display the final text on the HUD bar. The default format string is “`%s: %d/%d`” (in this order: Label, current value, maximum value). See also the Lua documentation of `string.format`.
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#### Return value
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Always `nil`.
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## Displaying a HUD bar
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After a HUD bar has been registered, they are not yet displayed yet for any player. HUD bars must be
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explicitly initialized on a per-player basis.
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You probably want to do this in the `minetest.register_on_joinplayer`.
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### `hb.init_hudbar(player, identifier, start_value, start_max, start_hidden)`
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This function initialzes and activates a previously registered HUD bar and assigns it to a
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certain client/player. This has only to be done once per player and after that, you can change
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the values using `hb.change_hudbar`.
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However, if `start_hidden` was set to `true` for the HUD bar (in `hb.register_hudbar`), the HUD bar
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will initially be hidden, but the HUD elements are still sent to the client. Otherwise,
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the HUD bar will be initially be shown to the player.
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#### Parameters
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* `player`: `ObjectRef` of the player to which the new HUD bar should be displayed to.
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* `identifier`: The identifier of the HUD bar type, as specified in `hb.register_hudbar`.
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* `start_value`: The initial current value of the HUD bar. This is optional, `default_start_value` of the registration function will be used, if this is `nil`.
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* `start_max`: The initial maximum value of the HUD bar. This is optional, `default_start_max` of the registration function will be used, if this is `nil`
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* `start_hidden`: Whether the HUD bar is initially hidden. This is optional, `default_start_hidden` of the registration function will be used as default
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#### Return value
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Always `nil`.
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## Modifying a HUD bar
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After a HUD bar has been added, you can change the current and maximum value on a per-player basis.
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You use the function `hb.change_hudbar` for this.
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### `hb.change_hudbar(player, identifier, new_value, new_max_value)`
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Changes the values of an initialized HUD bar for a certain player. `new_value` and `new_max_value`
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can be `nil`; if one of them is `nil`, that means the value is unchanged. If both values
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are `nil`, this function is a no-op.
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This function also tries minimize the amount of calls to `hud_change` of the Minetest Lua API, and
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therefore, network traffic. `hud_change` is only called if it is actually needed, i.e. when the
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actual length of the bar or the displayed string changed, so you do not have to worry about it.
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#### Parameters
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* `player`: `ObjectRef` of the player to which the HUD bar belongs to
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* `identifier`: The identifier of the HUD bar type to change, as specified in `hb.register_hudbar`.
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* `new_value`: The new current value of the HUD bar
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* `new_max_value`: The new maximum value of the HUD bar
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#### Return value
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Always `nil`.
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## Hiding and unhiding a HUD bar
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You can also hide custom HUD bars, meaning they will not be displayed for a certain player. You can still
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use `hb.change_hudbar` on a hidden HUD bar, the new values will be correctly displayed after the HUD bar
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has been unhidden. Both functions will only call `hud_change` if there has been an actual change to avoid
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unneccessary traffic.
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Note that the hidden state of a HUD bar will *not* be saved by this mod on server shutdown, so you may need
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to write your own routines for this or by setting the correct value for `start_hidden` when calling
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`hb.init_hudbar`.
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### `hb.hide_hudbar(player, identifier)`
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Hides the specified HUD bar from the screen of the specified player.
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#### Parameters
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* `player`: `ObjectRef` of the player to which the HUD bar belongs to
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* `identifier`: The identifier of the HUD bar type to hide, as specified in `hb.register_hudbar`.
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#### Return value
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Always `nil`.
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### `hb.unhide_hudbar(player, identifier)`
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Makes a previously hidden HUD bar visible again to a player.
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#### Parameters
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* `player`: `ObjectRef` of the player to which the HUD bar belongs to
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* `identifier`: The identifier of the HUD bar type to unhide, as specified in `hb.register_hudbar`.
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#### Return value
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Always `nil`.
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## Reading HUD bar information
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It is also possible to read information about an active HUD bar.
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### `hb.get_hudbar_state(player, identifier)`
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Returns the current state of the active player's HUD bar.
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#### Parameters
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* `player`: `ObjectRef` of the player to which the HUD bar belongs to
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* `identifier`: The identifier of the HUD bar type to hide, as specified in `hb.register_hudbar`.
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#### Return value
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A table which holds information on the current state of the HUD bar. Note the table is a deep
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copy of the internal HUD bar state, it is *not* a reference; the information hold by the table is
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only true for the moment you called this function. The fields of this table are:
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* `value`: Current value of HUD bar.
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* `max`: Current maximum value of HUD bar.
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* `hidden`: Boolean denoting whether the HUD bar is hidden.
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* `barlength`: The length of the HUD bar in pixels. This field is meaningless if the HUD bar is currently hidden.
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* `text`: The text shown on the HUD bar. This fiels is meaningless if the HUD bar is currently hidden.
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