Freeze-frame

.luacheckrc

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+read_globals = {
+    "DIR_DELIM", "INIT",
+
+    "minetest", "core",
+    "dump", "dump2",
+
+    "Raycast",
+    "Settings",
+    "PseudoRandom",
+    "PerlinNoise",
+    "VoxelManip",
+    "SecureRandom",
+    "VoxelArea",
+    "PerlinNoiseMap",
+    "PcgRandom",
+    "ItemStack",
+    "AreaStore",
+
+    "vector",
+
+    table = {
+        fields = {
+            "copy",
+            "indexof",
+            "insert_all",
+            "key_value_swap",
+            "shuffle",
+        }
+    },
+
+    string = {
+        fields = {
+            "split",
+            "trim",
+        }
+    },
+
+    math = {
+        fields = {
+            "hypot",
+            "sign",
+            "factorial"
+        }
+    },
+}
+
+ignore = "513"

LICENSE.txt

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+MIT Copyright 2021 GreenXenith
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Animated Entity Textures
+Created as an exercise in entity and texture handling for a Discord challenge.  
+
+The `_tiles` key should be a table of [tiles](https://github.com/minetest/minetest/blob/5.4.1/doc/lua_api.txt#L7124-L7144). Animated tiles should use the [tile animation definition](https://github.com/minetest/minetest/blob/5.4.1/doc/lua_api.txt#L7146-L7173) (optional).  
+
+### Minimum Example
+```lua
+minetest.register_entity("modname:verticalframes", {
+    _tiles = {{
+        name = "vertical_frames.png",
+        animation = {type = "vertical_frames", aspect_w = 16, aspect_h = 16, length = 1}
+    }},
+})
+
+minetest.register_entity("modname:sheet2d", {
+    _tiles = {{
+        name = "sheet_2d.png",
+        animation = {type = "sheet_2d", frames_w = 4, frames_h = 2, frame_length = 0.25}
+    }},
+})
+```
+
+Set `TEST` to `true` in `init.lua` to register these testing entities.

init.lua

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+local TEST = false
+
+local function get_file_dimensions(path)
+    local f = io.open(path, "rb")
+    f:seek("set", 1)
+    if f:read(3) == "PNG" then
+        f:seek("set", 16)
+        return {
+            w = tonumber(string.format("0x%x%x%x%x", f:read(4):byte(1, 4))),
+            h = tonumber(string.format("0x%x%x%x%x", f:read(4):byte(1, 4))),
+        }
+    end
+end
+
+local function find_textures(path, files)
+    files = files or {}
+    for _, filename in pairs(minetest.get_dir_list(path, false)) do
+        if filename:sub(-4) == ".png" then
+            files[filename] = get_file_dimensions(path .. "/" .. filename)
+        end
+    end
+
+    for _, dir in pairs(minetest.get_dir_list(path, true)) do
+        files = find_textures(path .. "/" .. dir, files)
+    end
+
+    return files
+end
+
+-- List of dimensions for all textures
+local texturelist = {}
+for _, modname in pairs(minetest.get_modnames()) do
+    texturelist = find_textures(minetest.get_modpath(modname), texturelist)
+end
+
+local old_dynamic_add = minetest.dynamic_add_media
+minetest.dynamic_add_media = function(filepath, ...)
+    local success = old_dynamic_add(filepath, ...)
+    if success then texturelist[filepath:match("[^/\\]+$")] = get_file_dimensions(filepath) end
+    return success
+end
+
+-- Animation handler
+minetest.register_globalstep(function(dtime)
+    for _, ent in pairs(minetest.luaentities) do
+        -- _tiles and properties must exist
+        if ent._tiles and ent.object:get_properties() then
+            local textures = ent.object:get_properties().textures
+            local tiles = table.copy(ent._tiles)
+
+            for i, tile in pairs(tiles) do
+                if type(tile) == "table" then
+                    if tile.animation then
+                        local anim = tile.animation
+                        assert(anim.type and (anim.type == "vertical_frames" or anim.type == "sheet_2d"), ("Invalid animated tile type in entity '%s'."):format(ent.name))
+
+                        tiles[i]._timer = (tile._timer or 0) + dtime
+                        tiles[i]._frame = tile._frame or 0
+
+                        local size = texturelist[tile.name] or {w = 16, h = 16}
+
+                        if anim.type == "vertical_frames" then
+                            assert(anim.aspect_w and anim.aspect_h and anim.length, ("Invalid vertical_frames animation definition in entity '%s'."):format(ent.name))
+                            -- height / frame height (width / aspect ratio)
+                            local total_frames = size.h / (size.w * (anim.aspect_h / anim.aspect_w))
+
+                            -- floor(timer / seconds per frame)
+                            tile._frame = math.floor(tile._timer / (anim.length / total_frames)) % total_frames
+                            tile._timer = tile._timer % anim.length
+
+                            textures[i] = ("%s^[verticalframe:%s:%s"):format(tile.name, total_frames, tile._frame)
+                        else -- type == "sheet_2d"
+                            assert(anim.frames_w and anim.frames_h and anim.frame_length, ("Invalid sheet_2d animation definition in entity '%s'."):format(ent.name))
+                            local total_frames = anim.frames_w * anim.frames_h
+                            local tile_w, tile_h = size.w / anim.frames_w, size.h / anim.frames_h
+
+                            tile._frame = math.floor((tile._timer / anim.frame_length)) % total_frames
+                            tile._timer = tile._timer % (total_frames * anim.frame_length)
+
+                            textures[i] = ("[combine:%sx%s:%s,%s=%s"):format(tile_w, tile_h, -(tile._frame % anim.frames_w) * tile_h, -math.floor(tile._frame / anim.frames_w) * tile_w, tile.name)
+                        end
+                    else
+                        textures[i] = tile.name
+                    end
+                else
+                    textures[i] = tile
+                end
+            end
+
+            ent._tiles = tiles
+            ent.object:set_properties({textures = textures})
+        end
+    end
+end)
+
+-- Test
+if TEST then
+    local speed = 1
+    minetest.register_entity("entity_anim:verticalframes", {
+        _tiles = {{name = "entity_anim_test_verticalframes.png", animation = {type = "vertical_frames", aspect_w = 1, aspect_h = 1, length = speed}}}
+    })
+    
+    minetest.register_entity("entity_anim:sheet2d", {
+        _tiles = {{name = "entity_anim_test_sheet2d.png", animation = {type = "sheet_2d", frames_w = 2, frames_h = 2, frame_length = speed / 4}}}
+    })
+end

mod.conf

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+name = entity_anim
+description = Animated texture support for entities.