90 lines
2.4 KiB
Lua
90 lines
2.4 KiB
Lua
local Object = require "lib/classic"
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---@alias AnimationFinishBehavior
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---| '"loop"' Loop the animation over from the beginning.
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---| '"stop"' Freeze the animation on the last frame.
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---| '"goto"' Go to another state.
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---@class State
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---@field animation Animation The animation frames for this state.
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---@field on_finish? AnimationFinishBehavior What to do after this state's animation finishes. Defaults to "loop".
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---@field next? string The next state to go to in the case of "goto" on_finish.
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local Animator = Object:extend()
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---Creates a new animator.
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---@param states { [string]: State } A dictionary of all states in this animator.
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---@param first_state string The first state of this animator.
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function Animator:new(states, first_state)
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---The states in this animator.
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self.states = states
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---The current state.
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self.state = first_state
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---The timestep of the current frame.
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self.step = 0
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---The current frame in the current animation.
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self.frame = 1
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--- The next state to progress to.
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self.next_state = nil
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end
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function Animator:update(dt)
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local state = self.states[self.state]
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local frames = state.animation.frames
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--Step the current timestep and return if the frame hasn't changed.
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self.step = self.step + dt
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if self.step <= frames[self.frame].duration then
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return
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end
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--Step the current frame and return if there are more.
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self.step = 0
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self.frame = self.frame + 1
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if self.frame <= #frames then
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return
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end
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--We've reached the end of the current state.
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if self.next_state then
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self.state = self.next_state
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self.frame = 1
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self.next_state = nil
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elseif state.on_finish == "goto" then
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self.state = state.next
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self.frame = 1
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elseif state.on_finish == "stop" then
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self.frame = #frames
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elseif state.on_finish == "loop" or state.on_finish == nil then
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self.frame = 1
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else
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error("Invalid state on_finish " .. state.on_finish)
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end
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end
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function Animator:draw(x, y)
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local state = self.states[self.state]
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state.animation:draw(self.frame, x, y)
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end
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---Sets the state of this animator.
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---@param state string The name of the state to set.
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---@param queue? boolean If true, queues the state change for after the current state.
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function Animator:setState(state, queue)
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if not self.states[state] then
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error("Invalid state " .. state)
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elseif queue then
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self.next_state = state
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else
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self.state = state
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self.step = 0
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self.frame = 1
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end
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end
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return Animator
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