hump - LÖVE Helper Utilities for More Productivity

hump.gamestate^ top

require "hump.gamestate"

A gamestate encapsulates independant data an behaviour into a single entity.

A typical game could consist of a menu-state, a level-state and a game-over-state.

Module overview

new(): Create new gamestate.
switch(): Switch to gamestate.
update(): Manually update current gamestate.
draw(): Manually draw the current gamestate.
keypressed(): Inform current gamestate of keypressed event.
keyreleased(): Inform current gamestate of keyreleased event.
mousepressed(): Inform current gamestate of mousepressed event.
mousereleased(): Inform current gamestate of mousereleased event.
joystickpressed(): Inform current gamestate of joystickpressed event.
joystickreleased(): Inform current gamestate of a joystickreleased event.
registerEvents(): Automatically do all of the above when needed.

Gamestate Callbacks

A gamestate can define (nearly) all callbacks that LÖVE defines. In addition, there are callbacks for entering and leaving a state.:

enter(previous, ...): Called when entering the state. See switch().
leave(): Called when leaving a state. See switch().
update(): Update the game state. Called every frame.
draw(): Draw on the screen. Called every frame.
keypressed(): Triggered when a key is pressed.
keyreleased(): Triggered when a key is released.
mousepressed(): Triggered when a mouse button is pressed.
mousereleased(): Triggered when a mouse button is released.
joystickpressed(): Triggered when a joystick button is pressed.
joystickreleased(): Triggered when a joystick button is released.

When using registerEvents(), all these callbacks will receive the same arguments as the LÖVE callbacks do.

Example:

menu = Gamestate.new()
function menu:enter(previous, background_image)
    self.background = background_image
    Buttons.initialize()
end

function menu:leave()
    Buttons.cleanup()
end

function menu:update(dt)
    Buttons.update(dt)
end

function menu:draw()
    love.graphics.draw(self.background, 0, 0)
    Buttons.draw()
end

function menu:keyreleased(key)
    if key == 'up' then
        Buttons.selectPrevious()
    elseif key == 'down' then
        Buttons.selectNext()
    elseif
        Buttons.active:onClick()
    end
end

function menu:mousereleased(x,y, mouse_btn)
    local button = Buttons.hovered(x,y)
    if button then
        Button.select(button)
        if mouse_btn == 'l' then
            button:onClick()
        end
    end
end

function new()^ top

Declare a new gamestate. A gamestate can define several callbacks.

Parameters:

None

Returns:

Gamestate: The new gamestate.

Example:

menu = Gamestate.new()

function switch(to, ...)^ top

Switch to a gamestate, with any additional arguments passed to the new state.

Switching a gamestate will call the leave() callback on the current gamestate, replace the current gamestate with to and finally call enter(old_state, ...) on the new gamestate.

Parameters:

Gamestate to: Target gamestate.
mixed ...: Additional arguments to pass to to:enter().

Returns:

mixed: The result of to:enter().

Example:

Gamestate.switch(game, level_two)

function update(...)^ top

function draw(...)

function keypressed(...)

function keyreleased(...)

function mousepressed(...)

function mousereleased(...)

function joystickpressed(...)

function joystickreleased(...)

Calls the corresponding function on the current gamestate (see callbacks).

Only needed when not using registerEvents().

Parameters:

mixed ...: Arguments to pass to the corresponding callback.

Returns:

mixed: Result of the callback function.

Example:

function love.update(dt)
    Gamestate.update(dt)
end

function love.draw()
    local mx,my = love.mouse.getPosition()
    Gamestate.draw(mx, my)
end

function love.keypressed(key, code)
    Gamestate.keypressed(key, code)
end

function registerEvents()^ top

Parameters:

None

Returns:

Nothing

Example:

function love.load()
    Gamestate.registerEvents()
    Gamestate.switch(menu)
end

hump.timer^ top

require "hump.timer"

hump.timer provides a simple interface to use delayed functions, i.e. functions that will only be executed after some amount time.

In addition, the module offers facilities to create functions that interpolate or oscillate over time.

Module overview

add(): Add a timed function.
addPeriodic(): Add a periodic function.
clear(): Clear all timed and periodic functions.
update(): Update timers.
Interpolator(): Create a new interpolating function.
Oscillator(): Create a new oscillating function.

function add(delay, func)^ top

Add a timed function. The function will be executed when delay seconds have elapsed.

Note that there is no guarantee that the delay will be exceeded. It is, however, guaranteed that the function will not be executed before the delay has passed.

If the function is called, it will receive itself as only parameter. This may be useful to implement the periodic behavior of Timer.addPeriodic.

Parameters:

number delay: Time to pass before the function is called.
function func: The function to be called.

Returns:

Nothing

Example:

-- grant the player 5 seconds of immortality
player:setInvincible(true)
Timer.add(5, function() player:setInvincible(false) end)

-- print "foo" every second
Timer.add(1, function(func) print("foo") Timer.add(1, func) end)

function addPeriodic(delay, func, count)^ top

function addPeriodic(delay, func)

Add a periodic timed function, i.e. a function that will be called count times every delay seconds.

If count is omitted, the function loops until clear() is called.

Parameters:

number delay: Time to pass before the function is called.
function func: The function to be called.
number count: The number of times the function is called.

Returns:

Nothing

Example:

Timer.addPeriodic(1, function() lamp:toggleLight() end)

Timer.addPeriodic(0.3, function() mothership:spawnFighter() end, 5)

function clear()^ top

Clears all timers.

Parameters:

None

Returns:

Nothing

Example:

Timer.clear()

function update(dt)^ top

Update timers and execute functions if the deadline is reached. Use this in love.update().

Parameters:

number dt: Time that has passed since the last update().

Returns:

Nothing

Example:

function love.update(dt)
    do_stuff()
    Timer.update(dt)
end

function Interpolator(length, func)^ top

Create a wrapper for an interpolating function, i.e. a function that acts depending on how much time has passed.

The wrapper will have the prototype:

function wrapper(dt, ...)

dt is the time that has passed since the last call and ... are arguments passed to the interpolating function. It will return whatever the interpolating functions returns if the interpolation is not yet finished or nil if the interpolation is done.

The prototype of the interpolating function is:

function inter(fraction, ...)

where fraction is a number between 0 and 1 and ... are additional arguments supplied to the wrapper.

Parameters:

number length: Interpolation length in seconds.
function func: Interpolating function.

Returns:

function: The wrapper function.

Example:

fader = Interpolator(5, function(frac, r,g,b)
    love.graphics.setBackgroundColor(frac*r,frac*g,frac*b)
end)

function love.update(dt)
    fader(dt, 255,255,255)
end

function Oscillator(length, func)^ top

Create a wrapper for an oscillating function, which is basically a looping interpolating function.

The function prototypes are the same as with Interpolator():

function wrapper(dt, ...)

function oscillator(fraction, ...)

The wrapper function will return whatever oscillator() returns.

Parameters:

number length: Length of one interpolation period.
function func: Oscillating function.

Returns:

function: The wrapper function.

Example:

mover = Oscillator(10, function(frac)
   return 400 + 300 * math.sin(2*math.pi*frac)
end)

local xpos = 100
function love.update(dt)
    xpos = mover(dt)
end

function love.draw()
    love.graphics.circle('fill', xpos, 300, 80, 36)
end

hump.vector^ top

require "hump.vector"

A handy 2D vector class defining the most common things you do with vectors.

You can access the individual coordinates by using vec.x and vec.y.

Module overview

new(): Create new vector.
isvector(): Test if value is a vector.
vector:clone(): Copy a vector.
vector:unpack(): Extract coordinates.
vector:permul(): Per element multiplication.
vector:len(): Get lenght.
vector:len2(): Get squared length.
vector:dist(): Get distance to vector.
vector:normalized(): Get normalized vector
vector:normalize_inplace(): Normalize vector in-place.
vector:rotated(): Get rotated vector.
vector:rotate_inplace(): Rotate vector in-place.
vector:perpendicular(): Get perpendicular vector.
vector:projectOn(): Get projection onto another vector.
vector:cross(): Cross product of two vectors.

Arithmetic and relational operators

Vector arithmetic is implemented by using __add, __mul and other metamethods:

vector + vector = vector: Component wise sum.
vector - vector = vector: Component wise difference.
vector * vector = number: Dot product.
number * vector = vector: Vector scaling.
vector * number = vector: Vector scaling.
vector / number = vector: Vector scaling.

Relational operators are defined, too:

a == b: true, if a.x == b.x and a.y == b.y.
a <= b: true, if a.x <= b.x and a.y <= b.y.
a < b: Lexical sort: true, if a.x < b.x or a.x == b.x and a.y < b.y.

Example:

acceleration = vector(0,-9)
player.velocity = player.velocity + acceleration * dt
player.position = player.position + player.velocity * dt

function new(x,y)^ top

Create new vector

Parameters:

numbers x, y: Coordinates.

Returns:

vector: The vector.

Example:

a = vector.new(10,10)

As a shortcut, you can call the module like a function, i.e.:

vector = require 'hump.vector'
a = vector(10,10)

function isvector(v)^ top

Test whether a variable is a vector.

Parameters:

mixed v: The variable to test.

Returns:

boolean: true if v is a vector, false otherwise.

Example:

if not vector.isvector(v) then
    v = vector(v,0)
end

function vector:clone()^ top

Copy a vector. Simply assigning a vector a vector to a variable will create a reference, so when you modify the vector referenced by the new variable, will also change the old one:

a = vector(1,1) -- create vector
b = a           -- b references a
c = a:clone()   -- c is a copy of a
b.x = 0         -- changes a,b and c
print(a,b,c)    -- prints '(1,0), (1,0), (1,1)'

Parameters:

None

Returns:

vector: The copied vector.

Example:

copy = original:clone()

function vector:unpack()^ top

Extract coordinates.

Parameters:

None

Returns:

numbers: The coordinates.

Example:

x,y = pos:unpack()

love.graphics.draw(self.image, self.pos:unpack())

function vector:permul(other)^ top

Multiplies vectors coordinate wise, i.e. result = vector(a.x * b.x, a.y * b.y).

This does not change either argument vectors, but creates a new one.

Parameters:

vector other: The other vector.

Returns:

vector: New vector as defined above.

Example:

scaled = original:permul(vector(1,1.5))

function vector:len()^ top

Get length of a vector, i.e. math.sqrt(vec.x * vec.x + vec.y * vec.y).

Parameters:

None

Returns:

number: Length of the vector.

Example:

distance = (a - b):len()

function vector:len2()^ top

Get squared length of a vector, i.e. vec.x * vec.x + vec.y * vec.y.

Parameters:

None

Returns:

number: The squared length.

Example:

-- get closest vertex to a given vector
closest, dsq = vertices[1], (pos - vertices[1]):len2()
for i = 2,#vertices do
    local temp = (pos - vertices[i]):len2()
    if temp < dsq then
        closest, dsq = vertices[i], temp
    end
end

function vector:dist(other)^ top

Get distance of two vectors. The same as (a - b):len().

Parameters:

vector other: Other vector to measure the distance.

Returns:

number: The distance of both vectors.

Example:

-- get closest vertex to a given vector
-- slightly slower than the example using len2()
closest, dist = vertices[1], pos:dist(vertices[1])
for i = 2,#vertices do
    local temp = pos:dist(vertices[i])
    if temp < dist then
        closest, dist = vertices[i], temp
    end
end

function vector:normalized()^ top

Get normalized vector, i.e. a vector with the same direction as the input vector, but length 1.

This does not change the input vector, but creates a new vector.

Parameters:

None

Returns:

vector: Vector with same direction as the input vector, but length 1.

Example:

normal = edge:normalized()

function vector:normalize_inplace()^ top

Normalize a vector, i.e. make the vector unit length.

This modifies the vector. If in doubt, use vector:normalized().

Parameters:

None

Returns:

vector: The normalized vector.

Example:

normal = (b - a):perpendicular():normalize_inplace()

function vector:rotated(phi)^ top

Get a rotated vector.

This does not change the input vector, but creates a new vector.

Parameters:

number phi: Rotation angle in radians.

Returns:

vector: The rotated vector.

Example:

-- approximate a circle
circle = {}
for i = 1,30 do
    local phi = 2 * math.pi * i / 30
    circle[#circle+1] = vector(0,1):rotated(phi)
end

Sketch:

sketch of rotated vectors

function vector:rotate_inplace(phi)^ top

Rotate a vector.

This modifies the vector. If in doubt, use vector:rotate().

Parameters:

number phi: Rotation angle in radians.

Returns:

vector: The rotated vector.

Example:

spawner.angle = spawner.angle + dt
spawner.direction:rotate_inplace(spawner.angle)

function vector:perpendicular()^ top

Quick rotation by 90°. Creates a new vector. The same as (but faster):

vec:rotate(math.pi/2)

Parameters:

None

Returns:

vector: A vector perpendicular on the input vector.

Example:

normal = (b - a):perpendicular():normalize_inplace()

Sketch:

sketch of perpendicular vectors

function vector:projectOn(v)^ top

Project vector onto another vector.

Parameters:

vector v: The vector to project on.

Returns:

vector: The projected vector.

Example:

velocity_component = velocity:projectOn(axis)

Sketch:

sketch of vector projection

function vector:cross(other)^ top

Get cross product of both vectors.

For the math geeks:

The cross product not be defined for 2D vectors. To nonetheless get a result, treat the vectors as being 3D vectors (x,y,0). The cross product of both vectors has just a z-component, and this is what this function returns. It's also the determinant of both vectors: d = det(a,b).

Parameters:

vector other: Vector to compute the cross product with.

Returns:

number: The cross product of both vectors.

Example:

parallelogram_are = a:cross(b)

hump.class^ top

require "hump.class"

A small, handy class implementation with multiple inheritance.

Module overview

new(): Create new class.
class.construct(): Call class constructor.
inherit(): Class inheritance.

function new(constructor)^ top

function new{name = the_name, constructor}

Define a new class.

The constructor will receive the newly created object as first argument.

If you required the module to a variable, you can use the variable as a shortcut to new().

Parameters:

function constructor: Class constructor.
string the_name: Class name to be returned when calling tostring() on the class.

Returns:

Class: The class.

Example:

Class = require 'hump.class'

-- define unnamed class
Feline = Class(function(self, size, weight)
    self.size = size
    self.weight = weight
end)

-- define class method
function Feline:stats()
    return string.format("size: %.02f, weight %.02f", self.size, self.weight)
end

-- create two objects
garfield = Feline(.7, 45)
felix = Feline(.8, 12)

print("Garfield: " .. garfield:stats(), "Felix: " .. felix:stats())

Class = require 'hump.class'

-- define named class
Feline = Class{name = "Feline", function(self, size, weight)
    self.size = size
    self.weight = weight
end}

garfield = Feline(.7, 45)
print(Feline, garfield) -- prints 'Feline	<instance of Feline>'

function class.construct(object, ...)^ top

function class.Construct(object, ...)

Calls class constructor of a class.

Needed in constructors of child classes to initialize parts of the object that the parent classes define.

Parameters:

Object object: The object. This is usually self.
mixed ...: Arguments to pass to the constructor.

Returns:

Nothing

Example:

Class = require 'hump.class'

Feline = Class{name = "Feline", function(self, size, weight)
    self.size = size
    self.weight = weight
end}

Cat = Class{name = "Cat", function(self, name, size, weight)
    Feline.construct(self, size, weight)
    self.name = name
end}
Cat:inherit(Feline)

function inherit(class, super, ...)^ top

function class:inherit(super, ...)

function class:Inherit(super, ...)

Inherit functions (but not class variables).

If multiple super-classes are defined inherit from all of these. If two super-classes define a method of the same name, inherit it from the one mentioned first.

Parameters:

Class class: Child class.
Classes super, ...: Parent classes to inherit from.

Returns:

Nothing

Example:

Class = require 'hump.class'

Feline = Class{name = "Feline", function(self, size, weight)
    self.size = size
    self.weight = weight
end}

function Feline:stats()
    return string.format("size: %.02f, weight %.02f", self.size, self.weight)
end

function Feline:speak() print("meow") end

Cat = Class{name = "Cat", function(self, name, size, weight)
    Feline.construct(self, size, weight)
    self.name = name
end}
Cat:inherit(Feline)

function Cat:stats()
    return string.format("name: %s, %s", self.name, Feline.stats(self))
end

Tiger = Class{name = "Tiger", function(self, size, weight)
    Feline.construct(self, size, weight)
end}
Tiger:Inherit(Feline)

function Tiger:speak() print("ROAR!") end

felix = Cat("Felix", .8, 12)
hobbes = Tiger(2.2, 68)

print(felix:stats())   -- "name: Felix, size: 0.80, weight 12.00"
print(hobbes:stats())  -- "size: 2.20, weight 68.00"
felix:speak()          -- "meow"
hobbes:speak()         -- "ROAR!"

Caveats

Be careful when using metamethods like __add or __mul: When subclass inherits those methods from a superclass, but does not overwrite them, the result of the operation may be of the type superclass. Consider the following:

Class = require 'hump.class'

A = Class(function(self, x) self.x = x end)
function A:__add(other) return A(self.x + other.x) end
function A:show() print("A:", self.x) end

B = Class(function(self, x, y) A.construct(self, x) self.y = y end)
B:Inherit(A)
function B:show() print("B:", self.x, self.y) end
function B:foo() print("foo") end

one, two = B(1,2), B(3,4)
result = one + two
result:show()   -- prints "A:    4"
result:foo()    -- error: method does not exist

hump.camera^ top

require "hump.camera"

Depends on vector

Camera abstraction for LÖVE. A camera "looks" at a position, can be moved, zoomed and rotated.

A camera defines it's own coordinate system, meaning that an object shown on the screen likely has different coordinates in the game world than it has on the screen.

For example, the mouse position could be 400,400, but since the camera looks at the point 100,100 and is rotated by 90°, the world coordinates are 200,100.

The camera class defines methods to convert between both coordinate systems.

Module overview

new(): Create new camera object.
camera:rotate(): Rotate camera.
camera:translate(): Move camera.
camera:predraw(): Apply camera transformation.
camera:postdraw(): Revert camera transformation.
camera:draw(): Apply camera transformations to a function.
camera:toCameraCoords(): Convert vector to camera coordinates.
camera:toWorldCoords(): Convert vector to world coordinates.
camera:mousepos(): Get mouse position in world coordinates.

function new(pos, zoom, rot)^ top

Create new camera object.

You can access and modify the camera parameters using camera.pos, camera.zoom and camera.rot.

Parameters:

vector pos (screen center): Position the camera should look at.
number zoom (1): Camera zoom.
number rot (0): Camera rotation in radians.

Returns:

camera: Camera object.

Example:

cam = hump.camera.new(vector(400,300), 2)

If you assigned the module to a variable, you can call the module as a shortcut to hump.camera.new():

camera = require 'hump.camera'
vector = require 'hump.vector'

cam = camera(vector(400,300), 2)

function camera:rotate(phi)^ top

Rotate the camera. Same as cam.rot = cam.rot + phi.

Parameters:

number phi: Rotation angle in radians.

Returns:

Nothing

Example:

cam:rotate(dt)

function camera:translate(direction)^ top

Move the camera. Same as cam.pos = cam.pos + direction

Parameters:

vector direction: Direction to move the camera.

Returns:

Nothing

Example:

cam:translate(vector(100,0) * dt)

function camera:predraw()^ top

Apply camera transformations, i.e. move, scale and rotate everything so that you see what you would see when looking through the camera.

Everything until the next camera:postdraw() will be transformed.

Parameters:

None

Returns:

Nothing

Example:

function love.draw()
    cam:predraw()
    draw_world()
    cam:postdraw()
    draw_hud()
end

function camera:postdraw()^ top

Revert camera transformations done by camera:predraw().

Parameters:

None

Returns:

Nothing

Example:

function love.draw()
    cam:predraw()
    draw_world()
    cam:postdraw()
    draw_hud()
end

function camera:draw(func)^ top

Wrap a function between predraw() and postdraw():

cam:predraw()
func()
cam:postdraw()

Parameters:

function func: Drawing function to be wrapped.

Returns:

Nothing

Example:

function love.draw()
    cam:draw( draw_world )
    draw_hud()
end

function camera:toCameraCoords(pos)^ top

Convert world coordinates to camera coordinates.

Parameters:

vector pos: Position in world coordinates.

Returns:

vector: Position in camera coordinates.

Example:

screen_coords = cam:toCameraCoords( player.pos )
love.graphics.line(love.mouse.getX(), love.mouse.getY(), screen_coords:unpack()

function camera:toWorldCoords(pos)^ top

Convert camera coordinates to world coordinates.

Parameters:

vector pos: Position in camera coordinates.

Returns:

vector: Position in world coordinates.

Example:

target = cam:toWorldCoords( vector(love.mouse.getPosition()) )
unit:plotPathTo(target)

function camera:mousepos()^ top

Get mouse position in world coordinates.

Parameters:

None

Returns:

vector: Mouse position in world coordinates.

Example:

target = cam:mousepos()
unit:plotPathTo(target)

hump.ringbuffer^ top

require "hump.ringbuffer"

A ring-buffer is a circular array. That means it does not have a first nor a last element.

You can use this to implement Tomb Raider style inventories, looping playlists, recurring dialogs (like a unit's answers when selecting it multiple times in Warcraft) and generally everything that has a circular or looping structure.

Module overview

new(): Create new ring-buffer.
ringbuffer:insert(): Insert element.
ringbuffer:remove(): Remove currently selected item.
ringbuffer:removeAt(): Remove an item.
ringbuffer:next(): Select next item.
ringbuffer:prev(): Select previous item.
ringbuffer:get(): Get currently selected item.
ringbuffer:size(): Get ringbuffer size.

function new(...)^ top

Create new ringbuffer.

Parameters:

mixed ...: Initial elements.

Returns:

Ringbuffer: Ringbuffer object.

Example:

rb = hump.ringbuffer.new(1,2,3)

As with vector, camera and class, you can call the module as shortcut to new():

ringbuffer = require 'hump.ringbuffer'

rb = ringbuffer(1,2,3)

function ringbuffer:insert(item, ...)^ top

Insert items behind current element.

Parameters:

mixed item, ...: Items to insert.

Returns:

Nothing

Example:

rb = ringbuffer(1,5,6) -- content: 1,5,6
rb:insert(2,3,4)       -- content: 1,2,3,4,5,6

function ringbuffer:remove()^ top

Remove currently selected item and select next item.

Parameters:

None

Returns:

mixed: The item removed.

Example:

rb = ringbuffer(1,2,3,4) -- content: 1,2,3,4
rb:next()                -- content: 2,3,4,1
rb:remove()              -- content: 3,4,1

function ringbuffer:removeAt(pos)^ top

Remove item at position relative to current item.

Parameters:

number pos: Position to remove.

Returns:

mixed: The item removed.

Example:

rb = ringbuffer(1,2,3,4,5) -- content: 1,2,3,4,5
rb:removeAt(2)             -- content: 1,2,4,5
rb:removeAt(-1)            -- content: 1,2,4

function ringbuffer:next()^ top

Select and return next item.

Parameters:

None

Returns:

mixed: The next item.

Example:

rb = ringbuffer(1,2,3)
print(rb:next()) -- prints '2'
print(rb:next()) -- prints '3'
print(rb:next()) -- prints '1'

function ringbuffer:prev()^ top

Select and return previous item.

Parameters:

None

Returns:

mixed: The previous item

Example:

rb = ringbuffer(1,2,3)
print(rb:prev()) -- prints '3'
print(rb:prev()) -- prints '2'
print(rb:prev()) -- prints '1'

function ringbuffer:get()^ top

Get currently selected item.

Parameters:

None

Returns:

mixed: Currently selected item.

Example:

rb = ringbuffer(1,2,3)
rb:next()
print(rb:get()) -- prints '2'

function ringbuffer:size()^ top

Get number of items in the buffer.

Parameters:

None

Returns:

number: Number of items in the buffer.

Example:

rb = ringbuffer(1,2,3)
print(rb:size()) -- prints '3'
rb:remove()
print(rb:size()) -- prints '2'

hump Helper Utilities for More Productivity

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Module overview

Gamestate Callbacks

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Caveats

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Module overview