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hump Helper Utilities for More Productivity

Introduction^ top

Helper Utilities for a Multitude of Problems is a set of lightweight helpers for the excellent LÖVE Engine.

It currently features

hump differs from other libraries in that every component is independent of the remaining ones (apart from camera.lua, which depends on the vector type). hump's footprint is very small and thus should fit nicely into your projects.

Documentation^ top

Below is the documentation of the various modules. You can directly jump to a module by clicking these:

vector.lua^ top

A vector class implementing everything you want to do with vectors, and some more.

Overview (click item for more details):

vector(x,y)constructor
isvector(v)type check
Vector:clone()deep copy
Vector:unpack()element unfolding
OperatorsArithmetics and ordering
vector:permul(other)per-element multiplication
vector:len()vector length
vector:len2()squared vector length
vector:dist(other)distance to vector
vector:normalized()normalize vector
vector:normalize_inplace()normalize vector in-place
Vector:rotated(phi)rotate vector
Vector:rotate_inplace(phi)rotate vector in-place

function vector(x,y)^ top Creates a new vector. Element access with v.x and v.y.
Parameters:[number]x:x coordinate
[number]y:y coordinate
Returns:the vector
function isvector(v)^ top Tests for vector type.
Parameters:vvariable to test
Returns:true if v is a vector
function vector:clone()^ top Clones a vector. Use when you do not want to create references.
Returns:New vector with the same coordinates.
function vector:unpack()^ top Unpacks the vector.
Returns:the coordinate tuple x, y
Example:
v = vector(1,2)
print(v:unpack()) -- prints "1     2"
Operators^ top

Arithmetic (+, -, *, /) and comparative operators (==, <=, <) are defined:

  • + and - only work on vectors. - is also the unary minus (e.g. print(-vector(1,2)) -- prints (-1,-2))
  • a * b works on vectors and numbers:
    • If a is a number and b is a vector (or vice versa), the result the scalar multiplication.
    • If a and b both are vectors, then the result is the dot product.
  • a / b is only defined for a being a vector and b being a number. Same as a * 1/b.

<= and < sort lexically, i.e. a < b is true if it holds: a.x < b.x or a.y < b.y if a.x == b.x

function vector:permul(other)^ top Perform element-wise multiplication.
function vector:len()^ top Get length of vector.
function vector:len2()^ top Get squared length.
function vector:dist(other)^ top Get distance to other vector.
Example:
a,b = vector(0,1), vector(1,0)
print(a:dist(b)) -- prints 1.4142135623731
function vector:normalized()^ top Get normalized vector. The original vector remains unchanged.
function vector:normalize_inplace()^ top Normalize vector and return it.

Warning: This will change the state of all references to this vector.

function vector:rotated(phi)^ top Get rotated vector. The original vector remains unchanged.
Parameters:[number]phi:Rotation angle in radians.
function vector:rotate_inplace(phi)^ top Rotate the vector and return it.

Warning: This will change the state of all references to this vector.

class.lua^ top

class.lua provides a simple and easy to use class system. Albeit it's limitations, class.lua offers multiple inheritance and minimal reflection capabilities. Note that only methods will be inherited and runtime changes of a superclass won't affect subclasses.

The module only consists of three functions:

Class(constructor)define class
Class{name = name, constructor}define named class
Interface(name)define interface
Inherit(class, super, ...)subclassing

For an example, see below. Also be sure to read the warning regarding metamethods.

function Class(constructor)^ top Creates a new unnamed class.
Parameters:[optional function]constructor A function used to construct the class. The first parameter of this function is the object, the others are parameters given upon construction.
Returns:the new class
Example
Feline = Class(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

garfield = Feline(.7, 45)
felix = Feline(.8, 12)

print("Garfield: " .. garfield:stats(), "Felix: " .. felix:stats())
function Class{name = name, constructor}^ top Create a named class, i.e. define a __tostring metamethod. Parameters are the same as above. Great for debugging. Both name and constructor can be omitted (but why would you want to?)
Example:
Feline = Class{name = "Feline", function(self, size, weight)
self.size = size self.weight = weight
end}

print(Feline) -- prints 'Feline'
function Interface(name)^ top Shortcut to Class{name = name}, i.e. a possibly named class without constructor.
function Inherit(class, super, ...)^ top Add functions of super to class. Multiple interfaces can be defined.

super's constructor can be accessed via super.construct(self). See example below.

Example usage

Everybody loves cats!^ top
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}
Inherit(Cat, 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}
Inherit(Tiger, Feline)

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

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

print(felix:stats(), hobbes:stats())
felix:speak()
hobbes:speak()

Warning

Nothing is perfect^ top

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:

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

B = Class(function(self, x, y) A.construct(self, x) self.y = y end)
Inherit(B, A)
function B:print() 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:print()  -- prints "A:    4"
result:foo()    -- error: method does not exist

camera.lua^ top

Depends on vector.lua

Camera object to display only a partial region of the game world. The region can be zoomed and rotated. You can transform camera coordinates to world coordinated (e.g. get the location of the mouse in the game world). It is possible to have more than one camera per game.

The module defined the following funtions:

Camera(pos, zoom, rotation)create new camera
camera:rotate(phi)rotate camera
camera:translate(t)move camera
camera:draw(func)apply camera transformations on function
camera:apply()apply camera transformations
camera:deapply()revert camera transformations
camera:transform(p)get world coordinates
camera:mousepos()get world coordinates of mouse

function Camera(pos, zoom, rotation)^ top Create a new camera with position pos, zoom zoom and rotation rotation. Parameters:
Parameters:[optional vector]pos: Initial position of the camera. Defaults to (0,0).
[optional number]zoom: Initial zoom. Defaults to 1.
[optional number]rotation: Initial rotation in radians. Defaults to 0.
Returns:a new camera object
function camera:rotate(phi)^ top Rotate camera by phi radians. Same as camera.rot = camera.rot + phi.
function camera:translate(t)^ top Translate (move) camera by vector t. Same as camera.pos = camera.pos + t.
function camera:draw(func)^ top Apply camera transformation to drawings in function func. Shortcut to camera:apply() and camera:deapply() (see below).
Example
cam:draw(function() love.graphics.rectangle('fill', -100,-100, 200,200) end)
function camera:apply()^ top Apply camera transformations to every drawing operation until the next camera:deapply().
function camera:deapply()^ top Revert camera transformations for the rest of the drawing operations.
Example:(equivalent to the cam:draw() example above)
camera:apply()
love.graphics.rectangle('fill', -100,-100, 200,200)
camera:deapply()
function camera:transform(p)^ top Transform vector p from camera coordinates to world coordinates. You probably won't need this, but it is the basis to camera:mousepos().
function camera:mousepos()^ top Get mouse position in world coordinates, i.e. the position the users mouse is currently pointing at when camera transformations are applied. Use this for any mouse interaction with transformed objects in your game.

gamestate.lua^ top

Useful to separate different states of your game (hence "gamestate") like title screens, level loading, main game, etc. Each gamestate can have it's own update(), draw(), keyreleased(), keypressed() and mousereleased() which correspond to the ones defined in love. See the callback list for more details.

Additionally, each gamestate can define a enter(pre, ...) and leave() function, which are called when using Gamestate.switch(to, ...). Do not attempt to use these functions yourself to initialize the first gamestate, use the switch function instead.

The module defines the following functions:

Gamestate.new()New gamestate
Gamestate.switch(to, ...)Switch gamestate
Gamestate.update(dt)Call update callback
Gamestate.draw()Call draw callback
Gamestate.keypressed(key, unicode)Call keypressed callback
Gamestate.keyreleased(key)Call keyreleased callback
Gamestate.mousereleased(x,y,btn)Call mousereleased callback
Gamestate.registerEvents()Register all callbacks

function Gamestate.new()^ top Create a new gamestate.
Returns:The new (but empty) gamestate object.
function Gamestate.switch(to, ...)^ top Switch the gamestate.

Calls leave() on the currently active gamestate.

Calls enter(current, ...) on the target gamestate, where current is the gamestate before the switch and ... are the additionals arguments given to Gamestate.switch.

Parameters:[gamestate]to:target gamestate.
...:additional arguments to pass
Returns:the result of to:enter(current, ...)
function Gamestate.update(dt)^ top Calls update(dt) on current gamestate.
function Gamestate.draw()^ top Calls draw() on current gamestate.
function Gamestate.keypressed(key, unicode)^ top Calls keypressed(key, unicode) on current gamestate.
function Gamestate.keyreleased(key)^ top Calls keyreleased(key) on current gamestate.
function Gamestate.mousereleased(x,y,btn)^ top Calls mousereleased(x,y,btn) on the current gamestate.
function Gamestate.registerEvents()^ top Registers all above events so you don't need to call then in your love.* routines.

It is an error to call this anywhere else than love.load(), since it overwrites the callbacks. Dont worry though, your callbacks will still be executed.

List of callbacks

Each gamestate can have a list of callbacks:^ top
enter(previous, ...) Gets called upon entering the state. Don't call this yourself, use Gamestate.switch instead.
leave() Gets called upon leaving the state. The same warning as with enter applies.
update(dt) Manully called by Gamestate.update, or automatically like love.update when using Gamestate.registerEvents().
draw() Manully called by Gamestate.draw, or automatically like love.draw
keypressed(key, unicode) Manully called by Gamestate.keypressed, or automatically like love.keypressed
keyreleased(key) Manully called by Gamestate.keyreleased, or automatically like love.keyreleased
mousereleased(x,y,btn) Manully called by Gamestate.mousereleased, or automatically like love.mousereleased

License^ top

Yay, free software:

Copyright (c) 2010 Matthias Richter

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.

Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization.

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.

Download^ top

You can download this project in either zip or tar formats.

You can also clone the project with Git by running:

$ git clone git://github.com/vrld/hump