camera.lua

-- https://github.com/davisdude/Brady
--[[
Copyright (c) 2016 Davis Claiborne

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.
]]
local function mixin( to, from ) for i, v in pairs( from or {} ) do to[i] = v end end

-- Rotate (px, py) about (ox, oy)
local function rotateAboutPoint( px, py, ox, oy, theta )
	px, py = px - ox, py - oy
	local cos, sin = math.cos( theta ), math.sin( theta )
	return px * cos - py * sin + ox, px * sin + py * cos + oy
end

local function makePush( self, layer )
	return function()
		love.graphics.push( layer.mode )
		love.graphics.origin()
		love.graphics.translate( self.x + self.offsetX, self.y + self.offsetY )
		love.graphics.rotate( self.rotation )
		love.graphics.scale( self.scale * self.aspectRatioScale * layer.scale )
		love.graphics.translate( -self.translationX * layer.relativeScale, -self.translationY * layer.relativeScale )
	end
end

local function addLayer( self, name, scale, flags )
	local new = {
		name = name,
		scale = scale,
		relativeScale = 1, -- Controls the translation speed
		mode = self.mode,
	}
	new.push = makePush( self, new )
	new.pop = love.graphics.pop

	mixin( new, flags )

	self.layers[name] = new
	return new
end

local function newCamera( w, h, flags )
	local scale, scaleW, scaleH

	local new = {
		-- Attributes
		x = 0, y = 0,
		w = w, h = h,
		translationX = 0, translationY = 0,
		offsetX = w / 2, offsetY = h / 2,
		scale = 1,
		rotation = 0,
		resizable = false,
		maintainAspectRatio = false,
		center = false,
		aspectRatioScale = 1, -- Controls scale due to resizing
		mode = 'transform',
		layers = {},
		-- General Functions
		update = function( self, containerW, containerH )
			if self.resizable then self:resizingFunction( self:getContainerDimensions() ) end
		end,
		resizingFunction = function( self, containerW, containerH )
			if self.maintainAspectRatio then
				containerW, containerH = containerW - 2 * self.x, containerH - 2 * self.y
				scaleW, scaleH = containerW / self.w, containerH / self.h
				scale = math.min( scaleW, scaleH )
				self.w, self.h = scale * self.w, scale * self.h
			else
				self.w, self.h = containerW - 2 * self.x, containerH - 2 * self.y
			end
			self.aspectRatioScale = self.w / w
			self.offsetX, self.offsetY = self.w / 2, self.h / 2

			if self.center then
				self.offsetX = self.offsetX + (containerW - self.w) / 2
				self.offsetY = self.offsetY + (containerH - self.h) / 2
			end
		end,
		getContainerDimensions = function( self ) return love.graphics.getDimensions() end,
		addLayer = addLayer,
		getLayer = function( self, name )
			return ( type( name ) == 'table' and name or self.layers[name] )
		end,
		push = function( self, layer ) self:getLayer( layer or 'main' ):push() end,
		pop = function( self, layer ) self:getLayer( layer or 'main' ):pop() end,
		getWorldCoordinates = function( self, x, y, layer )
			layer = self:getLayer( layer or 'main' )
			local scaleFactor = self.scale * self.aspectRatioScale * layer.scale
			x, y = x - self.x - self.offsetX, y - self.y - self.offsetY
			x, y = rotateAboutPoint( x, y, 0, 0, -self.rotation )
			x, y = x / scaleFactor, y / scaleFactor
			return x + self.translationX * layer.relativeScale, y + self.translationY * layer.relativeScale
		end,
		getScreenCoordinates = function( self, x, y, layer )
			layer = self:getLayer( layer or 'main' )
			local scaleFactor = self.scale * self.aspectRatioScale * layer.scale
			x, y = x - self.translationX / layer.relativeScale, y - self.translationY * layer.relativeScale
			x, y = x * scaleFactor, y * scaleFactor
			x, y = rotateAboutPoint( x, y, 0, 0, self.rotation )
			x, y = x + self.x + self.offsetX, y + self.y + self.offsetY
			return x, y
		end,
		getMouseWorldCoordinates = function( self, layer )
			layer = self:getLayer( layer or 'main' )
			local x, y = love.mouse.getPosition()
			return self:getWorldCoordinates( x, y, layer )
		end,
		increaseScaleToPoint = function( self, ds, wx, wy )
			if not wx then
				wx, wy = self:getMouseWorldCoordinates()
			end

			local tx, ty = self:getTranslation()
			self:increaseScale( ds )
			self:increaseTranslation( ( wx - tx ) * ds / self.scale, ( wy - ty ) * ds / self.scale )
		end,
		scaleToPoint = function( self, s, wx, wy )
			if not wx then
				wx, wy = self:getMouseWorldCoordinates()
			end

			local tx, ty = self:getTranslation()
			self:scaleBy( s )
			self:increaseTranslation( ( wx - tx ) * ( 1 - 1 / s ), ( wy - ty ) * ( 1 - 1 / s ) )
		end,
		-- Getters/setters
		setViewportPosition = function( self, x, y ) self.x, self.y = x, y end,
		getViewportPosition = function( self ) return self.x, self.y end,
		setOffset = function( self, x, y ) self.offsetX, self.offsetY = x, y end,
		getOffset = function( self ) return self.offsetX, self.offsetY end,
		setTranslation = function( self, x, y ) self.translationX, self.translationY = x or 0, y or 0 end,
		getTranslation = function( self ) return self.translationX, self.translationY end,
		increaseTranslation = function( self, dx, dy ) self.translationX, self.translationY = self.translationX + dx, self.translationY + dy end,
		setRotation = function( self, theta ) self.rotation = theta end,
		getRotation = function( self ) return self.rotation end,
		increaseRotation = function( self, dr ) self.rotation = self.rotation + dr end,
		setScale = function( self, s ) self.scale = s end,
		getScale = function( self ) return self.scale end,
		increaseScale = function( self, ds ) self.scale = self.scale + ds end,
		scaleBy = function( self, ds ) self.scale = self.scale * ds end,
	}
	new.translate = new.increaseTranslation
	new.rotate = new.increaseRotation

	mixin( new, flags )
	addLayer( new, 'main', 1 )

	if new.center then
		local containerW, containerH = new:getContainerDimensions()
		new.offsetX = new.offsetX + (containerW - new.w) / 2
		new.offsetY = new.offsetY + (containerH - new.h) / 2
	end

	return new
end


return setmetatable( { new = newCamera, }, { __call = function( _, ... ) return newCamera( ... ) end } )