View difference between Paste ID: s4qQgw3K and LVP1mWJG

 --[[
 	GameUtil
 	An API for drawing sprites and animations made in NPaintPro
 	By NitrogenFingers
 ]]--
 
 
 --The back buffer. Initialized as nil
 local backbuffer = nil
 --The bounds of the terminal the back buffer displays to
 local tw,th = nil, nil
 
 --[[Constructs a new buffer. This must be done before the buffer can written to.
 	Params: terminal:?table = The function table to draw to a screen. By default (nil) this refers
 			to the native terminal, but monitor displays can be passed through as well:
 			local leftMonitor = peripherals.wrap("left")
 			initializeBuffer(leftMonitor)
 	Returns:boolean = True if the buffer was successfully initialized; false otherwise
 ]]--
 function initializeBuffer(terminal)
 	if not terminal then terminal = term end
 	if not terminal.getSize then
 		error("Parameter cannot be used to initialize the backbuffer.")
 	end
 	if not terminal.isColour() then
 		error("Parameter does not represent an advanced computer.")
 	end
 
 	tw,th = terminal.getSize()
 	backbuffer = { }
 	for y=1,th do
 		backbuffer[y] = { }
 	end
 	return true
 end
 
 --[[Will clear the buffer and reset to nil, or to a colour if provided
 	Params: colour:?number = The colour to set the back buffer to
 	Returns:nil
 ]]--
 function clearBuffer(colour)
 	if not backbuffer then
 		error("Back buffer not yet initialized!")
 	end
 
 	for y=1,#backbuffer do
 		backbuffer[y] = { }
 		if colour then
 			for x=1,tw do
 				backbuffer[y][x] = colour
 			end
 		end
 	end
 end
 
 --[[Draws the given entity to the back buffer
 	Params: entity:table = the entity to draw to the buffer
 	Returns:nil
 ]]--
 function writeToBuffer(entity)
 	if not backbuffer then
 		error("Back buffer not yet initialized!")
 	end
 
 	local image = nil
 	if entity.type == "animation" then
 		image = entity.frames[entity.currentFrame]
 	else
 		image = entity.image
 	end
 
 	for y=1,image.dimensions.height do
 		for x=1,image.dimensions.width do
 			if image[y][x] then
 				local xpos,ypos = x,y
 				if entity.mirror.x then xpos = image.dimensions.width - x + 1 end
 				if entity.mirror.y then ypos = image.dimensions.height - y + 1 end
 
-				backbuffer[entity.y + ypos - 1][entity.x + xpos - 1]
+				--If the YPos doesn't exist, no need to loop through the rest of X!
-					= image[y][x]
+				--Don't you love optimization?
 				if not backbuffer[entity.y + ypos - 1] then break end
 
 				backbuffer[entity.y + ypos - 1][entity.x + xpos - 1] = image[y][x]
 			end
 		end
 	end
 end
 
 --[[Draws the contents of the buffer to the screen. This will not clear the screen or the buffer.
 	Params: terminal:table = the terminal to draw to
 	Returns:nil
 ]]--
 function drawBuffer(terminal)
 	if not backbuffer then
 		error("Back buffer not yet initialized!")
 	end
 	if not terminal then terminal = term end
 	if not terminal.setCursorPos or not terminal.setBackgroundColour or not terminal.write then
 		error("Parameter cannot be used to initialize the backbuffer.")
 	end
 	if not terminal.isColour() then
 		error("Parameter does not represent an advanced computer.")
 	end
 
 	for y=1,math.min(#backbuffer, th) do
 		for x=1,tw do
 			if backbuffer[y][x] then
 				terminal.setCursorPos(x,y)
 				terminal.setBackgroundColour(backbuffer[y][x])
 				terminal.write(" ")
 			end
 		end
 	end
 end
 
 --[[Converts a hex digit into a colour value
 	Params: hex:?string = the hex digit to be converted
 	Returns:string A colour value corresponding to the hex, or nil if the character is invalid
 ]]--
 local function getColourOf(hex)
 	local value = tonumber(hex, 16)
 	if not value then return nil end
 	value = math.pow(2,value)
 	return value
 end
 
 --[[Converts every pixel of one colour in a given sprite to another colour
 	Use for "reskinning". Uses OO function.
 	Params: self:sprite = the sprite to reskin
 			oldcol:number = the colour to replace
 			newcol:number = the new colour
 	Returns:nil
 ]]--
 local function repaintS(self, oldcol, newcol)
 	for y=1,self.image.bounds.height do
 		for x=1, self.image.bounds.width do
 			if self.image[y][x] == oldcol then
 				self.image[y][x] = newcol
 			end
 		end
 	end
 end
 
 --[[Converts every pixel of one colour in a given animation to another colour
 	Use for "reskinning". Uses OO function.
 	Params: self:animation = the animation to reskin
 			oldcol:number = the colour to replace
 			newcol:number = the new colour
 	Returns:nil
 ]]--
 local function repaintA(self, oldcol, newcol)
 	for f=1,#self.frames do
 		print(self.frames[f].bounds)
 		for y=1,self.frames[f].bounds.height do
 			for x=1, self.frames[f].bounds.width do
 				if self.frames[f][y][x] == oldcol then
 					self.frames[f][y][x] = newcol
 				end
 			end
 		end
 	end
 end
 
 --[[Prints the sprite on the screen
 	Params: self:sprite = the sprite to draw
 	Returns:nil
 ]]--
 local function drawS(self)
 	local image = self.image
 
 	for y=1,image.dimensions.height do
 		for x=1,image.dimensions.width do
 			if image[y][x] then
 				local xpos,ypos = x,y
 				if self.mirror.x then xpos = image.dimensions.width - x + 1 end
 				if self.mirror.y then ypos = image.dimensions.height - y + 1 end
 
 				term.setBackgroundColour(image[y][x])
 				term.setCursorPos(self.x + xpos - 1, self.y + ypos - 1)
 				term.write(" ")
 			end
 		end
 	end
 end
 
 --[[Prints the current frame of the animation on screen
 	Params: self:anim = the animation to draw
 			frame:?number = the specific frame to draw (default self.currentFrame)
 	Returns:nil
 ]]--
 local function drawA(self, frame)
 	if not frame then frame = self.currentFrame end
 	local image = self.frames[frame]
 
 	for y=1,image.dimensions.height do
 		for x=1,image.dimensions.width do
 			if image[y][x] then
 				local xpos,ypos = x,y
 				if self.mirror.x then xpos = image.dimensions.width - x + 1 end
 				if self.mirror.y then ypos = image.dimensions.height - y + 1 end
 
 				term.setBackgroundColour(image[y][x])
 				term.setCursorPos(self.x + xpos - 1, self.y + ypos - 1)
 				term.write(" ")
 			end
 		end
 	end
 end
 
 --[[Checks the animation timer provided to see whether or not the animation needs to be updated.
 	If so, it makes the necessary change.
 	Params: self:animation = the animation to be updated
 			timerID:number = the ID of the most recent timer event
 	Returns:bool = true if the animation was update; false otherwise
 ]]--
 local function updateA(self, timerID)
 	if self.timerID and timerID and self.timerID == timerID then
 		self.currentFrame = self.currentFrame + 1
 		if self.currentFrame > self.upperBound then
 			self.currentFrame = self.lowerBound
 		end
 		return true
 	else
 		return false
 	end
 end
 
 --[[Moves immediately to the next frame in the sequence, as though an update had been called.
 	Params: self:animation = the animation to update
 	Returns:nil
 ]]--
 local function nextA(self)
 	self.currentFrame = self.currentFrame + 1
 	if self.currentFrame > self.upperBound then
 		self.currentFrame = self.lowerBound
 	end
 end
 
 --[[Moves immediately to the previous frame in the sequence
 	Params: self:animation = the animation to update
 	Returns:nil
 ]]--
 local function previousA(self)
 	self.currentFrame = self.currentFrame - 1
 	if self.currentFrame < self.lowerBound then
 		self.currentFrame = self.upperBound
 	end
 end
 
 --[[A simple debug function that displays the outline of the bounds
 	on a given shape. Useful when testing collision detection or other game
 	features.
 	Params: entity:table = the bounded entity to represent
-	error("not implemented yet...")
+			colour:?number = the colour to draw the rectangle (default red)
 	Returns:nil
 ]]--
 local function drawBounds(entity, colour)
-	type. Bases collision on a pixel occupancy approach.
+	if not colour then colour = colours.red end
 	local image = nil
 	if entity.type == "animation" then image = entity.frames[entity.currentFrame]
 	else image = entity.image end
 
 	term.setBackgroundColour(colour)
-	error("not implemented yet..")
+
 	corners = {
 		topleft = { x = entity.x + image.bounds.x - 1, y = entity.y + image.bounds.y - 1 };
 		topright = { x = entity.x + image.bounds.x + image.bounds.width - 2, y = entity.y + image.bounds.y - 1 };
 		botleft = { x = entity.x + image.bounds.x - 1, y = entity.y + image.bounds.y + image.bounds.height - 2 };
 		botright = { x = entity.x + image.bounds.x + image.bounds.width - 2, y = entity.y + image.bounds.y + image.bounds.height - 2 };
 	}
 
 	term.setCursorPos(corners.topleft.x, corners.topleft.y)
 	term.write(" ")
 	term.setCursorPos(corners.topright.x, corners.topright.y)
 	term.write(" ")
 	term.setCursorPos(corners.botleft.x, corners.botleft.y)
 	term.write(" ")
 	term.setCursorPos(corners.botright.x, corners.botright.y)
 	term.write(" ")
 end
 
 --[[Creates a bounding rectangle object. Used in drawing the bounds and the rCollidesWith methods
 	Params: self:table = the entity to create the rectangle
 	Returns:table = the left, right, top and bottom edges of the rectangle
 ]]--
 local function createRectangle(entity)
 	local image = nil
 	if entity.type == "animation" then
 		image = entity.frames[entity.currentFrame]
 	else
 		image = entity.image
 	end
 	--Note that the origin is always 1, so we subtract 1 for every absolute coordinate we have to test.
 	return {
 		left = entity.x + image.bounds.x - 1;
 		right = entity.x + image.bounds.x + image.bounds.width - 2;
 		top = entity.y + image.bounds.y - 1;
 		bottom = entity.y + image.bounds.y + image.bounds.height - 2;
 	}
 end
 
 --[[Performs a rectangle collision with another given entity. Entity can be of sprite or animation
 	type (also true of the self). Bases collision using a least squared approach (rectangle precision).
 	Params: self:sprite,animation = the object in question of the testing
 			other:sprite,animation = the other object tested for collision
 	Returns:bool = true if bounding rectangle intersect is true; false otherwse
 ]]--
 local function rCollidesWith(self, other)
 	--First we construct the rectangles
 	local img1C, img2C = createRectangle(self), createRectangle(other)
 
 	--We then determine the "relative position" , in terms of which is farther left or right
 	leftmost,rightmost,topmost,botmost = nil,nil,nil,nil
 	if img1C.left < img2C.left then
 		leftmost = img1C
 		rightmost = img2C
 	else
 		leftmost = img2C
 		rightmost = img1C
 	end
 	if img1C.top < img2C.top then
 		topmost = img1C
-			file:close()
+		botmost = img2C
 	else
 		topmost = img2C
 		botmost = img1C
 	end
 
 	--Then we determine the distance between the "extreme" edges-
 		--distance between leftmost/right edge and rightmost/left edge
 		--distance between topmost/bottom edge and bottommost/top edge
 	local xdist = rightmost.left - leftmost.right
 	local ydist = botmost.top - topmost.bottom
 
 	--If both are negative, our rectangles intersect!
 	return xdist <= 0 and ydist <= 0
 end
 
 --[[Performs a pixel collision test on another given entity. Either entity can be of sprite or animation
 	type. This is done coarsegrain-finegrain, we first find the intersection between the rectangles
 	(if there is one), and then test the space within that intersection for any intersecting pixels.
 	Params: self:sprite,animation = the object in question of the testing
 			other:sprite,animation = the other object being tested for collision
 	Returns:?number,?number: The X and Y position in which the collision occurred.
 ]]--
 local function pCollidesWith(self, other)
 	--Identically to rCollidesWith, we create our rectangles...
 	local img1C, img2C = createRectangle(self), createRectangle(other)
 	--We'll also need the images to compare pixels later
 	local img1, img2 = nil,nil
 	if self.type == "animation" then img1 = self.frames[self.currentFrame]
 	else img1 = self.image end
 	if other.type == "animation" then img2 = other.frames[other.currentFrame]
 	else img2 = other.image end
 
 	--...then we position them...
 	leftmost,rightmost,topmost,botmost = nil,nil,nil,nil
 	--We also keep track of which is left and which is right- it doesn't matter in a rectangle
 	--collision but it does in a pixel collision.
 	img1T,img2T = {},{}
 
 	if img1C.left < img2C.left then
 		leftmost = img1C
 		rightmost = img2C
 		img1T.left = true
 	else
 		leftmost = img2C
 		rightmost = img1C
 		img2T.left = true
 	end
 	if img1C.top < img2C.top then
 		topmost = img1C
 		botmost = img2C
 		img1T.top = true
 	else
 		topmost = img2C
 		botmost = img1C
 		img2T.top = true
 	end
 
 	--...and we again find the distances between the extreme edges.
 	local xdist = rightmost.left - leftmost.right
 	local ydist = botmost.top - topmost.bottom
 
 	--If these distances are > 0 then we stop- no need to go any farther.
 	if xdist > 0 or ydist > 0 then return false end
 
 
 	for x = rightmost.left, rightmost.left + math.abs(xdist) do
 		for y = botmost.top, botmost.top + math.abs(ydist) do
 			--We know a collision has occurred if a pixel is occupied by both images. We do this by
 			--first transforming the coordinates based on which rectangle is which, then testing if a
 			--pixel is at that point
 				-- The leftmost and topmost takes the distance on x and y and removes the upper component
 				-- The rightmost and bottommost, being the farther extremes, compare from 1 upwards
 			local testX,testY = 1,1
 			if img1T.left then testX = x - img1C.left + 1
 			else testX = x - img1C.left + 1 end
 			if img1T.top then testY = y - img1C.top + 1
 			else testY = y - img1C.top + 1 end
 
 			local occupy1 = img1[testY + img1.bounds.y-1][testX + img1.bounds.x-1] ~= nil
 
 			if img2T.left then testX = x - img2C.left + 1
 			else testX = x - img2C.left + 1 end
 			if img2T.top then testY = y - img2C.top + 1
 			else testY = y - img2C.top + 1 end
 
 			local occupy2 = img2[testY + img2.bounds.y-1][testX + img2.bounds.x-1] ~= nil
 
 			if occupy1 and occupy2 then return true end
 		end
 	end
 	--If the looop terminates without returning, then no pixels overlap
 	return false
 end
 
 --[[
 	Sprites Fields:
 x:number = the x position of the sprite in the world
 y:number = the y position of the sprite in the world
 image:table = a table of the image. Indexed by height, a series of sub-tables, each entry being a pixel
 		at [y][x]. It also contains:
 	bounds:table =
 		x:number = the relative x position of the bounding rectangle
 		y:number = the relative y position of the bounding rectangle
 		width:number = the width of the bounding rectangle
 		height:number = the height of the bounding rectangle
 	dimensions:table =
 		width = the width of the entire image in pixels
 		height = the height of the entire image in pixels
 
 mirror:table =
 	x:bool = whether or not the image is mirrored on the X axis
 	y:bool = whether or not the image is mirrored on the Y axis
 repaint:function = see repaintS (above)
 rCollidesWith:function = see rCollidesWith (above)
 pCollidesWith:function = see pCollidesWith (above)
 draw:function = see drawS (above)
 ]]--
 
 --[[Loads a new sprite into a table, and returns it to the user.
 	Params: path:string = the absolute path to the desired sprite
 	x:number = the initial X position of the sprite
 	y:number = the initial Y position of the sprite
 ]]--
 function loadSprite(path, x, y)
 	local sprite = {
 		type = "sprite",
 		x = x,
 		y = y,
 		image = { },
 		mirror = { x = false, y = false }
 	}
 
 	if fs.exists(path) then
 		local file = io.open(path, "r" )
 		local leftX, rightX = math.huge, 0
 		local topY, botY = nil,nil
 
 		local lcount = 0
 		for line in file:lines() do
 			lcount = lcount+1
 			table.insert(sprite.image, {})
 			for i=1,#line do
 				if string.sub(line, i, i) ~= " " then
 					leftX = math.min(leftX, i)
 					rightX = math.max(rightX, i)
 					if not topY then topY = lcount end
 					botY = lcount
 				end
 				sprite.image[#sprite.image][i] = getColourOf(string.sub(line,i,i))
 			end
 		end
 		file:close()
 
 		sprite.image.bounds = {
 			x = leftX,
 			width = rightX - leftX + 1,
 			y = topY,
 			height = botY - topY + 1
 		}
 		sprite.image.dimensions = {
 			width = rightX,
 			height = botY
 		}
 
 		sprite.x = sprite.x - leftX + 1
 		sprite.y = sprite.y - topY + 1
 
 		sprite.repaint = repaintS
 		sprite.rCollidesWith = rCollidesWith
 		sprite.pCollidesWith = pCollidesWith
 		sprite.draw = drawS
 		return sprite
 	else
 		error(path.." not found!")
 	end
 end
 
 --Animations contain
 	--Everything a sprite contains, but the image is a series of frames, not just one image
 	--An timerID that tracks the last animation
 	--An upper and lower bound on the active animation
 	--An update method that takes a timer event and updates the animation if necessary
 
 --[[
 
 ]]--
 function loadAnimation(path, x, y, currentFrame)
 	local anim = {
 		type = "animation",
 		x = x,
 		y = y,
 		frames = { },
 		mirror = { x = false, y = false },
 		currentFrame = currentFrame
 	}
 
 	table.insert(anim.frames, { })
 	if fs.exists(path) then
 		local file = io.open(path, "r")
 		local leftX, rightX = math.huge, 0
 		local topY, botY = nil,nil
 
 		local lcount = 0
 		for line in file:lines() do
 			lcount = lcount+1
 			local cFrame = #anim.frames
 			print("["..line.."]")
 			if line == "~" then
 				print(leftX," ",rightX," ",topY," ",botY)
 				anim.frames[cFrame].bounds = {
 					x = leftX,
 					y = topY,
 					width = rightX - leftX + 1,
 					height = botY - topY + 1
 				}
 				anim.frames[cFrame].dimensions = {
 					width = rightX,
 					height = botY
 				}
 				table.insert(anim.frames, { })
 				leftX, rightX = math.huge, 0
 				topY, botY = nil,nil
 				lcount = 0
 			else
 				table.insert(anim.frames[cFrame], {})
 				for i=1,#line do
 					if string.sub(line, i, i) ~= " " then
 						leftX = math.min(leftX, i)
 						rightX = math.max(rightX, i)
 						if not topY then topY = lcount end
 						botY = lcount
 					end
 					anim.frames[cFrame][#anim.frames[cFrame]] [i] = getColourOf(string.sub(line,i,i))
 				end
 			end
 		end
 		file:close()
 		local cFrame = #anim.frames
 		anim.frames[cFrame].bounds = {
 			x = leftX,
 			y = topY,
 			width = rightX - leftX + 1,
 			height = botY - topY + 1
 		}
 
 		if not currentFrame or type(currentFrame) ~= "number" or currentFrame < 1 or
 				currentFrame > #anim.frames then
 			anim.currentFrame = 1
 		end
 
 		print("continue")
 		os.pullEvent("key")
 
 		anim.timerID = nil
 		anim.lowerBound = 1
 		anim.upperBound = #anim.frames
 		anim.updating = false
 
 		anim.repaint = repaintA
 		anim.rCollidesWith = rCollidesWith
 		anim.pCollidesWith = pCollidesWith
 		anim.draw = drawA
 		anim.update = updateA
 		anim.next = nextA
 		anim.previous = previousA
 		return anim
 	else
 		error(path.." not found!")
 	end
 end