Watch the stars fly!

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Kingdaro
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Watch the stars fly!

Post by Kingdaro » Sun Nov 21, 2010 9:48 pm

A little somethin' I decided to whip up in a couple hours.
Stars.love
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Stars ver 2.love
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Last edited by Kingdaro on Mon Nov 22, 2010 8:26 pm, edited 1 time in total.

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arquivista
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Re: Watch the stars fly!

Post by arquivista » Sun Nov 21, 2010 10:39 pm

Kingdaro wrote:A little somethin' I decided to whip up in a couple hours.
Stars.love
Hi! That remember more snow fall than stars but is always a nice effect. Look, shouldn't be a Mac issue but it seems that from time to time things stop a bit. Let's wait for other reports to see if it's only happening here. Also stars animation/trail isn't quite smooth. Probably something could be improved. Keep the good work in this demo!
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Kingdaro
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Re: Watch the stars fly!

Post by Kingdaro » Sun Nov 21, 2010 11:06 pm

arquivista wrote:
Kingdaro wrote:A little somethin' I decided to whip up in a couple hours.
Stars.love
Hi! That remember more snow fall than stars but is always a nice effect. Look, shouldn't be a Mac issue but it seems that from time to time things stop a bit. Let's wait for other reports to see if it's only happening here. Also stars animation/trail isn't quite smooth. Probably something could be improved. Keep the good work in this demo!
Thanks for the feedback.

I plan to add a stars counter at the top of the screen (already did) and I want to make it more customizable, like setting speed or color or image or direction, etc.

From the stars counter I concluded that the game gets slower/laggier because of the amount of stars in the game constantly increasing. Here's my part of the script to fix it, and what came up when I tried to do this. The chunk added in is surrounded by comment brackets, and the number sign is where the error occurred, according to the blue screen of death.

Code: Select all

stars = {}
time = 1
function love.update(dt)
	if math.random(1,2) == 2 then
		local star = {}
		star.x = math.random(0,640)
		star.y = -100
		star.size = math.random(0.4,2.5)
		table.insert(stars,star)
	end
	
	for i=1, #stars do
		if stars[i] ~= nil then
			stars[i].y = stars[i].y+(150*dt*stars[i].size)
		end
	end
--[[
	for i=1, #stars do 
		if stars[i].y >= 480 then --#main.lua.24 attempt to index field ? (a nil value)
			table.remove(stars,i) 
		end
	end
--]]
	if time >= 1 then
		love.graphics.setCaption("Watch the stars fly! ("..love.timer.getFPS().." FPS)")
		time = 0
	else
		time = time+dt
	end
end
I can't seem to find a way to fix this.

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Mud
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Re: Watch the stars fly!

Post by Mud » Mon Nov 22, 2010 12:03 am

Here's an attempt at using the particle system for a star field (move mouse around to 'turn'):

Code: Select all

local stars, center

function love.load()
   center = {
      x = love.graphics.getWidth()/2,
      y = love.graphics.getHeight()/2,
   }
   stars = love.graphics.newParticleSystem( love.graphics.newImage('fire.png'), 300 )
   stars:setPosition(center.x, center.y)
   stars:setBufferSize( 2000 )
   stars:setEmissionRate( 300 )
   stars:setLifetime( -1 )
   stars:setParticleLife( 6 )
   stars:setColor( 55, 55, 55, 0, 255, 255, 255, 255 )
   stars:setSize( 0.16, 0.1, 1 )
   stars:setSpeed( 30, 80  )
   stars:setSpread( math.rad(360) )
   stars:setRadialAcceleration( 20 )
end

function love.keypressed(key)
   if key == 'escape' then os.exit() end
end

function love.update(dt)
   local x, y = love.mouse.getPosition()
   stars:setOffset((x-center.x) * -5, (y-center.y) * -5)
   stars:update(dt)
end

function love.draw()
   love.graphics.draw(stars, 0, 0)
end
Attachments
stars.love
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TechnoCat
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Re: Watch the stars fly!

Post by TechnoCat » Mon Nov 22, 2010 12:51 am

Code: Select all

love.graphics.draw(love.graphics.newImage("star.png"),stars[i].x,stars[i].y,0,stars[i].size/4)
nonononono

Create the image only once!
for instance, look in love.load and love.draw for stars.image:

Code: Select all

math.randomseed( os.time() )

function love.load()
	win = love.graphics.setMode(640,480)
	stars = {}
	time = 1
	stars.image = love.graphics.newImage("star.png")
	f = love.graphics.newFont(12)
	love.graphics.setFont(f)
end

function love.update(dt)
	if math.random(1,2) == 2 then
		local star = {}
		star.x = math.random(0,640)
		star.y = -128
		star.size = math.random(0.5,2)
		table.insert(stars,star)
	end
	
	for i,star in ipairs(stars) do
		if star.y < 480 then
			star.y = star.y+(150*dt*star.size)
		else
			table.remove(stars,i)
		end
	end
	
	if time >= 1 then
		love.graphics.setCaption("Watch the stars fly! ("..love.timer.getFPS().." FPS)")
		time = 0
	else
		time = time+dt
	end
end

function love.draw()
	for _,star in ipairs(stars) do
		love.graphics.draw(stars.image,star.x,star.y,0,star.size/4)
	end
end
And by the way, there is a problem with this in your love.update(dt):

Code: Select all

	if math.random(1,2) == 2 then
		local star = {}
		star.x = math.random(0,640)
		star.y = -40
		star.size = math.random(0.5,2)
		table.insert(stars,star)
	end
Since you are tying it to frame instead of time, people with higher framerates will get more stars falling.
Simply making it something like

Code: Select all

if math.random(1,2) == 2 and time>=1 then
should fix it for now. But you'll probably want the frequency to be greater than an expected star every 2 seconds.

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kikito
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Re: Watch the stars fly!

Post by kikito » Mon Nov 22, 2010 9:46 am

TechnoCat wrote:

Code: Select all

love.graphics.draw(love.graphics.newImage("star.png"),stars[i].x,stars[i].y,0,stars[i].size/4)
nonononono
I fully support this nonononono.

EDIT: fixed misquote
Last edited by kikito on Mon Nov 22, 2010 1:08 pm, edited 2 times in total.
When I write def I mean function.

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Robin
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Re: Watch the stars fly!

Post by Robin » Mon Nov 22, 2010 11:10 am

I support the nonononono, but I don't support the misquote.
Help us help you: attach a .love.

nomnom
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Re: Watch the stars fly!

Post by nomnom » Mon Nov 22, 2010 3:34 pm

arquivista wrote:
Kingdaro wrote:A little somethin' I decided to whip up in a couple hours.
Stars.love
Hi! That remember more snow fall than stars but is always a nice effect.
Yea :)
Look, shouldn't be a Mac issue but it seems that from time to time things stop a bit. Let's wait for other reports to see if it's only happening here.
It is happening here too! You are not the only one...

It is well done :) Stay tuned (I hope the translations service of my choice choosed the right idiom :roll:)

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Kingdaro
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Re: Watch the stars fly!

Post by Kingdaro » Mon Nov 22, 2010 8:21 pm

Thanks everyone for the ideas! The current state of the demo is excellent! I couldn't have done it without all your help. ^^

Also, I'm much more comfortable with using for i=1, #table since it's what I've been using ever since I started using Lua and I never really bothered to get the concept of pairs/ipairs. (I'd rather not have anybody explain it to me. :3)

So, here's the demo in all it's beautified and updated glory. (See first post.)

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Mud
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Re: Watch the stars fly!

Post by Mud » Mon Nov 22, 2010 9:07 pm

Kingdaro wrote:I'm much more comfortable with using for i=1, #table [..] I never really bothered to get the concept of pairs/ipairs
Iterating arrays that way can be faster (eliminating iterator function call overhead), but only if you index the table you're iterating no more than ~1-2 times in the loop body, and it only works for arrays. For instance:

Code: Select all

for i=1, #stars do
   stars[i].y = stars[i].y+(speed*dt*(stars[i].size/2))
end

for i,star in ipairs(stars) do
   star.y = star.y+(speed*dt*(star.size/2))
end
The second loop is faster, because we eliminate 3 table lookups, which saves more time than we lose from the iterator call (I also find it easier to read).

Kingdaro wrote:here's the demo in all it's beautified and updated glory. (See first post.)
The line "star.x = math.random(-640,1280)" is generating ~65% of your stars off-screen where they will never be seen.

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