How to qucikly extract quads from a sprite sheet?

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rougan
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How to qucikly extract quads from a sprite sheet?

Post by rougan » Tue Oct 06, 2015 4:06 pm

Hi there!
I have around 150 different images in a spritesheet that I need to save as quads in my game. However, this takes absolutely agesto figure out the values and type out (x and y on spritesheet and the size of the quad). Most of the images are (slighty) different sizes so I don't think I can use a for loop to load them as there is no recurring pattern?
If anyone has any tips/tricks that'd be great, thanks! :)

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TheMeq
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Re: How to qucikly extract quads from a sprite sheet?

Post by TheMeq » Tue Oct 06, 2015 4:43 pm

I would re-arrange your sprite sheet so that all of your sprites are of a uniform size that will allow you to use a loop. It would probably take more processing power trying to read the image to detect the borders of your sprites then it would just to cut them all up at the same size.

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0x72
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Re: How to qucikly extract quads from a sprite sheet?

Post by 0x72 » Tue Oct 06, 2015 5:17 pm

you can introduce some automated spritesheet generator into your pipeline google suggests this one but I have no idea if it's any good: https://www.codeandweb.com/texturepacker (edit: didn't noticed but it looks like it's a paid app - you consider if worth it for 150 images, in case it's not I suppose there are some alternatives)

or (as it's just 150 images) you can come up with some little tool like the one below and select the quads by hand end export to own lua file (if you add reading from file + naming the quads with love.textinput it would be actually useful :)):

Code: Select all

local lg = love.graphics
local img
local quads = {}
local cquad = nil

function love.load()
  img = lg.newImage('img.jpg')
end

function love.draw()
  lg.setColor(255, 255, 255)
  lg.draw(img, 0, 0)
  if cquad then
    lg.setColor(255, 0, 0)
    local mx, my = love.mouse.getPosition()
    lg.rectangle('line', cquad.x+0.5, cquad.y+0.5, mx-cquad.x, my-cquad.y )
    lg.print(mx .. ', ' .. my, mx + 10, my)
  end
  for index, q in ipairs(quads) do
    lg.setColor(20, 20, 20)
    lg.print(index, q.x, q.y - 15)
    lg.rectangle('line', q.x + 0.5, q.y + 0.5, q.w, q.h)
    lg.setColor(200, 200, 200)
    lg.rectangle('line', q.x + 1.5, q.y + 1.5, q.w, q.h)
  end
end

function love.mousepressed(x, y, btn)
  if btn == 'l' or btn == 1 then
    cquad = { x = x, y = y }
  end
end

function love.keypressed(key)
  if key == 'return' then
    local fp = io.open('out.lua', 'w+')
    fp:write('return {')
    for index, q in ipairs(quads) do
      fp:write('\n  { x = '.. q.x .. ', y = '.. q.y .. ', w = '.. q.w .. ', h = '.. q.h .. ', id = '.. index .. ' }')
      if index ~= #quads then fp:write(',') end
    end
    fp:write('\n}\n')
    fp:close()
  elseif key == 'backspace' then
    quads[#quads] = nil
  end
end

function love.mousereleased(x, y, btn)
  if cquad and (btn == 'l' or btn == 1) then
    local qx, qy

    qx = math.min(x, cquad.x)
    qy = math.min(y, cquad.y)
    cquad.w = math.max(x, cquad.x) - qx
    cquad.h = math.max(y, cquad.y) - qy
    cquad.x = qx
    cquad.y = qy

    quads[#quads+1] = cquad
    cquad = nil
  end
end

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josefnpat
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Re: How to qucikly extract quads from a sprite sheet?

Post by josefnpat » Tue Oct 06, 2015 6:30 pm

0x72 wrote:you can introduce some automated spritesheet generator into your pipeline google suggests this one but I have no idea if it's any good: https://www.codeandweb.com/texturepacker (edit: didn't noticed but it looks like it's a paid app - you consider if worth it for 150 images, in case it's not I suppose there are some alternatives)
Take a look at urraka's texpack!
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rougan
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Re: How to qucikly extract quads from a sprite sheet?

Post by rougan » Tue Oct 06, 2015 6:58 pm

0x72 wrote:you can introduce some automated spritesheet generator into your pipeline google suggests this one but I have no idea if it's any good: https://www.codeandweb.com/texturepacker (edit: didn't noticed but it looks like it's a paid app - you consider if worth it for 150 images, in case it's not I suppose there are some alternatives)

or (as it's just 150 images) you can come up with some little tool like the one below and select the quads by hand end export to own lua file (if you add reading from file + naming the quads with love.textinput it would be actually useful :)):

Thank you so much, I hadn't thought of approaching it this way before! I think i'll try and make my own tool for educational purposes! :P Thanks again!

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airstruck
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Re: How to qucikly extract quads from a sprite sheet?

Post by airstruck » Tue Oct 06, 2015 7:16 pm

Another thing you could try is linking or embedding the sprite sheet in an svg that's the same size, and then drawing rectangles around all your sprites. Then change the id attribute of each rectangle to something that represents the sprite, and use xpath to export all the rectangle geometry to a Lua table. I'm using inkscape and xmlstarlet to do this and it works pretty well. Here's an example using an svgz where each rectangle has an id starting with "sprite."

Code: Select all

atlas='resource/atlas.lua'

echo 'return {' > $atlas
gzip -dk -S svgz resource/sprite.svgz -c | \
xmlstarlet sel -T -t -m '//svg:rect[starts-with(@id,"sprite.")]' \
-o "['" -v "substring-after(@id, 'sprite.')" \
-o "'] = { x = " -v "@x" -o ", y = " -v "@y" \
-o ", width = " -v "@width" \
-o ", height = " -v "@height" -o " }, " -n >> $atlas
echo '}' >> $atlas

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