Automatic image rescale

[mmanso]

Hi all,

I'm loading an image (800x600) when my app starts with:

img = love.graphics.newImage("assets/images/states/main.png")

Then, on the love.draw() I do:

love.graphics.draw(img, img.x, img.y)

This works lovely.

Now, when I resize the window (for example, to 1024x768) is there any way to make the draw rescale it? I've seen the draw functions has a "scale" option but I'm not following very well the way it should work.

Thanks a lot.

[Davidobot]

The scale can be calculated using the following formula:

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scaleX = newWidth/oldWidth
scaleY = newHeight/oldHeight

There is a call back called love.resize that passes some variable, iirc.

You can then set the scale as follows:

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love.graphics.push()
love.graphics.scale(scaleX, scaleY)
-- DRAW STUFF --
love.graphics.pop()

Disclaimer: This code is untested.

[zorg]

A scale parameter of 1.0 will give you the 1:1 (same) scale, this should be evident, as it is the default value, if you check the wiki.
Now then, if the window is smaller than the image, we need to draw the image scaled down, otherwise, if the window is larger than the image, we need to scale it up.

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local sx = love.window.getWidth() / img:getWidth()
local sy = love.window.getHeight() / img:getHeigth()

Now, this will scale the image -exactly- to the screen, which will stretch it if the aspect ratio is not the same. To combat this, we may do either of the following:

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love.graphics.draw(img, img.x, img.y, 0, math.min(sx,sy)) -- if we want the image to fit inside, or
love.graphics.draw(img, img.x, img.y, 0, math.max(sx,sy)) -- if we don't want black bars at all.

On how to center the image with the above solutions is left as an excercise to the reader

[mmanso]

Thanks! Sorry the lame questions but I'm starting with all this.

Again, thanks a lot.

[Zatherz]

I wrote a small module for scaling in pixel art games, where perfect and square pixels are important. If you're writing one, check out ScaleInator