Setting the Camera's view to another position?

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xFade
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Setting the Camera's view to another position?

Post by xFade » Mon Apr 07, 2014 8:17 pm

How can you set the camera to look at, say... (-250,0)? Is this even possible?
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Germanunkol
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Re: Setting the Camera's view to another position?

Post by Germanunkol » Mon Apr 07, 2014 8:25 pm

Hi,

Yes, this is possible. It's usually done by calling love.graphics.translate()
So what you're really doing is translating everything to (250, 0) - which has the same effect as moving the camera to (-250, 0).

Here's an example:

Code: Select all

function draw()
    -- Draw the scene at an offset of 250, 0:
    love.graphics.push()
    love.graphics.translate(250, 0)
    love.graphics.rectangle( "fill", 10, 10, 50, 50 )
    love.graphics.pop()   -- restores coordinate system to the one of the previous push()

    -- now draw the UI and everything that should NOT be moved:
    love.graphics.print( "some text", 10, 10 )
end
With that said, there are a few camera libraries out there (vrld's hump being a good example: Documentation here) which do the heavy stuff for you and hide the camera movement, rotation etc and allow for multiple cameras and similar. Check it out!
I recommend trying the way above first though, to get familiar with the concept.
trAInsported - Write AI to control your trains
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GridCars - Our jam entry for LD31
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xFade
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Re: Setting the Camera's view to another position?

Post by xFade » Mon Apr 07, 2014 8:30 pm

Thank you :D
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xFade
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Re: Setting the Camera's view to another position?

Post by xFade » Mon Apr 07, 2014 8:37 pm

Wait but I need to access the negative scale.I drew an image from another script at (-250,0) and it doesn't appear :/
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Robin
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Re: Setting the Camera's view to another position?

Post by Robin » Mon Apr 07, 2014 9:27 pm

Please upload a .love. I'm guessing a module needs to be required or a function called, but it's impossible to tell without seeing your code. (And please don't double post. You could have edited your previous post instead.)
Help us help you: attach a .love.

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mickeyjm
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Re: Setting the Camera's view to another position?

Post by mickeyjm » Mon Apr 07, 2014 10:38 pm

I have a feeling that in this case it is because the demo Germanunkol posted shifted the camera to positive 250 and you have drawn an object at negative 250. If so just putting a negative sign in front of the 250 in translate() should fix it
Your screen is very zoomed in...

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xFade
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Re: Setting the Camera's view to another position?

Post by xFade » Tue Apr 08, 2014 12:37 am

Here you go and changing the translate to -250 did not work.
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Ragzouken
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Re: Setting the Camera's view to another position?

Post by Ragzouken » Tue Apr 08, 2014 9:35 am

recommend you use the hump library's camera module, it will do all the hard work for you http://vrld.github.io/hump/

Germanunkol
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Re: Setting the Camera's view to another position?

Post by Germanunkol » Tue Apr 08, 2014 3:32 pm

Hi,

Your Main.lua should be named main.lua.
The reason you're not getting any error message is because conf.lua is there, so somehow it seems to load that and then think it's fine. So rename Main.lua to main.lua - at least on linux, I only got a black screen otherwise. Might work on win - since win is not case-sensitive in naming.

About the wrong translation: You need to do two things:
1) Change the -250 to 250 in the Scripts/camera.lua file. What love.graphics.translate does is it simply adds an offset to every following draw call. So If you want an object at -250,0 to be displayed at 0,0 then you need to translate by 250,0 because 250-250 = 0.
2) You're using the love.graphics.pop() function wrong. You need to draw the stuff, before you call the pop() - because pop resets the translation to the state where the push was called - so when you draw things afterwards your translation is no longer active, the way you do it now.
To fix: create a function unsetNewView(), move the love.graphics.pop() call into that and then call that function from love.draw, after drawing the player

Code: Select all

function love.draw()
    setNewView()
    player:draw()
    unsetNewView()
end

...
function setNewView()
    love.graphics.push()
    love.graphics.translate(250, 0)
end

function unsetNewView()
	love.graphics.pop()
end
As a side node: Instead of using .rar, you should make .zip files instead and then rename them to .love before uploading. More people will check out your code when all they have to do is download and run a .love.

Hope this fixes it...
trAInsported - Write AI to control your trains
Bandana (Dev blog) - Platformer featuring an awesome little ninja by Micha and me
GridCars - Our jam entry for LD31
Germanunkol.de

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xFade
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Re: Setting the Camera's view to another position?

Post by xFade » Tue Apr 08, 2014 7:00 pm

Thank you for all the tips, I'm new to love2d so I really appreciate it. :D
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