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rotateImage ?

 
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Julu Julu



Joined: 01 Nov 2005
Posts: 9
Location: Germany
PostPosted: Thu Nov 10, 2005 10:02 am    Post subject: rotateImage ? Reply with quote
Hi.

I found this function here.


Code:

function rotateImage(theImage)
   newImage = Image.createEmpty(theImage:height(), theImage:width())
   for x = 1, theImage:width() do
      for y = 1, theImage:height() do
         newImage:blit(y, x, theImage, x, y, 1, 1)
      end
   end
   return newImage
end -- rotateImage



I do not understand this function.
The picture turns always 90 degrees.
How can I turn the picture differently?

For example 50 degrees.
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Zenurb



Joined: 30 Sep 2005
Posts: 106
Location: United Kingdom
PostPosted: Thu Nov 10, 2005 11:24 am    Post subject: Re: rotateImage ? Reply with quote
Julu Julu wrote:
Hi.

I found this function here.


Code:

function rotateImage(theImage)
   newImage = Image.createEmpty(theImage:height(), theImage:width())
   for x = 1, theImage:width() do
      for y = 1, theImage:height() do
         newImage:blit(y, x, theImage, x, y, 1, 1)
      end
   end
   return newImage
end -- rotateImage



I do not understand this function.
The picture turns always 90 degrees.
How can I turn the picture differently?

For example 50 degrees.


You can use sin/cos functions to work out the position of each new pixel.
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Julu Julu



Joined: 01 Nov 2005
Posts: 9
Location: Germany
PostPosted: Thu Nov 10, 2005 1:01 pm    Post subject: Reply with quote
Where I must set sin/cos ?

Code:


function rotateImage(theImage)
   newImage = Image.createEmpty(theImage:height(), theImage:width())
   for x = 1, theImage:width() do
      for y = 1, theImage:height() do



         newImage:blit(   here -> ??? cos , here -> ??? sin   x, theImage, x, y, 1, 1)
      end
   end
   return newImage
end -- rotateImage
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Zenurb



Joined: 30 Sep 2005
Posts: 106
Location: United Kingdom
PostPosted: Thu Nov 10, 2005 1:16 pm    Post subject: Reply with quote
sin and cos are mathematic functions which describe a wave pattern, sine and cosine. cosine is at a 90 degree angle to sine.

here is some code for making something move in a circle (i don't know lua very well)


Code:
x = 130
y = 130
aimage = Image.createEmpty(100, 100)
aimage:print("lol")
while(true)
  screen.clear()
  a = a + 1
  x = x + (sin(a) * 10)
  y = y + (cos(a) * 10)
  screen:blit(x, y, aimage, 0, 0, 100, 100)
end


I think that works but probably not =)

the basic maths will work if you can fix it, to move something in a circle.

the radians value (a) goes from 0 to pi/2+pi (i think) pi=3.14152..etc and you can just divide the highest radian value by 360 then times by the angle you want to find the new position of a singular pixel.
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Julu Julu



Joined: 01 Nov 2005
Posts: 9
Location: Germany
PostPosted: Thu Nov 10, 2005 5:03 pm    Post subject: Reply with quote
Thanks :)
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