[Wolves] rotate 2d array by 45degrees

[Andrew Lewis]

Andrew Lewis wrote:

> Andrew Lewis wrote:
>
>>> I was looking for a generic algorthim but I can't find any that seem 
>>> to work the way I want.  I guess it;s numeric time
>>>   
>>
This should be of some help. for the x,y co-ords of your grid:

where T is 0.5*(total width of the matrix)
X = new x position
Y = new y position

X = ((x-T) * cos(45)) - ((y-T) * sin(45))
Y = ((y-T) * cos(45)) + ((x-T) * sin(45))

I think the size of the new matrix needs to be at least 2T-1 if the 
source is odd and square, but it's late and I'm tired so I could be 
wrong (again)
This is broadly the right way to do it i think. The problem is that the 
array data will be interspersed will null data because of the way the 
co-ordinate system works. A leaner way might be to use a list rather 
than an array, and pump the data in diagonally from the source table. 
This would only work for 45 deg but would be faster and waste less 
memory than a general formula like the one above.

spline