Skewing a Sprite

[BigKevSexyMan]

How would I go about doing this? Say I wanna take a flat square like this:

_____________
|             |
|             |
|             |
|             |
|             |
|             |
---------------

and turn it into this:

     /|
    / |
   /  |
  |   |
  |   |
  |   |
   \  |
    \ |
     \|

How would I do that?

 

[Roman Candle]

With difficulty. I'm sure there are people working on it, but it's the kind of thing you would normally do with some kind of hardware support. If you really really need to, you would take each colomn as a Rect and stretch blt it onto a new bitmap. Alternatively, you could split each colomn of pixels into a seperate Sprite and use the zoom function on them.

 

[BigKevSexyMan]

I already figured I could do the last suggestion, but I think that would cause to much lag. How would I do the first thing you mentioned?

 

[rpgmaker]

Just mess with the zoom_x and zoom_y and you can get that effect

 

[Joe parz]

you want to skew a sprite correct, because you could that in MS paint.

 

[BigKevSexyMan]

No, I have to do this in RGSS.

 

[Japa]

there is a script that does this, It is is lost in the bowels of the server, and needs heavy modification, if you are up to it.

here it is: http://www.letsshareit.net/files/2/Mode7 Test.rar

some say they get a 404 error, but I don't.

 

[SephirothSpawn]

Just treat it pixel by pixel. A little math you could do it fairly easily.

I suggest making a dump bitmap and just use rectangle blt transfers. You just have to go about it logically (and possibly some trig)

You can see in this method that I used in the Shift Puzzle's Game:

#==============================================================================
# ** Bitmap
#==============================================================================

class Bitmap
  #--------------------------------------------------------------------------
  # * Rotate Square 90 Degree Increments
  #--------------------------------------------------------------------------
  def sqr_rotate_90(degrees = 90)
    # If Degrees is Greater than 360
    degrees -= 360 until degrees < 360
    # If Degrees is Less than 0
    degress += 360 until degrees >= 0
    # Duplicates Self
    dummy = self.dup
    # Passes Through all Pixels on Dummy Bitmap
    for i in 0...self.height
      for j in 0...self.width
        # Configures destination Pixel Coordinates
        case degrees
        when 90  ; x, y = width - i - 1, j
        when 180 ; x, y = width - j - 1, height - i - 1
        when 270 ; x, y = i, height - j - 1
        else     ; return
        end
        # Reset Pixel
        self.set_pixel(x, y, dummy.get_pixel(j, i))
      end
    end
  end
end

This actually works pixel by pixel, but it starts with making a dummy bitmap and transfering pixels that route.

What you need is something that will stretch_blt.

http://img139.imageshack.us/img139/9195/examplegk4.png[/img]

That is essentially all you are doing. Just start from the left of your actual bitmap and move right, stretching the bitmap to fit that area.

If you need an example, I can work up something (maybe even a method of doing something like this.

 

[BigKevSexyMan]

Hmmm.....when I use that script it lags.

 

[Kest]

This request is for your first person RPG script?

 

[BigKevSexyMan]

Yeah, I tried to do some sort of tiling thing, but the result was ugly, so the only choice I have is to skew it. Maybe if I go by columns instead of pixels, that might speed things up.