Rotating a image

could you post a little sample code I am having trouble following what you are saying.

pls I really need help. somebody pls help me pls?

What you probably should do is check out some docs on texture mapping. You can make a simple texturemapper and use then just rotate the polygon''s points.

Just do a google search on "programminf texture mapping"...

It's really easy, if you only want to restrict it to 2D.

In your original algorithm, you took each source pixel, applied a 2D rotation formula to find it's new position, and draw it there. Because of inaccuracies and the discrete nature of pixel graphics, you'll get holes/overlapping pixels.

Just turn the approach around: for every pixel in the destination image, rotate it *backwards* (using the same equation as you did before, just with a negative angle) and find it's position in the source image. Then copy this source pixel to the destination one.

Pseudocode:

for( y=0; y<height; y++ ) {
   for( x=0; x<width; x++ ) {

      // x and y are destination coordinates, so rotate them 
      // backwards into the source image
      RotatePixel(x, y, -angle, &source_x, &source_y);

      // source_x/y now hold the position of the destination
      // pixel in the source image. Now, just copy it:
      Destination_array[x][y] = Source_array[source_x, source_y];

   }
}
  

As said, RotatePixel() is the same equation as you currently use. The only difference is the negative angle.

/ Yann

[edited by - Yann L on September 27, 2002 2:44:00 PM]