make the algorithm a bit more customizable

diff --git a/misc/tools/fft-normalmap-to-heightmap.c b/misc/tools/fft-normalmap-to-heightmap.c
index a31b022fca2407f630c12237b87a6e54e50fdd75..909f591ff33667355fec0f52bebdcb5d77ab219d 100644 (file)
--- a/misc/tools/fft-normalmap-to-heightmap.c
+++ b/misc/tools/fft-normalmap-to-heightmap.c
@@ -38,6 +38,8 @@
 void nmap_to_hmap(unsigned char *map, const unsigned char *refmap, int w, int h, double scale, double offset)
 {
        int x, y;
+       int fx, fy;
+       int ffx, ffy;
        double nx, ny, nz;
        double v, vmin, vmax;
 #ifndef C99
@@ -86,23 +88,26 @@ void nmap_to_hmap(unsigned char *map, const unsigned char *refmap, int w, int h,
        for(y = 0; y < h; ++y)
        for(x = 0; x < w; ++x)
        {
-               int fx = x;
-               int fy = y;
+               fx = x;
+               fy = y;
                if(fx > w/2)
                        fx -= w;
                if(fy > h/2)
                        fy -= h;
+               /* these must have the same sign as fx and fy (so ffx*fx + ffy*fy is nonzero), otherwise do not matter */
+               ffx = fx;
+               ffy = fy;
 #ifdef C99
                if(fx||fy)
-                       freqspace1[(w*y+x)] = _Complex_I * (fx * freqspace1[(w*y+x)] + fy * freqspace2[(w*y+x)]) / (fx*fx + fy*fy) / TWO_PI;
+                       freqspace1[(w*y+x)] = _Complex_I * (ffx * freqspace1[(w*y+x)] + ffy * freqspace2[(w*y+x)]) / (ffx*fx + ffy*fy) / TWO_PI;
                else
                        freqspace1[(w*y+x)] = 0;
 #else
                if(fx||fy)
                {
                        save = freqspace1[(w*y+x)][0];
-                       freqspace1[(w*y+x)][0] = -(fx * freqspace1[(w*y+x)][1] + fy * freqspace2[(w*y+x)][1]) / (fx*fx + fy*fy) / TWO_PI;
-                       freqspace1[(w*y+x)][1] =  (fx * save + fy * freqspace2[(w*y+x)][0]) / (fx*fx + fy*fy) / TWO_PI;
+                       freqspace1[(w*y+x)][0] = -(ffx * freqspace1[(w*y+x)][1] + ffy * freqspace2[(w*y+x)][1]) / (ffx*fx + ffy*fy) / TWO_PI;
+                       freqspace1[(w*y+x)][1] =  (ffx * save + ffy * freqspace2[(w*y+x)][0]) / (ffx*fx + ffy*fy) / TWO_PI;
                }
                else
                {