support a "reference" image that predefines height for the input textures at given...
authorRudolf Polzer <divVerent@alientrap.org>
Mon, 23 Aug 2010 08:46:29 +0000 (10:46 +0200)
committerRudolf Polzer <divVerent@alientrap.org>
Mon, 23 Aug 2010 08:46:29 +0000 (10:46 +0200)
misc/tools/fft-normalmap-to-heightmap.c

index dc48967f22f9cb8635f894428765658bf30ec624..95782ec83cf1ea8d6175d47496800eb1e7fcafb3 100644 (file)
@@ -35,7 +35,7 @@
 
 #define TWO_PI (4*atan2(1,1) * 2)
 
-void nmap_to_hmap(unsigned char *map, int w, int h, double scale, double offset)
+void nmap_to_hmap(unsigned char *map, const unsigned char *refmap, int w, int h, double scale, double offset)
 {
        int x, y;
        double nx, ny, nz;
@@ -114,7 +114,75 @@ void nmap_to_hmap(unsigned char *map, int w, int h, double scale, double offset)
 
        fftw_execute(f12i1);
 
-       if(scale == 0)
+       if(refmap)
+       {
+               // refmap: a reference map to define the heights
+               // alpha = weight, color = value
+               // if more than one color value is used, colors are also matched
+
+               // we do linear regression, basically
+               // f'(x, y) = f(x, y) * scale + offset
+               // sum((f(x, y) * scale + offset - ref_y(x, y))^2 * ref_a(x, y)) minimize
+
+               // diff by offset:
+               // sum(-2*ref_y(x,y)*ref_a(x,y) + 2*scale*f(x,y)*ref_a(x,y) + 2*offset*ref_a(x,y)) = 0
+               // diff by scale:
+               // sum(-2*f(x,y)*ref_a(x,y) + 2*scale*f(x,y)^2*ref_a(x,y) + 2*offset*f(x,y)*ref_a(x,y)) = 0
+               // ->
+               // offset = (sfa*sfya - sffa*sya) / (sfa*sfa-sa*sffa)
+               // scale  = (sfa*sya - sa*sfya) / (sfa*sfa-sa*sffa)
+
+               double f, a;
+               double o, s;
+               double sa, sfa, sffa, sfva, sva;
+               double mi, ma;
+               sa = sfa = sffa = sfva = sva = 0;
+               mi = 1;
+               ma = -1;
+               for(y = 0; y < h; ++y)
+               for(x = 0; x < w; ++x)
+               {
+                       a = (int)refmap[(w*y+x)*4+0];
+                       v = (map[(w*y+x)*4+0]*0.114 + map[(w*y+x)*4+1]*0.587 + map[(w*y+x)*4+2]*0.299);
+                       v = (v - 128.0) / 127.0; // value 0 is forbidden, 1 -> -1, 255 -> 1
+#ifdef C99
+                       f = creal(imgspace1[(w*y+x)]);
+#else
+                       f = imgspace1[(w*y+x)][0];
+#endif
+                       if(a <= 0)
+                               continue;
+                       if(y < mi)
+                               mi = y;
+                       if(y > ma)
+                               ma = y;
+                       sa += a;
+                       sfa += f*a;
+                       sffa += f*f*a;
+                       sfva += f*v*a;
+                       sva += v*a;
+               }
+               sfa /= (w*h);
+               sffa /= (w*h);
+               sffa /= (w*h);
+               sfva /= (w*h);
+               if(mi < ma)
+               {
+                       o = (sfa*sfva - sffa*sva) / (sfa*sfa-sa*sffa);
+                       s = (sfa*sva - sa*sfva) / (sfa*sfa-sa*sffa);
+               }
+               else // all values of v are equal, so we cannot get scale; we can still get offset
+               {
+                       o = ((sva - sfa) / sa);
+                       s = 1;
+               }
+               // now apply user-given offset and scale to these values
+               // (x * s + o) * scale + offset
+               // x * s * scale + o * scale + offset
+               offset += o * scale;
+               scale *= s;
+       }
+       else if(scale == 0)
        {
 #ifdef C99
                vmin = vmax = creal(imgspace1[0]);
@@ -840,7 +908,7 @@ int Image_WriteTGABGRA (const char *filename, int width, int height, const unsig
 
 int usage(const char *me)
 {
-       printf("Usage: %s <infile_norm.tga> <outfile_normandheight.tga> [<scale> [<offset>]] (get heightmap from normalmap)\n", me);
+       printf("Usage: %s <infile_norm.tga> <outfile_normandheight.tga> [<scale> [<offset> [<infile_ref.tga>]]] (get heightmap from normalmap)\n", me);
        printf("or:    %s <infile_height.tga> <outfile_normandheight.tga> -1 [<scale>] (read from B, Diff)\n", me);
        printf("or:    %s <infile_height.tga> <outfile_normandheight.tga> -2 [<scale>] (read from G, Diff)\n", me);
        printf("or:    %s <infile_height.tga> <outfile_normandheight.tga> -3 [<scale>] (read from R, Diff)\n", me);
@@ -858,10 +926,10 @@ int usage(const char *me)
 
 int main(int argc, char **argv)
 {
-       const char *infile, *outfile;
+       const char *infile, *outfile, *reffile;
        double scale, offset;
-       int nmaplen;
-       unsigned char *nmapdata, *nmap;
+       int nmaplen, w, h;
+       unsigned char *nmapdata, *nmap, *refmap;
 
        if(argc > 1)
                infile = argv[1];
@@ -881,7 +949,12 @@ int main(int argc, char **argv)
        if(argc > 4)
                offset = atof(argv[4]);
        else
-               offset = 0;
+               offset = (scale<0) ? 1 : 0;
+
+       if(argc > 5)
+               reffile = argv[5];
+       else
+               reffile = NULL;
 
        nmapdata = FS_LoadFile(infile, &nmaplen);
        if(!nmapdata)
@@ -896,12 +969,37 @@ int main(int argc, char **argv)
                printf("LoadTGA_BGRA failed\n");
                return 2;
        }
+       w = image_width;
+       h = image_height;
+
+       if(reffile)
+       {
+               nmapdata = FS_LoadFile(infile, &nmaplen);
+               if(!nmapdata)
+               {
+                       printf("FS_LoadFile failed\n");
+                       return 2;
+               }
+               refmap = LoadTGA_BGRA(nmapdata, nmaplen);
+               free(nmapdata);
+               if(!refmap)
+               {
+                       printf("LoadTGA_BGRA failed\n");
+                       return 2;
+               }
+               if(image_width != w || image_height != h)
+               {
+                       printf("reference map must have same size as input normalmap\n");
+                       return 2;
+               }
+       }
+
        if(scale < -6)
                hmap_to_nmap(nmap, image_width, image_height, -scale-7, offset);
        else if(scale < 0)
                hmap_to_nmap_local(nmap, image_width, image_height, -scale-1, offset);
        else
-               nmap_to_hmap(nmap, image_width, image_height, scale, offset);
+               nmap_to_hmap(nmap, refmap, image_width, image_height, scale, offset);
        if(!Image_WriteTGABGRA(outfile, image_width, image_height, nmap))
        {
                printf("Image_WriteTGABGRA failed\n");