First draft of a utility to generate normal maps from a regular texture.

utils/Modeller/Makefile.am

@@ -1,7 +1,10 @@
-noinst_PROGRAMS = threedconvert animassist
+noinst_PROGRAMS = threedconvert animassist normalmap
 
 threedconvert_SOURCES = 3dconvert.cxx
 threedconvert_LDADD = -lplibssg -lplibsg -lplibul $(opengl_LIBS) $(audio_LIBS)
 
 animassist_SOURCES = animassist.c
 animassist_LDADD = $(base_LIBS)
+
+normalmap_SOURCES = normalmap.cxx
+normalmap_LDADD = -lsgscreen $(opengl_LIBS) $(base_LIBS) -lz

utils/Modeller/normalmap.cxx

@@ -0,0 +1,126 @@
+/*
+ * Create normal map textures from regular textures.
+ * Created by: Erik Hofman
+ *
+ * This file is in public domain.
+ */
+
+#include <string.h>
+#include <GL/gl.h>
+#include <simgear/screen/texture.hxx>
+
+
+static float contrast = 1.0;
+static float brightness = 1.0;
+static char *texture_file = NULL, *normalmap_file = NULL;
+static SGTexture texture;
+
+int parse_option(char **args, int n) {
+   char *opt, *arg;
+   int sz, ret=1;
+
+   opt = args[n];
+   if (*(opt+1) == '-')
+      opt++;
+
+   if ((arg = strchr(opt, '=')) != NULL)
+      *arg++ = 0;
+
+   else {
+      ret++;
+      arg = args[n+1];
+   }
+
+   sz = strlen(opt);
+   if (!strncmp(opt, "-help", sz)) {
+      printf("usage:\n  normalmap [-c=contrast] [-b=brightness]");
+      printf(" --t=file [--o=file]\n");
+      exit(0);
+   }
+   if (!strncmp(opt, "-contrast", sz)) {
+      contrast = atof(arg);
+      return ret;
+   }
+   if (!strncmp(opt, "-brightness", sz)) {
+      brightness = atof(arg);
+      return ret;
+   }
+   if (!strncmp(opt, "-texture", sz) ||
+       !strncmp(opt, "-input", sz)) {
+      texture_file = strdup(arg);
+      return ret;
+   }
+   if (!strncmp(opt, "-normalmap", sz) ||
+       !strncmp(opt, "-output", sz)) {
+      normalmap_file = strdup(arg);
+      return ret;
+   }
+
+   return 1;
+}
+
+GLubyte *make_map( GLubyte *data, int width, int height, int colors )
+{
+   GLubyte *map = (GLubyte *)malloc (width * height * 3);
+   
+   for (int y=0; y<height; y++)
+      for (int x=0; x<width; x++)
+      {
+         int mpos = (x + y*width)*3;
+         int dpos = (x + y*width)*colors;
+
+         int xp1 = (x < (width-1)) ? x+1 : 0;
+         int yp1 = (y < (height-1)) ? y+1 : 0;
+         int posxp1 = (xp1 + y*width)*colors;
+         int posyp1 = (x + yp1*width)*colors;
+         
+         map[mpos+0] = (128+(data[posxp1]-data[dpos])/2);
+         map[mpos+1] = (128+(data[posyp1]-data[dpos])/2);
+         map[mpos+2] = 128 + GLubyte(128*brightness);
+      }
+
+   return map;
+}
+
+int main (int argc, char **argv)
+{
+   int i;
+
+   for (i=1; i<argc;)
+      i += parse_option(argv, i);
+
+   if ( !texture_file )
+   {
+      printf("Error: texture file not specified\n");
+      return -1;
+   }
+
+   texture.read_rgb_texture(texture_file);
+   if ( !texture.texture() )
+   {
+      printf("Error: unable to process input file: %s\n", texture_file);
+      printf("       (%s)\n", texture.err_str());
+      return -2;
+   }
+
+   if ( !normalmap_file )
+   {
+      int i;
+      for (i=strlen(texture_file); i>=0; --i)
+         if (texture_file[i] == '.')
+            break;
+
+      normalmap_file = (char *)malloc( i+8 );
+      memcpy(normalmap_file, texture_file, i);
+      memcpy(normalmap_file+i, "_n.rgb\0", 7);
+   }
+
+   // texture.make_grayscale();
+   texture.make_normalmap();
+   texture.write_texture(normalmap_file);
+
+   free( normalmap_file );
+   free( texture_file );
+
+   return 0;
+}