Add new module for distance field generation.

third_party/edtaa/edtaa3.h

-/* 
- Permission is hereby granted, free of charge, to any person obtaining a copy
- of this software and associated documentation files (the "Software"), to deal
- in the Software without restriction, including without limitation the rights
- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- copies of the Software, and to permit persons to whom the Software is
- furnished to do so, subject to the following conditions:
-
- The above copyright notice and this permission notice shall be included in
- all copies or substantial portions of the Software.
-
- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- THE SOFTWARE.
- */
-
-#define EDTAA_UNSIGNED_CHAR_INPUT 1
-
-namespace EDTAA {
-
-#if EDTAA_UNSIGNED_CHAR_INPUT
-typedef unsigned char EdtaaImageType;
-#else
-typedef double EdtaaImageType;
-#endif
-
-void computegradient(EdtaaImageType *img, int w, int h, double *gx, double *gy);
-void edtaa3(EdtaaImageType *img, double *gx, double *gy, int w, int h, 
-                   short *distx, short *disty, double *dist);
-
-}