[bsdf] Added essential structures required by the `bsdf' rasterizer.

* src/sdf/ftbsdf.c (*): Added all the essential structures required internally by the
  `bsdf' rasterizer as well as the initializer for the `ED' struct.

src/sdf/ftbsdf.c

@@ -1,3 +1,127 @@
 
+#include <freetype/internal/ftobjs.h>
+#include <freetype/internal/ftdebug.h>
+#include <freetype/internal/ftmemory.h>
+#include <freetype/fttrigon.h>
+
+#include "ftsdf.h"
+#include "ftsdferrs.h"
+#include "ftsdfcommon.h"
+
+  /**************************************************************************
+   *
+   * useful macros
+   *
+   */
+
+  #define ONE 65536 /* 1 in 16.16 */
+
+  /**************************************************************************
+   *
+   * structs
+   *
+   */
+
+  /**************************************************************************
+   *
+   * @Struct:
+   *   BSDF_TRaster
+   *
+   * @Description:
+   *   This struct is used in place of `FT_Raster' and is stored within
+   *   the internal freetype renderer struct. While rasterizing this is
+   *   passed to the `FT_Raster_Render_Func' function, which then can be
+   *   used however we want.
+   *
+   * @Fields:
+   *   memory ::
+   *     Used internally to allocate intermediate memory while raterizing.
+   *
+   */
+  typedef struct  BSDF_TRaster_
+  {
+    FT_Memory  memory;
+
+  } BSDF_TRaster;
+
+  /**************************************************************************
+   *
+   * @Struct:
+   *   ED
+   *
+   * @Description:
+   *   Euclidean distance used for euclidean distance transform can also be
+   *   interpreted as edge distance.
+   *
+   * @Fields:
+   *   dist ::
+   *     Vector length of the `near' parameter. Can be squared or absolute
+   *     depending on the `USE_SQUARED_DISTANCES' parameter defined in
+   *     `ftsdfcommon.h'.
+   *
+   *   near ::
+   *     Vector to the nearest edge. Can also be interpreted as shortest
+   *     distance of a point.
+   *
+   *   alpha ::
+   *     Alpha value of the original bitmap from which we generate SDF.
+   *     While computing the gradient and determining the proper sign
+   *     of a pixel this field is used.
+   *
+   */
+  typedef struct  ED_
+  {
+    FT_16D16      dist;
+    FT_16D16_Vec  near;
+    FT_Byte       alpha;
+
+  } ED;
+
+  /**************************************************************************
+   *
+   * @Struct:
+   *   BSDF_Worker
+   *
+   * @Description:
+   *   Just a convenient struct which is passed to most of the functions
+   *   while generating SDF. This makes it easier to pass parameters because
+   *   most functions require the same parameters.
+   *
+   * @Fields:
+   *   distance_map ::
+   *     A 1D array which is interpreted as 2D array. This array contains
+   *     the Euclidean distance of all the points of the bitmap.
+   *
+   *   width ::
+   *     Width of the above `distance_map'.
+   *     
+   *   rows ::
+   *     Number of rows in the above `distance_map'.
+   *
+   *   params ::
+   *     Internal params and properties required by the rasterizer. See
+   *     `ftsdf.h' for the fields of this struct.
+   *
+   */
+  typedef struct  BSDF_Worker_
+  {
+    ED*                distance_map;
+
+    FT_Int             width;
+    FT_Int             rows;
+
+    SDF_Raster_Params  params;
+
+  } BSDF_Worker;
+
+  /**************************************************************************
+   *
+   * initializer
+   *
+   */
+
+  static
+  const ED  zero_ed = { 0, { 0, 0 }, 0 };
+
 
 /* END */