[gegl/soc-2011-ops] Added the emboss op

[Robert Sasu <sasurobert src gnome org>]

commit df3ae5ea0ae66894e5ecbc73ba1806f9dc97504b
Author: Robert Sasu <sasu robert gmail com>
Date:   Mon Jun 20 15:02:59 2011 +0300

    Added the emboss op

 operations/workshop/emboss.c |  250 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 250 insertions(+), 0 deletions(-)
---
diff --git a/operations/workshop/emboss.c b/operations/workshop/emboss.c
new file mode 100644
index 0000000..066ff57
--- /dev/null
+++ b/operations/workshop/emboss.c
@@ -0,0 +1,250 @@
+/* This file is an image processing operation for GEGL
+ *
+ * GEGL is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * GEGL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with GEGL; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Algorithm 1997 Eric L. Hernes (erich rrnet com)
+ * Copyright 2011 Robert Sasu (sasu robert gmail com)
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_double (azimuth, _("Azimuth"), 0.0, 360.0, 30.0,
+                   _("The value of azimuth"))
+gegl_chant_double (elevation, _("Elevation"), 0.0, 180.0, 45.0,
+                   _("The value of elevation"))
+gegl_chant_int    (depth, _("Depth"), 1, 100, 20,
+                   _("Pixel depth"))
+gegl_chant_string (filter, _("Filter"), "emboss",
+                   _("Optional parameter to override automatic selection "
+                     "of emboss filter. Choices are emboss, blur-map"))
+
+#else
+
+#define GEGL_CHANT_TYPE_AREA_FILTER
+#define GEGL_CHANT_C_FILE        "emboss.c"
+
+#include "gegl-chant.h"
+#include <math.h>
+#include <stdio.h>
+
+#define DEG_TO_RAD(d) (((d) * G_PI) / 180.0)
+
+/*
+ * ANSI C code from the article
+ * "Fast Embossing Effects on Raster Image Data"
+ * by John Schlag, jfs kerner com
+ * in "Graphics Gems IV", Academic Press, 1994
+ *
+ * Emboss - shade 24-bit pixels using a single distant light source.
+ * Normals are obtained by differentiating a monochrome 'bump' image.
+ * The unary case ('texture' == NULL) uses the shading result as output.
+ * The binary case multiples the optional 'texture' image by the shade.
+ * Images are in row major order with interleaved color components
+ * (rgbrgb...).  E.g., component c of pixel x,y of 'dst' is
+ * dst[3*(y*width + x) + c].
+ */
+
+static void
+emboss (gfloat              *src_buf,
+        const GeglRectangle *src_rect,
+        gfloat              *dst_buf,
+        const GeglRectangle *dst_rect,
+        gint                 x,
+        gchar               *text,
+        gint                 floats_per_pixel,
+        gint                 alpha,
+        gdouble              azimuth,
+        gdouble              elevation,
+        gint                 width45)
+{
+  gint y;
+  gint offset, verify;
+  gint bytes;
+
+  gdouble Lx, Ly, Lz;
+  gdouble Nz, Nz2, NzLz;
+
+  Lx = cos (azimuth) * cos (elevation);
+  Ly = sin (azimuth) * cos (elevation);
+  Lz = sin (elevation);
+  Nz = 1.0 / width45;
+  Nz2  = Nz * Nz;
+  NzLz = Nz * Lz;
+
+  bytes = (alpha) ? floats_per_pixel - 1 : floats_per_pixel;
+
+  verify = src_rect->width * src_rect->height * floats_per_pixel;
+  offset = x * dst_rect->width * floats_per_pixel;
+
+  for (y = 0; y < dst_rect->width; y++)
+    {
+      gint   i, j, b, count;
+      gfloat Nx, Ny, NdotL;
+      gfloat shade;
+      gfloat M[3][3];
+      gfloat a;
+
+      for (i = 0; i < 3; i++)
+        for (j = 0; j < 3; j++)
+          M[i][j] = 0.0;
+
+      for (b = 0; b < bytes; b++)
+        for (i = 0; i < 3; i++)
+          for (j = 0; j < 3; j++)
+            {
+              count = ((x+i-1)*src_rect->width + (y+j-1))*floats_per_pixel + bytes;
+
+              /*verify each time that we are in the source image*/
+              if (alpha && count >= 0 && count < verify)
+                a = src_buf[count];
+              else
+                a = 1.0;
+
+              /*calculate recalculate the sorrounding pixels by multiplication*/
+              /*after we have that we can calculate new value of the pixel*/
+              if ((count - bytes + b) >= 0 && (count - bytes + b) < verify)
+                M[i][j] += a * src_buf[count - bytes + b];
+            }
+
+      Nx = M[0][0] + M[1][0] + M[2][0] - M[0][2] - M[1][2] - M[2][2];
+      Ny = M[2][0] + M[2][1] + M[2][2] - M[0][0] - M[0][1] - M[0][2];
+
+      /*calculating the shading result (same as in gimp)*/
+      if ( Nx == 0 && Ny == 0 )
+        shade = Lz;
+      else if ( (NdotL = Nx * Lx + Ny * Ly + NzLz) < 0 )
+        shade = 0;
+      else
+        shade = NdotL / sqrt(Nx*Nx + Ny*Ny + Nz2);
+
+      count = (x*src_rect->width + y)*floats_per_pixel;
+
+      /*setting the value of the destination buffer*/
+      if (bytes == 1)
+        dst_buf[offset++] = shade;
+      else
+        {
+          /*recalculating every byte of a pixel*/
+          /*by multiplying with the shading result*/
+
+          for (b = 0; b < bytes; b++)
+            if ((count + b) >= 0 && (count + b) < verify)
+              dst_buf[offset++] = (src_buf[count+b] * shade) ;
+            else
+              dst_buf[offset++] = 1.0;
+
+          /*preserving alpha*/
+          if (alpha && (count + bytes) >= 0 && (count + bytes) < verify)
+            dst_buf[offset++] = src_buf[count + bytes];
+          else
+            dst_buf[offset++] = 1.0 ;
+        }
+    }
+}
+
+static void
+prepare (GeglOperation *operation)
+{
+  GeglChantO              *o       = GEGL_CHANT_PROPERTIES (operation);
+  GeglOperationAreaFilter *op_area = GEGL_OPERATION_AREA_FILTER (operation);
+
+  op_area->left = op_area->right = op_area->top = op_area->bottom = 3;
+
+  if (o->filter && !strcmp(o->filter, "blur-map"))
+    gegl_operation_set_format (operation, "output",
+			       babl_format ("RGBA float"));
+  else
+    gegl_operation_set_format (operation, "output",
+			       babl_format ("Y float"));
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *result)
+{
+  GeglChantO              *o       = GEGL_CHANT_PROPERTIES (operation);
+  GeglOperationAreaFilter *op_area = GEGL_OPERATION_AREA_FILTER (operation);
+
+  GeglRectangle  rect;
+  gfloat        *src_buf;
+  gfloat        *dst_buf;
+
+  gchar         *type;
+  gint           alpha;
+  gint           x;
+  gint           floats_per_pixel;
+
+  /*blur-map or emboss*/
+  if (o->filter && !strcmp (o->filter, "blur-map"))
+    {
+      type = "RGBA float";
+      floats_per_pixel = 4;
+      alpha = 1;
+    }
+  else
+    {
+      type = "Y float";
+      floats_per_pixel = 1;
+      alpha = 0;
+    }
+
+  rect.x      = result->x - op_area->left;
+  rect.width  = result->width + op_area->left + op_area->right;
+  rect.y      = result->y - op_area->top;
+  rect.height = result->height + op_area->top + op_area->bottom;
+
+  src_buf = g_new0 (gfloat, rect.width * rect.height * floats_per_pixel);
+  dst_buf = g_new0 (gfloat, rect.width * rect.height * floats_per_pixel);
+
+  gegl_buffer_get (input, 1.0, &rect, babl_format (type),
+                   src_buf, GEGL_AUTO_ROWSTRIDE);
+
+  /*do for every row*/
+  for (x = 0; x < rect.height; x++)
+    emboss (src_buf, &rect, dst_buf, &rect, x, type, floats_per_pixel, alpha,
+	    DEG_TO_RAD (o->azimuth), DEG_TO_RAD (o->elevation), o->depth);
+
+  gegl_buffer_set (output, &rect, babl_format (type),
+                   dst_buf, GEGL_AUTO_ROWSTRIDE);
+
+  g_free (src_buf);
+  g_free (dst_buf);
+
+  return TRUE;
+}
+
+static void
+gegl_chant_class_init (GeglChantClass *klass)
+{
+  GeglOperationClass       *operation_class;
+  GeglOperationFilterClass *filter_class;
+
+  operation_class = GEGL_OPERATION_CLASS (klass);
+  filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
+
+  filter_class->process    = process;
+  operation_class->prepare = prepare;
+
+  operation_class->categories  = "distort";
+  operation_class->name        = "gegl:emboss";
+  operation_class->description =
+    _("Simulates an image created by embossing.");
+}
+
+#endif