[gegl] add a waves operator, ported from the legagy gimp plugin

[Michael Murà <mmure src gnome org>]

commit a45f5bd395a81d1b52d63e2fbe3f3f9f77139692
Author: Audrey Mandet <mandet audrey gmail com>
Date:   Sun Sep 18 19:51:50 2011 +0200

    add a waves operator, ported from the legagy gimp plugin

 operations/workshop/waves.c |  165 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 165 insertions(+), 0 deletions(-)
---
diff --git a/operations/workshop/waves.c b/operations/workshop/waves.c
new file mode 100644
index 0000000..8712c23
--- /dev/null
+++ b/operations/workshop/waves.c
@@ -0,0 +1,165 @@
+/* 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/>.
+ *
+ * Copyright 2011 Audrey Mandet <mandet audrey gmail com>
+ * Copyright (c) 1997 Eric L. Hernes (erich rrnet com)
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_double (x, _("X"), -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
+                   _("X coordinate of the center of the waves"))
+
+gegl_chant_double (y, _("Y"), -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
+                   _("Coordinate y of the center of the waves"))
+
+gegl_chant_double (amplitude, _("Amplitude"), 0.0, 1000.0, 25.0,
+                   _("Amplitude of the ripple"))
+
+gegl_chant_double (period, _("Period"), 0.0, 1000.0, 200.0,
+                   _("Period of the ripple"))
+
+gegl_chant_double (phi, _("Phase shift"), -1.0, 1.0, 0.0,
+                   _("Phase shift"))
+
+gegl_chant_enum (sampler_type, _("Sampler"), GeglSamplerType, GEGL_TYPE_SAMPLER_TYPE,
+                 GEGL_SAMPLER_CUBIC, _("Sampler used internally"))
+
+
+#else
+
+#define GEGL_CHANT_TYPE_AREA_FILTER
+#define GEGL_CHANT_C_FILE       "waves.c"
+
+#include "gegl-chant.h"
+#include <stdio.h>
+#include <math.h>
+
+static void prepare (GeglOperation *operation)
+{
+  GeglChantO              *o;
+  GeglOperationAreaFilter *op_area;
+
+  op_area = GEGL_OPERATION_AREA_FILTER (operation);
+  o       = GEGL_CHANT_PROPERTIES (operation);
+
+  op_area->left   = o->amplitude;
+  op_area->right  = o->amplitude;
+  op_area->top    = o->amplitude;
+  op_area->bottom = o->amplitude;
+
+  gegl_operation_set_format (operation, "input",
+                             babl_format ("RGBA float"));
+  gegl_operation_set_format (operation, "output",
+                             babl_format ("RGBA float"));
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *result)
+{
+  GeglChantO *o                    = GEGL_CHANT_PROPERTIES (operation);
+
+  gint x = result->x; /* initial x                   */
+  gint y = result->y; /*           and y coordinates */
+
+  gfloat *dst_buf = g_slice_alloc (result->width * result->height * 4 * sizeof(gfloat));
+
+  gfloat *out_pixel = dst_buf;
+
+  GeglSampler *sampler = gegl_buffer_sampler_new (input,
+                                                  babl_format ("RGBA float"),
+                                                  o->sampler_type);
+
+  gint n_pixels = result->width * result->height;
+
+  while (n_pixels--)
+    {
+      gdouble coordsx = 0.0;
+      gdouble coordsy = 0.0;
+      gdouble radius = 0.0;
+      gdouble shift = 0.0;
+      gdouble ux = 0.0; /* unit vector of the radius */
+      gdouble uy = 0.0;
+      gdouble vx = 0.0; /* orthogonal vector of u */
+      gdouble vy = 0.0;
+      gdouble dx = 0.0;
+      gdouble dy = 0.0;
+
+      dx = (gdouble)x-o->x;
+      dy = (gdouble)y-o->y;
+
+      radius = sqrt( dx * dx + dy * dy );
+      shift = o->amplitude * sin(2.0 * G_PI * radius / o->period + 2.0 * G_PI * o->phi);
+
+      ux = dx / radius;
+      uy = dy / radius;
+      vx = -uy;
+      vy = ux;
+
+      coordsx = x + shift * vx;
+      coordsy = y + shift * vy;
+
+
+      gegl_sampler_get (sampler,
+                        coordsx,
+                        coordsy,
+                        NULL,
+                        out_pixel);
+
+      out_pixel += 4;
+
+      /* update x and y coordinates */
+      x++;
+      if (x>=result->x + result->width)
+        {
+          x=result->x;
+          y++;
+        }
+    }
+
+  gegl_buffer_set (output, result, babl_format ("RGBA float"), dst_buf, GEGL_AUTO_ROWSTRIDE);
+  g_slice_free1 (result->width * result->height * 4 * sizeof(gfloat), dst_buf);
+
+  g_object_unref (sampler);
+
+  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:waves";
+  operation_class->description = _("Transform the buffer with waves");
+}
+
+#endif