[gegl] workshop: add spiral operation

[N/A <ell src gnome org>]

commit 95573de6103ea0a7126260d3fa6fc4f7c5a18dd8
Author: Ell <ell_se yahoo com>
Date:   Mon Apr 17 20:14:56 2017 -0400

    workshop: add spiral operation
    
    It, er, renders a spiral.  You're feeling dizzy...

 operations/workshop/Makefile.am |    3 +-
 operations/workshop/spiral.c    |  245 +++++++++++++++++++++++++++++++++++++++
 po/POTFILES.in                  |    1 +
 3 files changed, 248 insertions(+), 1 deletions(-)
---
diff --git a/operations/workshop/Makefile.am b/operations/workshop/Makefile.am
index e190b1d..008412d 100644
--- a/operations/workshop/Makefile.am
+++ b/operations/workshop/Makefile.am
@@ -27,4 +27,5 @@ op_LTLIBRARIES =    \
        rawbayer-load.la \
        segment-kmeans.la \
        shadows-highlights.la \
-       shadows-highlights-correction.la
+       shadows-highlights-correction.la \
+       spiral.la
diff --git a/operations/workshop/spiral.c b/operations/workshop/spiral.c
new file mode 100644
index 0000000..1d5bbe1
--- /dev/null
+++ b/operations/workshop/spiral.c
@@ -0,0 +1,245 @@
+/* This file is an image processing operation for GEGL
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (C) 2017 Ell
+ *
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+
+#ifdef GEGL_PROPERTIES
+
+property_double (x, _("X"), 0.5)
+  description (_("Spiral origin X coordinate"))
+  ui_range    (0.0, 1.0)
+  ui_meta     ("unit", "relative-coordinate")
+  ui_meta     ("axis", "x")
+
+property_double (y, _("Y"), 0.5)
+  description (_("Spiral origin Y coordinate"))
+  ui_range    (0.0, 1.0)
+  ui_meta     ("unit", "relative-coordinate")
+  ui_meta     ("axis", "y")
+
+property_double (radius, _("Radius"), 100.0)
+  description (_("Spiral radius"))
+  value_range (1.0, G_MAXDOUBLE)
+  ui_range    (1.0, 400.0)
+  ui_meta     ("unit", "pixel-distance")
+
+property_double (thickness, _("Thickness"), 0.5)
+  description (_("Spiral thickness, as a fraction of the radius"))
+  value_range (0.0, 1.0)
+
+property_double (angle, _("Angle"), 0.0)
+  description (_("Spiral start angle"))
+  value_range (0.0, 360.0)
+  ui_meta     ("unit", "degree")
+
+property_boolean (clockwise, _("Clockwise"), TRUE)
+  description (_("Expand spiral clockwise"))
+
+property_color  (color1, _("Color 1"), "black")
+  ui_meta     ("role", "color-primary")
+
+property_color  (color2, _("Color 2"), "white")
+  ui_meta     ("role", "color-secondary")
+
+property_int    (width, _("Width"), 1024)
+  description (_("Width of the generated buffer"))
+  value_range (0, G_MAXINT)
+  ui_range    (0, 4096)
+  ui_meta     ("unit", "pixel-distance")
+  ui_meta     ("axis", "x")
+  ui_meta     ("role", "output-extent")
+
+property_int    (height, _("Height"), 768)
+  description (_("Height of the generated buffer"))
+  value_range (0, G_MAXINT)
+  ui_range    (0, 4096)
+  ui_meta     ("unit", "pixel-distance")
+  ui_meta     ("axis", "y")
+  ui_meta     ("role", "output-extent")
+
+#else
+
+#define GEGL_OP_POINT_RENDER
+#define GEGL_OP_NAME     spiral
+#define GEGL_OP_C_SOURCE spiral.c
+
+#include "gegl-op.h"
+#include <math.h>
+
+static inline gdouble
+odd_pow (gdouble base,
+         gdouble exponent)
+{
+  if (base >= 0.0)
+    return  pow ( base, exponent);
+  else
+    return -pow (-base, exponent);
+}
+
+static void
+prepare (GeglOperation *operation)
+{
+  gegl_operation_set_format (operation, "output", babl_format ("R'G'B'A float"));
+}
+
+static GeglRectangle
+get_bounding_box (GeglOperation *operation)
+{
+  return gegl_rectangle_infinite_plane ();
+}
+
+static inline void
+blend (const gfloat *color1,
+       const gfloat *color2,
+       gfloat        a,
+       gfloat       *result)
+{
+  if (a == 0.0)
+    {
+      memcpy (result, color1, 4 * sizeof (gfloat));
+    }
+  else if (a == 1.0)
+    {
+      memcpy (result, color2, 4 * sizeof (gfloat));
+    }
+  else
+    {
+      gfloat alpha = color1[3] + a * (color2[3] - color1[3]);
+      gint   c;
+
+      if (alpha)
+        {
+          gfloat ratio = a * color2[3] / alpha;
+
+          for (c = 0; c < 3; c++)
+            result[c] = color1[c] + ratio * (color2[c] - color1[c]);
+        }
+      else
+        {
+          memcpy (result, color1, 3 * sizeof (gfloat));
+        }
+
+      result[3] = alpha;
+    }
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         void                *out_buf,
+         glong                n_pixels,
+         const GeglRectangle *roi,
+         gint                 level)
+{
+  GeglProperties      *o         = GEGL_PROPERTIES (operation);
+  const Babl          *format    = babl_format ("R'G'B'A float");
+  gfloat              *dest      = out_buf;
+  gdouble              radius    = o->radius;
+  gdouble              lim       = radius * o->thickness;
+  gdouble              angle     = G_PI * o->angle / 180.0;
+  gboolean             clockwise = o->clockwise;
+  gfloat               color1[4];
+  gfloat               color2[4];
+  gdouble              x0;
+  gdouble              x;
+  gdouble              y;
+  gint                 i;
+  gint                 j;
+
+  gegl_color_get_pixel (o->color1, format, color1);
+  gegl_color_get_pixel (o->color2, format, color2);
+
+  if (radius == 1.0 || o->thickness == 0.0 || o->thickness == 1.0)
+    {
+      gfloat color[4];
+
+      blend (color2, color1, o->thickness, color);
+
+      gegl_memset_pattern (dest, color, sizeof (color), n_pixels);
+
+      return TRUE;
+    }
+
+  if (clockwise)
+    angle = G_PI - angle;
+
+  angle += 2 * G_PI;
+
+  x0 = roi->x - gegl_coordinate_relative_to_pixel (o->x, o->width);
+  y  = roi->y - gegl_coordinate_relative_to_pixel (o->y, o->height);
+
+  for (j = roi->height; j; j--, y++)
+    {
+      gdouble y2 = y * y;
+
+      x = x0;
+
+      for (i = roi->width; i; i--, x++)
+        {
+          gdouble x2 = x * x;
+          gdouble r  = sqrt (x2 + y2);
+          gdouble t  = atan2 (y, clockwise ? -x : x) + angle;
+          gdouble a;
+          gdouble l;
+
+          l = fmod (r + radius * t / (2.0 * G_PI), radius);
+
+          if (l < 0.5)
+            a = MIN (lim, l + 0.5) + MAX (lim - (radius + l - 0.5), 0.0);
+          else if (l > radius - 0.5)
+            a = MAX (lim - l + 0.5, 0.0) + MIN (lim, l + 0.5 - radius);
+          else
+            a = CLAMP (lim - l + 0.5, 0.0, 1.0);
+
+          blend (color2, color1, a, dest);
+
+          dest += 4;
+        }
+    }
+
+  return TRUE;
+}
+
+static void
+gegl_op_class_init (GeglOpClass *klass)
+{
+  GeglOperationClass            *operation_class;
+  GeglOperationPointRenderClass *point_render_class;
+
+  operation_class    = GEGL_OPERATION_CLASS (klass);
+  point_render_class = GEGL_OPERATION_POINT_RENDER_CLASS (klass);
+
+  point_render_class->process = process;
+
+  operation_class->get_bounding_box = get_bounding_box;
+  operation_class->prepare = prepare;
+  operation_class->opencl_support = FALSE;
+
+  gegl_operation_class_set_keys (operation_class,
+    "name",               "gegl:spiral",
+    "title",              _("Spiral"),
+    "categories",         "render",
+    "position-dependent", "true",
+    "license",            "GPL3+",
+    "description",        _("Spiral renderer"),
+    NULL);
+}
+
+#endif
diff --git a/po/POTFILES.in b/po/POTFILES.in
index fae2756..6604981 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -252,3 +252,4 @@ operations/workshop/rawbayer-load.c
 operations/workshop/segment-kmeans.c
 operations/workshop/shadows-highlights.c
 operations/workshop/shadows-highlights-correction.c
+operations/workshop/spiral.c