1 files changed, 122 insertions, 0 deletions
diff --git a/plug-ins/gimpressionist/plasma.c b/plug-ins/gimpressionist/plasma.c
new file mode 100644
index 0000000..82f9212
--- /dev/null
+++ b/plug-ins/gimpressionist/plasma.c
@@ -0,0 +1,122 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <gtk/gtk.h>
+
+#include <libgimpmath/gimpmath.h>
+#include <libgimp/gimp.h>
+
+#include "gimpressionist.h"
+#include "ppmtool.h"
+#include "random.h"
+
+static int
+pfix (int n)
+{
+  if (n < 1) return 1;
+  if (n > 255) return 255;
+  return n;
+}
+
+#define PIXEL(y,x,z) p->col[(y) * rowstride + (x) * 3 + z]
+
+static void
+mkplasma_sub (ppm_t *p, int x1, int x2, int y1, int y2, float turb)
+{
+  int rowstride = p->width * 3;
+  int r=0;
+  int xr, yr, nx, ny;
+
+  xr = abs (x1 - x2);
+  yr = abs (y1 - y2);
+
+  if ((xr == 0) && (yr == 0))
+    return;
+
+  nx = (x1 + x2)/2;
+  ny = (y1 + y2)/2;
+  if (!PIXEL (y1,nx,r))
+    PIXEL (y1, nx, r) = pfix ((PIXEL (y1, x1, r) + PIXEL (y1, x2, r)) / 2.0 +
+                              turb * g_rand_double_range (random_generator,
+                                                          -xr / 2.0,
+                                                           xr / 2.0));
+  if (!PIXEL (y2, nx, r))
+    PIXEL (y2, nx, r) = pfix ((PIXEL (y2, x1, r) + PIXEL (y2, x2, r)) / 2.0 +
+                              turb * g_rand_double_range (random_generator,
+                                                          -xr / 2.0,
+                                                           xr / 2.0));
+  if (!PIXEL (ny, x1, r))
+    PIXEL (ny, x1, r) = pfix ((PIXEL (y1, x1, r)+PIXEL (y2, x1, r)) / 2.0 +
+                              turb * g_rand_double_range (random_generator,
+                                                          -yr / 2.0,
+                                                           yr / 2.0));
+  if (!PIXEL (ny, x2, r))
+    PIXEL (ny, x2, r) = pfix ((PIXEL (y1, x2, r) + PIXEL (y2, x2, r)) / 2.0 +
+                              turb * g_rand_double_range (random_generator,
+                                                          -yr / 2.0,
+                                                           yr / 2.0));
+  if (!PIXEL (ny, nx, r))
+    PIXEL (ny, nx, r) =
+      pfix ((PIXEL (y1, x1, r) + PIXEL (y1, x2, r) +
+             PIXEL (y2, x1, r) + PIXEL( y2, x2, r)) / 4.0 +
+            turb * g_rand_double_range (random_generator,
+                                        -(xr + yr)/4.0,
+                                         (xr + yr)/4.0));
+
+  if (xr>1)
+    {
+      mkplasma_sub (p, x1, nx, y1, ny, turb);
+      mkplasma_sub (p, nx, x2, y1, ny, turb);
+    }
+  if (yr>1)
+    {
+      mkplasma_sub (p, x1, nx, ny, y2, turb);
+      mkplasma_sub (p, nx, x2, ny, y2, turb);
+    }
+}
+
+static void
+mkplasma_red (ppm_t *p, float turb)
+{
+  int x = 0, y = 0;
+  int rowstride = p->width * 3;
+
+  for (x = 0; x < p->width; x++)
+    for (y = 0; y < p->height; y++)
+      PIXEL (y, x, 0) = 0;
+  x--; y--;
+  PIXEL (0, 0, 0) = g_rand_int_range (random_generator, 1, 256);
+  PIXEL (y, 0, 0) = g_rand_int_range (random_generator, 1, 256);
+  PIXEL (0, x, 0) = g_rand_int_range (random_generator, 1, 256);
+  PIXEL (y, x, 0) = g_rand_int_range (random_generator, 1, 256);
+  mkplasma_sub (p, 0, x, 0, y, turb);
+}
+
+void
+mkgrayplasma (ppm_t *p, float turb)
+{
+  int y, l;
+
+  mkplasma_red (p, turb);
+  l = p->width * 3 * p->height;
+  for (y = 0; y < l; y += 3)
+    p->col[y+1] = p->col[y+2] = p->col[y];
+}