[gegl] plasma: don't use a sampler + fix + speedup

[N/A <ell src gnome org>]

commit fa702369ad30bafe82a86b171776e3e24a276675
Author: Ell <ell_se yahoo com>
Date:   Mon May 14 02:47:14 2018 -0400

    plasma: don't use a sampler + fix + speedup
    
    gegl:plasma uses a sampler, created at the start of the operation,
    to sample the output buffer, after having written to it.  This
    should be avoided, since the sampler may return outdated cached
    data (at least in theory).  Use gegl_buffer_get() instead.
    
    When the subdivided region is small enough, the op switches to use
    a linear buffer, instead of directly using the output buffer, to
    speed processing up.  However, the op only writes to the linear
    buffer, while still reading from the output buffer, which both
    produces (subtly) wrong results, and is slower than necessary.  Fix
    this by reading from the linear buffer, when in use.
    
    Update reference hash.

 operations/common-gpl3+/plasma.c |   66 +++++++++++++++++++++++++++-----------
 1 files changed, 47 insertions(+), 19 deletions(-)
---
diff --git a/operations/common-gpl3+/plasma.c b/operations/common-gpl3+/plasma.c
index c7026af..8b43a50 100644
--- a/operations/common-gpl3+/plasma.c
+++ b/operations/common-gpl3+/plasma.c
@@ -82,7 +82,6 @@ property_seed (seed, _("Random seed"), rand)
 typedef struct
 {
   GeglBuffer     *output;
-  GeglSampler    *sampler;
   GRand          *gr;
   GeglProperties *o;
   float          *buffer;
@@ -132,6 +131,40 @@ add_random (GRand  *gr,
 }
 
 static void
+get_pixel (PlasmaContext *context,
+           gfloat        *pixel,
+           gint           x,
+           gint           y)
+{
+  if (G_UNLIKELY (!context->using_buffer))
+    {
+      GeglRectangle rect;
+
+      rect.x = x;
+      rect.y = y;
+      rect.width = 1;
+      rect.height = 1;
+
+      gegl_buffer_get (context->output, &rect, 1.0, NULL /* R'G'B' float */,
+                       pixel, GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+    }
+  else
+    {
+      float *ptr;
+      gint index;
+
+      index = ((y - context->buffer_y) * context->buffer_width +
+               x - context->buffer_x);
+
+      ptr = context->buffer + index * 3;
+
+      *pixel++ = *ptr++;
+      *pixel++ = *ptr++;
+      *pixel++ = *ptr++;
+    }
+}
+
+static void
 put_pixel (PlasmaContext *context,
            gfloat        *pixel,
            gint           x,
@@ -148,7 +181,6 @@ put_pixel (PlasmaContext *context,
 
       gegl_buffer_set (context->output, &rect, 0, NULL /* R'G'B' float */,
                        pixel, GEGL_AUTO_ROWSTRIDE);
-      return;
     }
   else
     {
@@ -173,8 +205,7 @@ do_plasma (PlasmaContext *context,
            gint           x2,
            gint           y2,
            gint           plasma_depth,
-           gint           recursion_depth,
-           gint           level)
+           gint           recursion_depth)
 {
   gfloat tl[3], ml[3], bl[3], mt[3], mm[3], mb[3], tr[3], mr[3], br[3];
   gfloat tmp[3];
@@ -201,7 +232,7 @@ do_plasma (PlasmaContext *context,
       context->buffer_y = y1;
       context->buffer_width = x2 - x1 + 1;
 
-      ret = do_plasma (context, x1, y1, x2, y2, plasma_depth, recursion_depth, level);
+      ret = do_plasma (context, x1, y1, x2, y2, plasma_depth, recursion_depth);
 
       context->using_buffer = FALSE;
 
@@ -251,10 +282,10 @@ do_plasma (PlasmaContext *context,
       if (x1 == x2 && y1 == y2)
         return FALSE;
 
-      gegl_sampler_get (context->sampler, x1, y1, NULL, tl, GEGL_ABYSS_NONE);
-      gegl_sampler_get (context->sampler, x1, y2, NULL, bl, GEGL_ABYSS_NONE);
-      gegl_sampler_get (context->sampler, x2, y1, NULL, tr, GEGL_ABYSS_NONE);
-      gegl_sampler_get (context->sampler, x2, y2, NULL, br, GEGL_ABYSS_NONE);
+      get_pixel (context, tl, x1, y1);
+      get_pixel (context, bl, x1, y2);
+      get_pixel (context, tr, x2, y1);
+      get_pixel (context, br, x2, y2);
 
       ran = context->o->turbulence / (2.0 * recursion_depth);
 
@@ -311,14 +342,14 @@ do_plasma (PlasmaContext *context,
   if (x1 < x2 || y1 < y2)
     {
       /* Top left. */
-      do_plasma (context, x1, y1, xm, ym, plasma_depth - 1, recursion_depth + 1, level);
+      do_plasma (context, x1, y1, xm, ym, plasma_depth - 1, recursion_depth + 1);
       /* Bottom left. */
-      do_plasma (context, x1, ym, xm, y2, plasma_depth - 1, recursion_depth + 1, level);
+      do_plasma (context, x1, ym, xm, y2, plasma_depth - 1, recursion_depth + 1);
       /* Top right. */
-      do_plasma (context, xm, y1, x2, ym, plasma_depth - 1, recursion_depth + 1, level);
+      do_plasma (context, xm, y1, x2, ym, plasma_depth - 1, recursion_depth + 1);
       /* Bottom right. */
       return do_plasma (context, xm, ym, x2, y2,
-                        plasma_depth - 1, recursion_depth + 1, level);
+                        plasma_depth - 1, recursion_depth + 1);
     }
 
   return TRUE;
@@ -343,8 +374,6 @@ process (GeglOperation       *operation,
   context = g_new (PlasmaContext, 1);
   context->o = GEGL_PROPERTIES (operation);
   context->output = output;
-  context->sampler = gegl_buffer_sampler_new_at_level (
-    context->output, babl_format ("R'G'B' float"), GEGL_SAMPLER_NEAREST, level);
   context->buffer = g_malloc (TILE_SIZE * TILE_SIZE * 3 * sizeof (gfloat));
   context->using_buffer = FALSE;
 
@@ -357,18 +386,17 @@ process (GeglOperation       *operation,
 
   context->gr = g_rand_new_with_seed (context->o->seed);
 
-  do_plasma (context, result->x, result->y, x-1, y-1, -1, 0, level);
+  do_plasma (context, result->x, result->y, x-1, y-1, -1, 0);
 
   /*
    * Now we recurse through the images, going deeper each time
    */
   depth = 1;
-  while (!do_plasma (context, result->x, result->y, x-1, y-1, depth, 0, level))
+  while (!do_plasma (context, result->x, result->y, x-1, y-1, depth, 0))
     depth++;
 
   g_rand_free (context->gr);
   g_free (context->buffer);
-  g_object_unref (context->sampler);
   g_free (context);
 
   return TRUE;
@@ -417,7 +445,7 @@ gegl_op_class_init (GeglOpClass *klass)
     "title",              _("Plasma"),
     "categories",         "render",
     "position-dependent", "true",
-    "reference-hash",     "06418af5f015f21fab965ecf439d95f7",
+    "reference-hash",     "f5b2ec90eaf0b44d9b06130b3abb73c9",
     "license",            "GPL3+",
     "description", _("Creates an image filled with a plasma effect."),
     NULL);