Ocean, extending the ocean modifier to support additional spectra

Archive Blender Development
18

I’m fighting with the ‘create diff’ tool. I have a local diff that I created, isolated to the change pinning the spectra to the surface (allowing for the resolution to be changed without the surface fundamentally changing). The ‘create diff’ tool whines that :

Unhandled Exception ("AphrontQueryException")
#1048: Column 'filename' cannot be null

for reasons that I don’t understand. Diff is

diff --git "a/e:\\ocean.c" "b/blender\\source\\blender\\blenkernel\\intern\\ocean.c"
index 9faa61f..5c96258 100644
--- "a/e:\\ocean.c"
+++ "b/blender\\source\\blender\\blenkernel\\intern\\ocean.c"
@@ -812,6 +812,38 @@ void BKE_ocean_simulate(struct Ocean *o, float t, float scale, float chop_amount
   BLI_task_pool_free(pool);
 }
 
+unsigned int generateUID(float xCoord, float zCoord)
+{
+  // a very simple hash function. should probably do a better one at some point
+  register float angle;
+  register float length;
+  register float coordSq;
+  register float id_out;
+  unsigned int returnVal = 1;
+
+  if (zCoord != 0.0f && xCoord != 0.0f) {
+    coordSq = zCoord * zCoord + xCoord * xCoord;
+    length = sqrt(coordSq);
+    angle = xCoord / length;
+    angle = acos(angle);
+    angle *= 57.295779513082320876798154814105f;  // RadsToDegs(angle);
+
+    if (angle > 180.0f)
+      angle = 360.0f - angle;
+
+    id_out = coordSq + (length * angle) + 0.5f;
+
+   if (angle == 0.0f)
+      returnVal = (unsigned int)coordSq;
+    else if (zCoord <= 0.0f)
+      returnVal = (unsigned int)floor(id_out);
+    else
+      returnVal = INT_MAX - (unsigned int)floor(id_out);
+  }
+  return returnVal;
+}
+
+
 static void set_height_normalize_factor(struct Ocean *oc)
 {
   float res = 1.0;
@@ -986,10 +1018,13 @@ void BKE_ocean_init(struct Ocean *o,
   }
 
   /*srand(seed);*/
-  rng = BLI_rng_new(seed);
-
   for (i = 0; i < o->_M; i++) {
     for (j = 0; j < o->_N; j++) {
+      // This ensures we get a value tied to the surface location, avoiding dramatic surface
+      // change with changing resolution.
+      int new_seed = seed + generateUID(o->_kx[i], o->_kz[j]);
+
+      rng = BLI_rng_new(new_seed);
       float r1 = gaussRand(rng);
       float r2 = gaussRand(rng);