Lots of progress on octrees

luprex/core/cpp/util.hpp

@@ -262,6 +262,16 @@ eng::string hash_to_hex(const HashValue &hash);
 // This is a good hash, but not cryptographically good.
 uint64_t hash_ints(uint64_t n1, uint64_t n2, uint64_t n3, uint64_t n4);
 
+// Hash a single 64-bit integer.
+// This is a good hash, but not cryptographically good.
+// Published by David Stafford in his article 'Better Bit Mixing'.
+inline uint64_t hash_int(uint64_t x) {
+    x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
+    x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
+    x = x ^ (x >> 31);
+    return x;
+}
+
 // Convert a 64-bit hash value into a floating point number between 0 and 1.
 double hash_to_double(uint64_t hash);
 
@@ -319,6 +329,9 @@ struct XYZ {
     XYZ(float ix, float iy, float iz) { x=ix; y=iy; z=iz; }
     bool operator ==(const XYZ &o) const { return x==o.x && y == o.y && z==o.z; }
     bool operator !=(const XYZ &o) const { return x!=o.x || y != o.y || z!=o.z; }
+    XYZ operator -(const XYZ &o) const { return XYZ(x-o.x, y-o.y, z-o.z); }
+    XYZ operator +(const XYZ &o) const { return XYZ(x+o.x, y+o.y, z+o.z); }
+    XYZ operator *(float scale) const { return XYZ(x*scale, y*scale, z*scale); }
     eng::string debug_string() const;
 };