BLI: Add "is_zero" method to float2 and float3 types

This is not necessary, but a nice convenience to avoid using `is_zero_v3`.

Differential Revision: https://developer.blender.org/D10713

source/blender/blenlib/BLI_float2.hh

@@ -65,6 +65,11 @@ struct float2 {
     return len_squared_v2(*this);
   }
 
+  bool is_zero() const
+  {
+    return this->x == 0.0f && this->y == 0.0f;
+  }
+
   float2 &operator+=(const float2 &other)
   {
     x += other.x;

source/blender/blenlib/BLI_float3.hh

@@ -174,6 +174,11 @@ struct float3 {
     return len_squared_v3(*this);
   }
 
+  bool is_zero() const
+  {
+    return this->x == 0.0f && this->y == 0.0f && this->z == 0.0f;
+  }
+
   void reflect(const float3 &normal)
   {
     *this = this->reflected(normal);