C++ (Cpp) Vec2f::negate示例

// Translate branch on 0.1 of vector [v1,v2]
void RefinementState::stretchBranch (const Filter &branch, const RefinementState &state, int v1_idx, int v2_idx, int val)
{
   int i;
   float r, sh = 0.1f * val;

   const Vec2f &v1 = state.layout[v1_idx];
   const Vec2f &v2 = state.layout[v2_idx];
   Vec2f d;

   d.diff(v2, v1);
   r = d.length();

   if (r < EPSILON) 
      throw Error("too small edge");

   d.scale(sh / r);

   if (branch.valid(v1_idx))
      d.negate();

   layout.clear_resize(state.layout.size());

   for (i = _graph.vertexBegin(); i < _graph.vertexEnd(); i = _graph.vertexNext(i))
   {
      if (!branch.valid(i)) 
         layout[i].sum(state.layout[i], d);
      else
         layout[i] = state.layout[i];
   }
}