Fixed double define bug

src/utility.cpp

@@ -64,6 +64,6 @@ std::array<float, 3> operator/=(std::array<float, 3>& v, const float d){
 
 glm::mat4 scale_z(float z0, float factor){
   glm::mat4 transf (1.f);
-  glm::mat4 transf = glm::translate(glm::scale(glm::translate(transf, glm::vec3(0.f,0.f,-z0)), glm::vec3(1.,1.,factor)), glm::vec3(0.,0.,z0));
+  transf = glm::translate(glm::scale(glm::translate(transf, glm::vec3(0.f,0.f,-z0)), glm::vec3(1.,1.,factor)), glm::vec3(0.,0.,z0));
   return transf;
 }