hi there,

i want to rotate/transform a vector, but i dont get it quite right. i’m using glm.

here’s my c++ code:

```
glm::vec3 Collision::Polytope::FurthestPoint(
const glm::mat4& transform,
const glm::vec3& direction) const
{
if (Points.empty())
{
cout << "error Collision::Polytope::FurthestPoint(): polytope has no points" << endl;
return { 0, 0, 0 };
}
vec3 p0 = transform * vec4(Points.at(0), 1);
float max_distance = dot(p0, direction);
vec3 furthest_point = p0;
for (auto& point : Points)
{
vec3 p = transform * vec4(point, 1);
float distance = dot(p, direction);
if (distance < max_distance)
continue;
max_distance = distance;
furthest_point = p;
}
return furthest_point;
}
```

what i’m doing here is:

i transform all points of a (convex) polytome (or mesh) using a “mesh-space to world-space” transformation (just translation + rotation, NO scaling). then i’m figuring out whith point lies furthest in a certain direction (in world-space).

what i want to do is to transform the direction, not each vertex (because it might be faster that way).

replacing “vec3 direction” with “inverse(transform) * vec4(direction, 0)” doesnt work.

what am i missing ?? thanks in advance!