message: Depth transform works with pinhole camera too
diff: #include <utility>
  #include <visionaray/math/array.h>
  -#include <visionaray/matrix_camera.h>
  #include <visionaray/packet_traits.h>
  #include <visionaray/pixel_format.h>
  #include <visionaray/render_target.h>
  @@ -305,9 +304,9 @@ inline array<R, Num> make_primary_rays(
  // Depth transform
  //
  -template <typename T>
  +template <typename T, typename Camera>
  VSNRAY_FUNC
  -inline T depth_transform(vector<3, T> const& isect_pos, matrix_camera const& cam)
  +inline T depth_transform(vector<3, T> const& isect_pos, Camera cam)
  {
  matrix<4, 4, T> view_matrix(cam.get_view_matrix());
  matrix<4, 4, T> proj_matrix(cam.get_proj_matrix());
  