This mod renders all havok collision objects as wireframes on top of the scene. It draws all rigidbodies and phantoms that are added to the current havok world. It also draws constraint pivot points for ragdoll and hinge constraints.
It's useful for things such as visualizing the collision of your hands/weapons, NPCs, trigger volumes, or debugging collision issues.

To enable/disable the collision viewer, type trd in the console. This is an unused console command from the base game.

This mod should have no impact on your game while the viewer is not active, and can be kept installed without issues even if you aren't actively using it.

When you first enable the viewer, or move within range of a new object that hasn't been encountered yet while the viewer is active, you will notice a brief freeze as the geometry for the new collision object is created. After this, it is cached until the viewer is toggled again.

There are several configuration options that can be changed in the accompanying ini file. This includes things such as the distance at which to draw objects, what kinds of objects to draw, which collision layers to draw, and what color to draw different collision layers.
Note that character controllers are not drawn by default, in favor of drawing the actual character ragdolls (when using PLANCK). To draw character controllers as well, remove the layer from the `ignoreLayers` ini setting.
To draw the player's character controller, set the `drawPlayerCharacterController` ini setting to 1.
The majority of options are reloaded whenever you toggle the collision viewer console command.

You may notice that for some objects, the collision you see in-game does not match what you see in the mesh file (in nifskope / etc.). This is due to an optional collision setting called the convex radius of the object, which nifskope does not take into account when showing collision.

The convex radius is an additional distance from the defined collision mesh where collision will still occur. It basically extends the collision mesh by that radius.



It's not easy to render the shape with the radius incorporated, since it produces smooth corners between triangles.
This mod tries to approximate the mesh extension by duplicating and moving the mesh's vertices outwards in the direction of the triangle/vertex normals.
Black is the original collision mesh, as seen in nifskope. Red is what is drawn by this mod. Green is the true collision, and what you'll actually experience in-game.



This approximation should be good enough for most objects. It's accurate except for at the corners where triangles meet, where the true collision (green) extends further than what this visualizer shows (red). This discrepancy is usually minor, but for large triangles that meet at large angles, it is noticeable (objects will touch in reality before they appear to touch in the visualizer).

Thanks to Nukem for reverse-engineering a ton of the Skyrim SE renderer.