COD Bunker Roof Tutorial

This tutorial has been written in an attempt to explain how the bunker roof in COD mp_rocket was created. It is inspired by a tutorial written by maskedavenger. There were a few questions about how you might be able to lower the face (polygon) count and still end up with something that looks the same as both the mp_rocket bunker roof and maskedavenger's tutorial. This should serve as a good exercise in working with patches and terrain meshes.

First thing I did was to load up the multiplayer game and turn off pure server. Then I typed in \devmap mp_rocket to load the level and \r_showtris 1 to take a look at the geometry. It is somewhat difficult to see exactly what is going on because of the surrounding geometry but I think I got the general idea behind what was done.

Time to start up CoD Radiant and just leave the grid on the default setting for now (Grid8). We do most of this in the top view so that's where we'll start.

In the top viewport. drag out a brush that's 128x384 in size. Then go to Patch/Simple Patch Mesh and select the default of 3x3.



Now we are going to go into bend mode (hit "B" on the keyboard). For our first selection hit tab to select the vertices shown below then hit enter on the keyboard.



For the next selection just hit enter on the keyboard again. For the final selection before we bend the patch select the vertices on the left side of the patch. They should be selected by default so all you really have to do is hit enter. Switch to the front view and drag up with the mouse until you have this:

This gives us the base patch we will use to do the sides and corners for the roof. In the image above you can see that the patch is now one grid space above the major grid lines. To make it nicer to work with drag it down one grid space in the front view so that the patch is inside the major grid lines. Not that it makes any difference because it doesn't.

Return to the Top view and clone the first patch using the spacebar. Move it above the first patch and then resize it to 64x128.

We are going to bend this into our corner patch. We only have to do this once, then we will clone our first two patches to make the other sides of the roof.

Hit "b" to get into bend mode. For the first selection, shown below, just hit enter.

For our next selection we want to hit tab and select the vertex shown below:

Our final selection should be the vertices at the top of the patch, then hit enter.

Drag down with the mouse until you get a 90 degree bend. You should end up with something that looks similar to this, although it may not be exactly the same:

I have a corner with 4 segments and I really want to have 8. Sometimes this bend operation will give you 4, sometimes 8 sometimes 6. In any case to fix this up so that it looks like what we want you will have to use the keyboard shortcuts "shift + ] " and "shift + [ ". Use these to decrease or increase the number of segments in your patch until you have 8 and it looks like the image below:

Now we can select the first two patches, clone them using the spacebar and then rotate them (rotate along the z axis) to create additional sides for the bunker roof.



If you take a close look at the corners you can see that at a grid setting of Grid1 they are all perfectly matched to the gird, which will be important for this next step.

The Tricky Part

After looking at the original mp_rocket roof I noticed there was some funny stuff going on when the original designer trimmed the top corners. I could see a crisscross pattern in the top corners of the roof so the next section of this tutorial will attempt to illustrate how I think they did it. Since this roof design has already been relatively expensive as far as face count goes there are a few tricks involved in keeping our poly count low. Remember, I am simply trying to reproduce the steps taken by the original designer here, there are always alternative ways of doing the same thing.

Zoom into the top right corner in the top view. I am going to start by drawing a brush that is 64x64 in size and then converting that brush into a simple terrain mesh.



Terrain in CoD is fantastic and the developers have done a tremendous job of making it easy to work with by allowing designers to manipulate a terrain mesh at the vertex level. For our terrain settings I am going to select a width of 2 and a height of 5. You will end up with something that looks like the image below:

Move this terrain so that the top right corner touches the inside center of the corner patch, like the image below:

We are now going to switch into vertex mode (keyboard "v") and start moving the vertices so that they match up with the vertices in our corner patch. You can start this operation at a grid size of Grid4 and then once you have the vertices close switch to Grid1 and place them exactly. In the image below I have added some rough (very rough) arrows to show you where you place each vertex.



You will end up with something that looks like the image below:

Now just clone and rotate (along the z axis) this corner trim to fill the remaining 3 corners. You could probably get the same effect by using the cap from a bevel, which we will discuss shortly.

The rest of the top of the bunker roof can be filled in with a few patches. I placed one large terrain patch in the center to cover from top to bottom and then added two smaller patches to fill in the gaps at the sides. In both cases I set the terrain options to width 2 and height 2. The center patch is 384x512 and the sides are 64x384. After you have done this check it in the front or side view to make sure everything is level and in place.

The completed roof top.


Now that we have completed the top section we can move on to covering up the bottom. I mentioned bevel caps earlier and we are going to use bevel caps to finish off this roof.

In the top view draw a brush that is 128x128 over the top right corner. You could actually do this anywhere but I am using the corner patch as reference. We are going to turn this into a bevel but before we do go to the front or side view and drag it to a depth of 64. This is not really too important but it makes selecting and deleting the parts of our capped bevel a little easier.

Go back to the top view and select Patch then Bevel from the menu bar. Rotate on the z axis until it is flowing in the same direction as the corner patch. You can see that at this point the bevel does not match our corner but we will fix it up later.

Now I am going to cap the bevel. Select Patch from the menu bar and then Cap/Normal. The first option which is "Bevel" should be selected. Click OK. Select Patch/Matrix/Invert. We can now delete the top section and the middle of the bevel since we only want to keep the bottom cap. In the image below I have moved the bevel and caps over to the side a little so that you can see what to keep and what to delete.

The next part is a little more difficult. Switch into vertex mode (v) and move the top right vertex towards the center to the patch cap. You will have to switch down to Grid1 and try to get the cap to match up with the corner patch. Stop moving the vertex once you have matched the image below.



You can see that it does not line up yet so hit "shift + ] " to force it to a higher density. Now it will line up with the outside of the corner patch. Clone and rotate this into the remaining 3 corners.

To complete the roof we just need to add a few more patches to fill in the gaps. I created 4 patches to go around the outside bottom part of the roof.

Since we want the inside center of the roof to be slightly raised I suggest going into the front view and creating a patch 384x16 or 384x8 and then cloning and rotating it to create the top sides of the inner ceiling. Basically you use patches to draw a box with no bottom that you can position in the center of your ceiling.

Texturing this will require a certain degree of patience.

Hope this is useful to those that are interested.