Introduction

We are now going to start to model the racetrack. In this part, we are going to learn how to use curves to form our basic track shape which is the most efficient way to begin this type of model.

Adding curves

To start off, we need to add a bezier curve. Bring up the main menu by pressing ‘SPACE’ and select ‘Add > Curve > Bezier Curve’. You will notice a curved line appear in the 3D view. Now, move it to a part on the outside of the track so you can begin to ‘trace’ around it.

To move and adjust the curve simply move the different vertices around (The small dot handles) by right clicking on them and pressing the G key or drawing a movement line. The vertex in the center of the three at each point moves the curve and the two on the outside rotates it

You can also perform all the other basic transformations like size (’S’ key) and rotation (’R’ key). To accurately select the vertices, press the ‘B’ key once for box select and the ‘B’ key twice for circle selection which I find is the best way because you have more control over what you are selecting (use your scroll wheel or +/- to increase/decrease the size of the circle and press ‘ESC’ to exit it).

Tracing the track

Now that you are familiar on how to transform the curve, just start to try and follow the outside of the track with it. You can add another joint by either selecting the center vertex on one of the sides, holding ‘SHIFT’ and again right clicking on the center vertex or by pressing ‘E’ to extrude it. You can disable the transformation widget if it gets in the way by deselecting the hand button in the 3D window toolbar. It should look start to look something like this:

If you’re panicking because you haven’t got the hang of transforming the curves, don’t worry, keep experimenting and you will get there eventually. It took me a while to get used to it as well, so you’re not alone!

When you’re happy, carry on adding curves all the way around the track. Once finished you’ll probably be thinking "is there a way to join them up?" well yes there is, if you press ‘C’ it will join the two ends of the curves together. However, I suggest that you don’t do this because it will prove to be a problem when it comes to editing the mesh. You can easily join it up manually after converting the curves. By now it should look something like this:

Adding depth

Now that we have traced the outline of the track, we can start to add depth. So, exit edit mode (’TAB’) and add another bezier curve (’SPACE’ > Add > Curve > Bezier Curve). This curve profile is what we are going to use to extrude around the track to form the road. So that we don’t end up with a wonky mesh, we need to straighten the curve. You can do this by pressing ‘V’. Depending on what you want your track to be like, you can add more curve joints. This will add another mesh column to your track so you can add things like a track side, barriers and rumble strips. For my track, I am going to add just two extra joints for the inner landmass and the outer landmass. You’ll need to think about this carefully, because if you decide to add barriers and rumble strips later on, it won’t be an easy task. My curve now looks like this:

Next, to extrude the curve around the track we need to associate it with a name. Exit edit mode (’TAB’) and go into the ‘editing’ buttons. In The OB field in the far left box, enter a name (I usually call mine ‘cur’). Then, select the track curve and again in the editing buttons panel, in the far right box, enter the name you just called your extrusion curve into the BevOB field. If you now enter wireframe mode (’Z') you will notice that it looks something like this:

Looks a bit of a mess, doesn’t it? To sort out the overlapping all we need to do is increase the size of the track curve. Enter edit mode (’TAB’) and press ‘A’ to select all the vertices , then increase the size with ‘S’. You can also fiddle about with the ‘Width’ property in the ‘Curve and Surface’ box which acts in a similar manner. When you then exit edit mode from the first method you will notice that the track looks a lot cleaner, as shown here:

Unfortunately, the track is now way too thin. Just have a play about with the track profile curve until you have it at an appropriate width. Don’t worry if it slightly overlaps at places, we can sort that out when we convert it to a mesh.

We now need to start to take into account that this track is going to be integrated into a game (well not as such, but we are assuming so) and the amount of polygons (faces) in the track looks slightly high and we need to reduce them. This will not only help the game performance but it will also make it much easier to close up the mesh later on. Because the track is still in curve mode we can control and adjust it however we want.

In the ‘Curves and Surfaces’ box there is a grey field that says ‘DefResolU:’. At the moment, it is set to 12. Have a go at increasing and decreasing this value. You will see it automatically adjust the amount of overall polygons. A lower value will be easier to work with through this tutorial, and better for low polygon tracks. If, however, you feel that the track is too jagged at the edges, or you want a smoother track, by all means increase the value. I chose a low value of 8 for the purpose of this tutorial. If you are feeling confident, keep it at 12.

At this point I would begin cleaning up the design. Remember that when in-game you don’t want corners to be too sharp or the road to be a bit wonky, especially if you are aiming for a professional-style track.Enter edit mode and tweak the curves until everything is just about perfect (I would turn off the background while doing this). At this point it should look something like this:

Adding elevation

Finally, now that the track design is done you can enter perspective mode and start to add some elevation. Before you can transform the curves in 3D space, you need to enable it. Just below the ‘DefResolU:’ field are three buttons, one of them labeled ‘3D’, select it and then you can begin.

You can switch to perspective mode by pressing ‘Num 5′. To add elevation, just enter edit mode, select the curve joint you want to change, press the ‘G’ key and then press ‘Z’ to move it vertically. You may not be able to make it out too well at this point, but here is what my track looks like with some elevation:

Conclusion

We have now finished with curves, in the next part we will move onto converting the track to a mesh and adding the landmass and start to get it to look like a real race track.