BetterSpace: Whitestar Tutorial

Lesson 9a:
Building The Lower Hull (gulp)

Take a deep breath. We will now attempt to build the spline cage for the lower hull of the Whitestar. This will be the most challenging section yet. When I built my first Whitestar model all those years ago, this was the section I built first, because I knew that if I could build this, the rest would be easy. For yourself, consider this to be the culmination of all the skills you have learned and practised while following this tutorial.

At the bottom of this page is a set of images showing the completed section in half-wireframe / half shaded view, so that you can try to visualise our goal.

Building this section involves creating 40 curves, consisting of 179 points. The finished cage looks like a complete disaster, with curves snaking around each other and generally being very unpleasant to work with. So prepare yourself with ample amounts of your favourite stimulant, and let's dive in.

1)	Previous Step \| Next Step

the completed section

Here you see the completed section that we must now build. I have overlayed the spline cage so that you can see roughly how the cage correlates to the mesh. If you roll your mouse pointer over the image, assuming you have Javascript enabled in your browser, the image will change to show only the spline cage. I hope this gives you an idea of the overall structure of the object.

Let's get building.

Firstly, you will need to create the main rail curve for the object. Don't worry too much about scale right now, as you can easily correct the scale of the object later to match the rest of your sections. For your information, the grid size in the image below is five meters.

the main rail curve. grid size is 5m

This curve is created with all points x=0.

This is a close-up of the left-end of the above curve. Notice the control point.

detail of left-end of curve. Grid is 500mm

2)	Previous Step \| Next Step

Next, we must create a second rail curve. As you can see from the image, this curve follows the first curve fairly closely, except that it is further out in the x-direction. It also tapers in towards x=0 as it nears the right side of the image.

second rail curve, top and side view

As before, the cluster of points on the left end of the curve have a control point, in exactly the same way as the first rail curve.

3)	Previous Step \| Next Step

A third rail curve now. Again, this curve roughly follows the path of the first and second curve, but this time it is slightly shorter, and tapers out, away from the x-axis towards the right of the image.

third rail curve, top and side view

There is a control point at the right end of this curve, as shown in the image below.

third rail curve, top and side view

These three curves form the basis of the long central piece of the lower hull.

The next image shows the three curves together in the perspective viewport. I have named the three curves r1, r2 and r3, with r1 being the first curve we created.

perspective view of rail curves

4)	Previous Step \| Next Step

One further rail now.

rail curve number four, r4.

If you look closely at the third point from the left you will notice that there appears to be two points very close together. This is exactly what is going on. The reason why there are to points is to force a fairly sharp change of direction in the curve. The following image shows this in more detail. Also notice the control point at the left of the image.