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| Figure 1.3: Disc Parameters. |
To avoid the need to move our work to a new layer when we have finished this section move to layer three, so that our Robots head will be created there. Now on to the actual modelling.
Perhaps strangely while the Box, and Ball primitives are named after their three dimensional form (setting one axis to zero size, will make a Square, or disc) the primitive we use to create a cylinder is called Disc. The Disc tool which we will use to make the basic shape of the robots head is located under the Create tab.
Select the Disc tool and enter the values shown in Figure 1.3 this should
create a flattened cylinder above the z-axis. Now drop the Disc tool.
Now if you looked carefully at the picture of the finished robot you would probably have guessed that the head is also a SubPatched form. If you think back to the previous section you should also recall that only Tris and Quads can be converted to SubPatches. Now look carefully at the ends of the cylinder we created, they have Eight points each. So what can we do? Well we are going to convert them to a number of Quads.
First select the two ends of the cylinder, this time we'll use the Polygon Statistics panel. Check that you are in Polygon selection mode (ie the button labeled Polygons is highlighted at the bottom of the window). Now press 'w' To bring up the statistics window, as we are in Polygon selection mode this will show the statistics for polygons. Check that the number next to 'Total' is zero, if it isn't then click the '-' in the column to the left to deselect all polys.
Further down the Polygon Statistics window is the '>4 Verticies' row, click the '+' symbol to select all the polygons with more than four points (in our case the two ends of the cylinder). Close the Polygon Statistics window.
Now select the Knife tool either from the Construct tab, or by using the Keycut 'K' (note shift must be held). The Knife tool defines a plane along which all selected polygons are divided, the plane is defined by two points and selection of one of the three axis (along which the plane remains constant).
As with most of Lightwaves tools the Knife tool can be controlled using the mouse, or the numeric requester. For this job we'll use the mouse, but it is vitally important that you perform this step acurately.
Go to either the Front or Back view, now make sure that the object fills the viewport. With the Knife tool selected Press the left mouse button and drag a line from one side of disc to the other. The line should pass through the two points that are furthest apart on the X-Axis (ie it should bisect the disc horizontally). Hit the 'Spacebar' to confirm the change and deselect the tool.
Now use the same technique to divide the disc in to two halves vertically.
At the end of this operation you should see your disc divided perfectly into quarters.
The ends of the cylinder will now both be made of four quads, which can be converted
to SubPatches.
For those who are curious why not deselect everything, and convert the head to SubPatches ('TAB') just to see what it looks like so far.
Right now it's time for the cut, if necessary convert the head back into polygons ('TAB'). Now make sure you have a viewport from either the Top or Bottom view and that the head fills that viewport. Select the Knife tool ('K'), and make a cut from the left of the head to the right of it so that it cuts a very thin section of the top of the cylinder in your viewport.
Drop the Knife tool, and convert the object into SubPatches.
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| Figure 1.4: Stretch Parameters. |
In the Top or Bottom viewport select the bottom row of points (these are the nine points which make up the back end of the cylinder). We will now scale these points to give head a more interesting shape.
Lightwave offers two tools for this sort of operation Size and Stretch. For this task we'll use the more flexible 'Stretch' tool which can be found under the Modify tab, or can be activated by pressing 'h'. For this operation we'll use the Numeric requester again 'n'.
Invoke the Stretch tool and then call up the Numeric requester and enter
the values shown in Figure 1.4, this will scale down back end of the head
cylinder. It is important that the scaling is performed relative to the centre of
the disc we are scaling so that it is not moved out of place by the operation.