Modeling Knight

39 knight

Last but not least, it is time to model the knight. I hope till now you are a little confident while working with dimensions because this section is going to have plenty of measurements.

Begin by creating a new database named knight.g.

The Knight piece can be broken down into four sections: base, body, neck and the top. Starting with the base which is same as the other pieces, type in the MGED command window:

in base.rcc rcc 0 0 0 0 0 1.1 2.25 ENTER

Now, coming to the body. The body section is made up of two shapes; arb6 and rpp. You are already familiar with rpp (Rectangular Parallelepiped), so let’s get you introduced with arb6 (Arbitrary Convex Polyhedron, 6pts) You will use a shape like the one given below:

40 arb6 rpp

While making this shape using the in command, MGED will ask you to enter the values of all six points. The following image gives an idea of the points:

41 arb6

You will use this shape to make the left part of the body section. To insert this shape, type:

in body1.arb6 arb6 ENTER

MGED will then ask you to enter x, y, z values of all six points, one by one. Let’s understand each point and its value.

For point 1, type

0.65 0.5 1.1 ENTER

For point 2, type

0.65 0.5 2.9 ENTER

For point 3, type

0.65 -0.5 2.9 ENTER

For point 4, type

0.65 -0.5 1.1 ENTER

For point 5, type

1.75 0.5 1.1 ENTER

For point 6, type

1.75 -0.5 1.1 ENTER


  • 1.75 = radius of base.rcc (2.25) - the distance of the body from the edge of base (0.5)

  • 0.5 = half of body’s width

  • 1.1 = height of base.rcc

  • 2.9 = height of base.rcc (1.1) + height of body (1.8)

To make the other part of the body, type:

in body2.rpp rpp -1.75 0.65 -0.5 0.5 1.1 2.9 ENTER

This is what we get as output:

42 knight body

Moving on to the neck, it also consists of two parts. You will make two rpp. As you look at the target design, the left side of the neck has a slightly greater height than the right side. So, to make two rpp of different heights, type:

in neck1.rpp rpp 0 1.75 -0.5 0.5 2.9 3.7 ENTER

in neck2.rpp rpp -1.75 0 -0.5 0.5 2.9 3.4 ENTER

The top also has two parts, left and right arb6. The left one starts from the top of neck1.rpp and the right one starts at the top of neck2.rpp. Also, the right arb6 has a height slightly greater than the left one. To get the shapes, type:

in top1.arb6 arb6 ENTER
0 0.5 3.7 ENTER
0 0.5 5.2 ENTER
0 -0.5 5.2 ENTER
0 -0.5 3.7 ENTER
1.75 0.5 3.7 ENTER
1.75 -0.5 3.7 ENTER
in top2.arb6 arb6 ENTER
-1.75 0.5 3.4 ENTER
0 0.5 5.4 ENTER
0 -0.5 5.4 ENTER
-1.75 -0.5 3.4 ENTER
0 0.5 3.4 ENTER
0 -0.5 3.4 ENTER

On a side note, these commands can be written in the shorthand method with all the values in a single row separated by spaces.

Our Graphics Window looks like this:

43 knight azel view

And in Left view:

44 knight left view

Type the following command to make the region:

r knight.r u base.rcc u body1.arb6 u body2.rpp u neck1.rpp u neck2.rpp u top1.arb6 u top2.arb6 ENTER

Now, assign the material properties to this knight and redraw your design. Type:

mater knight.r plastic 0 0 0 0 ENTER

B knight.r ENTER

After raytracing your design looks like:

45 knight rt azel view

In Left view:

46 knight rt left view

There is a color difference because the part above is plain and the bottom area is round.