# Modeling 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:

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:

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

Here,

• `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:

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:

And in 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:

In Left view:

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