# The Dromesday Book

### Site Tools

dromed:three_cylinders

# Smooth Curves using the 3 Cylinders Trick

:T1: :T2: :SS2:

## Introduction

Cylinders can have a maximum of just 10 sides, which isn’t enough for large curves. There’s a technique involving 3 cylinders that allows you to effectively double that limit.

This tutorial explains how to make a smooth archway that is 8 feet wide, and a pillar whose size is up to you.

### NewDark Update

The New Dark patch has increased the maximum number of sides to 26. In most cases this eliminates the need for this tutorial, however the techniques below can be used if the new limit is still not enough.

## Arches

#### Cuboid

Create a fill air cuboid that is 8 feet wide and 6 feet high.

#### 1st Cylinder

• From the Shapes menu, set the number of sides to 10, then select Align by Sides.
• Align by sides is important step if you want the curve to line up with some other terrain, e.g. a cuboid forming the bottom of an archway.
• Create the cylinder. Set the Depth and With to 8.
• Because it’s aligned by sides, the distance between the sides will be exactly 8, whereas the distance between the vertices will be a little more than 8:
• If the archway is to be elliptical, only the Depth needs to be 8.
• Rotate the cylinder so that the vertices are in line with the top of the cuboid, and set the Op to solid→water\

#### 2nd Cylinder

• Clone the 1st cylinder and set the Op to evaporate. Then swap the Heading, Pitch and Bank values to that 0 becomes 90, and 90 becomes 0\
• If the archway is meant to be elliptical, also swap the Depth and Width values.

#### 3rd Cylinder

• Clone the 1st cylinder, and set the Op to water→solid\
• The 3rd brush does not have to be a cylinder. It can be any shape that completely surrounds the 1st cylinder.

#### Cuboid

Create an 8 by 6 cuboid as in the previous example.

#### 1st Cylinder

• Set the number of Sides in Base to 8, and Align by Sides.
• Create the cylinder, with a Width and Height of 8.
• This technique cannot make ellipses, only circles. See the above section for ellipses.
• Set the Bank to 90. This gives a cylinder that runs east/west. Don’t swap the Pitch and Bank to make it run north/south; set the Heading to 90 instead:
• Set the Pitch to 22.5 so that the corners are lined up with the top of the cuboid, and set the Op to solid→water\

#### 2nd Cylinder

• Clone the 1st Cylinder, and set the Bank to 0, and the Op to evaporate\

#### 3rd Cylinder

• Clone the 1st cylinder, and set the Op to water→solid\

## Pillars

For a narrow pillar, 10 sides may be enough, so the following is more suitable for larger pillars or rounded buildings. Or if you just want your mission to look gorgeous.

#### 1st Cylinder

• Set the number of sides; 6, 8 or 10 depending on how big the structure is to be.
• Select Align by Sides if you want the pillar to line up with other brushes (e.g. a semicircular tower attached to the end of a cuboid).
• Set the Op to Fill Water or Flood. The latter can be more suitable if fill water would cause problems with the surrounding terrain.
• Create the cylinder, setting the appropriate Depth and Width.
• Once again, 8 sided cylinders can’t be used for elliptical curves, but 6 and 10 can be.

#### 2nd Cylinder

• Clone the 1st cylinder, and change the Heading. Suitable values depend on the number of sides:
• 6 or 10 sides: Heading: 90
• If the curve is elliptical, swap the Depth and Width of this cylinder.
• Set the Op to water→solid.

#### 3rd Cylinder

• Clone the 1st cylinder, and set the Op to evaporate.

## Archway with Solid Frame

Nothing stopping you using both of the above techniques together. You need to use the same rotations as in the ‘Arches’ method.

#### Solid Frame

• Create a solid cuboid.
• 1st cylinder: flood (not fill water).
• 2nd cylinder: water→solid.
• 3rd cylinder: evaporate.

#### Arch

• The same is the ‘Arches’ method.

## Textures

The presence of 3 overlapping brushes will cause texturing issues, especially when you change the assigned textures.

• The texture on the 1st cylinder doesn’t matter. It gets overridden by the 3rd cylinder.
• Where the ends of the cylinder are flush with the terrain (i.e. a wall or the floor/ceiling), the cylinder’s face texture will be shown.
• In this screenshot, the 2nd and 3rd cylinders have different textures to the surfaces on both the inside and outside the arch:
• The texture problem only becomes obvious after portalizing, so it’s an easy thing to miss.
• In short, the top/bottom of the cylinders must have the same texture as any surface they are flush with.