Building & Scripting Objects in Second Life

This week we shall have a look at how to build (very basic) objects in Second Life and how we can use scripts to add interactivity to these objects.

So let’s get straight down to business…

Building Basics

Second Life provides tools that enable you to create whatever your imagination conjures up. The only limits are practice and your own imagination! The building blocks for most everything in second life are known as Primitives or ‘Prims’ for short. Prims are basic shapes, such as cubes and spheres, provided by the building tools that can be combined together to create the larger more complex shapes in your creation. In total, there are around 15 prims of different shapes at your disposal.

To start building, you must be in an area in which you are allowed to build. This could be your own land, someone else’s land (if the owner gives you permission) or a sandbox, a public area where people can build stuff to their heart’s content. One thing to note about sandboxes is that the objects built in them are only temporary since sandboxes are periodically cleaned by their owners. To avoid losing your creation, make sure to save it in your inventory!

Editing Objects

So, we know where to build and with what to build but how do we actually build stuff? To start building, right-click anywhere on the ground and select “Build” from the context menu. This brings up the build toolbox shown below:

With the magic wand tool selected, choose the desired prim shape and click anywhere on the ground to create the object, a process known as “rezzing” a prim.  Now that we have created our basic object we can go ahead and change pretty much anything about it. An object can be moved, rotated, resized, hollowed out, twisted, tapered… the list goes on. You can also change the texture of the object (the default texture is wood).

To move an object, select “Move” from the toolbox and use the arrows provided to move the object in the desired direction. Similarly selecting “Rotate” and “Stretch” from the toolbox will allow you to rotate and resize an object in 3 dimensions. The X, Y and Z axis’ in Second Life are colour-coded Red, Green and Blue respectively and the control surfaces provided to manipulate the object follow this standard as illustrated below:

Moving an object

Rotating an object

Resizing an object

You can also manually set numerical values for moving/rotating/re-sizing objects rather than using the control surfaces for more precise control.

Building a Chair

A chair is a good candidate to demonstrate how to use the build tools to create something that is actually useful. My chair will have four wooden legs and fabric-covered seat and back, nothing too fancy. Here’s the finished product:

The finished product

The first step is to create all the basic components of the chair independently of one-another starting with the seat. The seat is made from a cube prim which I flattened into the correct shape. I then took a copy of the seat and rotated it around the x-axis to make the back. I also re-sized the back to make it slightly narrower than the width of the seat. Finally I used another cube prim to create the first of the legs which I copied 3 times to create the set. At this point I should mention some pretty handy shortcuts I found for copying and rotating objects which make the process much quicker than having to go back to the build toolbox each time. To copy an object make sure it is selected, then hold down the ‘shift’ key and click and drag away from the object. This will create an exact copy of the selected object. To rotate an object, simply hold the ‘Ctrl’ key and use the rotation control surfaces to rotate along the desired axis. Here’s what the chair looks like before assembly:

The chair components

Before assembling the chair however I wanted to assign different textures to the various components. I wanted my chair to have a fabric seat and wooden legs. To change the texture of the currently selected part(s), goto the “Textures” tab in the build toolbox and click on the wooden texture thumbnail. This will open up the “Pick Texture” dialog box from where you can browse through all the available textures. I chose to go with the standard “Fabric Linen” texture found under the “Fabrics” folder.

Applying a texture

Similarly, a wooden texture is applied to the chair's legs.

The final step is assembling the chair, starting from the legs. To make it easier to see what I was doing, I opted to position the legs while the seat was still on the floor. I also made use of the “Snap To Grid” option to help me better position the legs relative to the seat. Snapping to the grid also made it much easier to equally space the legs.

Snapping to grid makes it easier to align objects

When I was happy with the position of the legs, I simply slid the seat along the Z-axis to bring it above them and correctly positioned (and slightly tapered) the back. Finally I selected all the parts and linked them together to make them behave like one object. Job done.

Introduction to Scripting

All scripts in Second Life are written in Linden Scripting Language, LSL for short, which is syntactically similar to C and Java. LSL scripts are interpreted and executed on the Second Life servers which send the results back to the viewer. LSL is state and event driven, meaning that an object can be in one of many states and transitions from one state to another by reacting to events. For instance a door can be open or closed (states) and can transition from one state to the other after being touched (event).

In my next post we will have a closer look at LSL and how we can add scripts to our objects. We shall also see how we can add interactivity to our objects by making them respond to commands.