This section of the tutorial is going to cover the basic types of geometry node. These are Box, Cylinder, Sphere, Cone and Text. There are more types, but they are more advanced and will be explained later on in another section. So, without further ado, let's get on with it! This one shouldn't take long...
The Box is exactly what is says, a cube or cuboid shape. The default Box is a cube, two metres to a side, centred on the origin. To make a Box of a different size, you can define it with an explicit size:
geometry Box {
size 5.5 3.75 1.0
}
This creates a Box with X, Y and Z dimensions as specified in the size parameter.
Textures are mapped onto the Box by applying them individually to each face. The texture is applied the obvious way up to the sides, and applied to the top so that if it is tilted towards the camera, the texture is the right way up. The bottom is texture-mapped the opposite way, so if the bottom is tilted towards the camera, the texture is the right way up still.
The Cylinder node is slightly more complex. The default is a cylinder from +1 to -1 in all dimensions, the same as the Box above (radius of 1, height of 2). This too is centred on the origin. To specify a different size, we can use the radius and height fields. There are also three other fields, side, top, and bottom. These are Boolean values (TRUE or FALSE), and tell the browser whether to display the appropriate section of the cylinder. These default to TRUE, so you don't need to put them in at all most of the time. However, if you had a cylinder where an end was obscured by another object, it would be worth turning off that end, as it will reduce the amount of work for the browser, speeding up the execution of your world.
geometry Cylinder {
radius 0.5
height 10
top FALSE
}
This gives a tall, thin cylinder with no top.
Textures are wrapped around Cylinders so that the edges of the texture meet at the back. Circular pieces are cut out of the texture and applied to the top and bottom in the same orientation as for the Box.
Again, much the same as the Cylinder, except that instead of a radius field, we have a bottomRadius. This seems completely pointless and unnecessarily confusing to me, but never mind. Also, there is no top field, as cones don't tend to have tops. Normally.
geometry Cone {
bottomRadius 5
height 10
side TRUE #this isn't actually needed, because it's the default.
bottom FALSE
}
Textures are applied in the same way as for cylinders. The default value is a cone of the same dimensions as the Cylinder and Box. The centre of this one is a bit more difficult to visualise. The centre is in the middle, halfway up the cone. Now, when you consider the bounding box of the cone, it seems obvious, but it's not totally intuitive. So, a default cone will extend 1 metre above the Y plane and 1 metre below, having a radius of 1 at the bottom.
A Sphere node has only one field, which is it's radius. Hmmmm, that was easy.
geometry Sphere {
radius 10,000,000
}
That's one very BIG sphere. Anyway, textures are applied by wrapping the texture around the sphere, and then pinching in the top and bottom. So, If you had a texture with a grid on it, the vertical lines would get closer together at the top and bottom, while the horizontal lines would stay the same distance apart all the time.
This node creates some 2D text in the world. It's all very simple really, unless you want to do more complex stuff using FontStyle. The Text node has only four fields. The first is string, where you define the string or list of strings to display. The fontStyle field contains a FontStyle node, which I'll cover in a minute. The last two fields are maxExtent, where you specify the maximum width (in metres) of the text, and length, which is a list of lengths (again, in metres) for each string, so you can specify a specific width for each of them. If lengths are specified, the browser will resize the text to fit in that size.
geometry Text {
string ["Hello", "World"]
fontStyle USE HELLOFONT
maxExtent 5
length [3, 3]
}
OK, that's the Text node then, all very simple stuff. FontStyle is more complex. The best way to start here is to list all the fields.
FontStyle {
size
family
style
horizontal
leftToRight
topToBottom
language
justify
spacing
}
OK then. size is the height, in metres, of the line of text. The family field can take one of three values, and alters the typeface of the font. The three types are "SERIF", "SANS", or "TYPEWRITER". These are all fairly self-explanatory. To change the look of the text, you can use the style field. This can be any of "PLAIN", "BOLD", "ITALIC", or "BOLD ITALIC". horizontal is a boolean value showing whether the text is horizontal ("TRUE") or vertical ("FALSE"). leftToRight and topToBottom are also boolean, and are fairly obvious in their operation. The same utf-8 string can appear differently, depending on which language it is in, so this is a two-character code for the language. I really don't know what the codes are, so it's probably best to ignore this field. justify is very useful, and can be any of "BEGIN", "MIDDLE", or "END". spacing is the amount of space between the lines of text. 1 is normal, and 2 corresponds to double-spacing (a blank line between each line).
That's FontStyle then. You can really ignore most of the fields, but things like the style, family, and justify are very useful.
All the geometry nodes so far ( and all the others we'll meet later on) are centred on the origin of the local coordinate system. When we get onto more complex objects, this becomes more obvious. For now, just remember that the point you position with transforms and so on is the centre of the object. Right then, that's about it for this tutorial then. To see what we've done so far, take a look at Tutorial 4 World and it's associated code.
So, now we have a small monument type thing, topped by a green plastic column with a replica of my head on the top. Groovy. That's all then, carry on to the next lesson, which is a tiny little short one about linking to the outside world. Should be easy...