Object Display in the 3D Preview
Terragen is able to display objects in the 3D Preview in various different ways. These are the different display modes which can be used:
This hides the object. It's bounding box and/or manipulation handle will still be drawn but not the actual object itself.
This displays the bounding of the object.
This mode displays the object as wireframe. Only the outlines of the object geometry are drawn. Approximate shading is drawn, which depends on the sun position.
This mode draws the geometry as filled polygons. They're smooth shaded using the sun position to calculate approximate shading.
This mode is essentially the same as smooth shaded, except that the object textures are also used if possible. TG can currently only generate textures for use in the preview from a few simple material/texture configurations. Image map based textures imported with models will usually work. Procedural textures cannot be shown in the preview yet.
Object display modes: Bounding box, wireframe, smooth shaded, textured (click for larger)
A combination of two factors control how objects are actually drawn in the preview. The first is the Preview mode parameter for each individual node. This is normally near the top of the node parameter view. This parameter sets the most detailed mode the node can be previewed with. The default setting is "Textured". What is actually drawn depends on the second factor, which is the object display mode of a 3D preview.
The object display mode of the 3D Preview is set using the Object Display Mode button. This button is in the top 3D Preview toolbar and has a blue box icon. Click the button to choose from the different detail settings for the preview. This sets the most detailed mode the 3D Preview will display. By default it's set to bounding box.
Here's an example of how these two factors combine to show what is displayed in the 3D Preview. Let's say we've loaded a new plant object into the scene. By default the Preview mode for the plant object is set to "Textured". However the 3D Preview is set to "Show as bounding box" by default. The object will be displayed using the least detailed of the two display modes. In this case the object will be shown as a bounding box because that's the least detailed mode.
If you change the 3D Preview object display mode to "Show as textured" you will see the object drawn with full textures. Now go to the object's node parameter view and change the Preview mode param to "Wireframe". Notice how the object now gets drawn as a wireframe in the preview even though it's set to "Show as textured". Once again this is because the least detailed of the two settings is used.
Although this might seem a little complex it does give you a great detail of control over how objects are displayed in the preview. It allows you to have all your objects displayed with the best setting for the purpose while still allowing you to quickly drop all objects back to a certain detail level via the 3D Preview object display mode without having to make changes to all the objects individually.
There are some other ways you can set the object preview mode in addition to using the Preview mode parameter. The first is to context click on the object handle in the 3D Preview. There is an "Object Preview Mode" menu in the context menu which lets you choose the preview mode for the object. This menu actually has additional options. For example it lets you display an object as wireframe with a bounding box. You can also use the Action button in the Objects node list. For more about this please see the "Changing Preview Modes for Multiple Objects" section below.
Most objects have a Preview colour parameter. When this parameter is turned on objects are drawn in the preview using the specified colour. You might want to use this to make a particular object stand out in the preview.
Both the bounding box and object itself are drawn with the preview colour. When the object is textured the preview colour tints the texture colour.
Populations have a few differences in the way they draw in the preview. One of the most important ones is that you use the Preview mode of the population node to control how population instances are drawn. It overrides the Preview mode of the object node being used by the population. If you change the Preview mode of the object you won't see any change when the population is drawn.
Populations are drawn using a level-of-detail system to enable drawing many objects at the same time. For wireframe, smooth shaded and textured modes any instances that are further than a certain distance from the camera are drawn using billboards instead of the full object geometry. Instances that are even further from the camera are drawn as points in all display modes, including bounding box.
Changing Preview Modes for Multiple Objects
You can make changes to the preview modes of all objects at once. At the bottom left of the Objects node list is the Action button (with a gear icon). The menu for the button lets you perform actions on all the objects in the project. For example it has a "Set all objects to wireframe" option. If you choose this the Preview mode parameter for all the objects will be set to wireframe. This is different to changing the object display mode for the 3D Preview, which will make all the objects draw in wireframe without actually changing the object node settings. Using the Action button menu is the same as going to every object and changing the appropriate parameter manually.
It's important to note that the different display modes do not necessarily correspond to a certain level of performance for the 3D Preview. For example although the "Textured" mode is the most detailed it may actually draw more quickly than the "Wireframe" mode. This is due to some characteristics of modern graphics cards. From this perspective it's probably best to choose the display mode which suits you at the time rather than worrying about performance. One exception to this is that the bounding box mode will usually be the fastest.
If you find the 3D Preview is getting a bit slow and you have a number of populations you might try turning the Preview mode for one or more of the populations to "Hidden". This will hide the instances of the population but still show its bounding box and manipulation handle.
The bounding box is a box which surrounds (or bounds) an object or shader. This box shows the maximum extents of the item inside it. Sometimes abbreviated as "b-box".
A parameter is an individual setting in a node parameter view which controls some aspect of the node.
A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.
In a graphical user interface (GUI) on a computer a toolbar is a row, column, or block of onscreen buttons or icons that, when clicked, activate certain functions of the program.
Context clicking shows a contextual menu. On Windows this would normally be done with a right click. On OS X this could be a control-click or a right click.