Describes: restricting brushmaps and textures to surfaces, surface extents, object normalization.
In the last two tutorials we often stated that brushmaps and textures are applied onto the Surface bound box. That is, they assume that the range -1...1 in all the three axes is given by the Min and Max extents of all the points that belong to the Surface the brushmap or texture is applied to.
The Surface bound box is created when the surface is created and can not be displayed in the editor. Apart from this it is conceptually similar to object's bound boxes. For objects that are composed of only one Surface, like the ones we used so far, the object's and surface's bound boxes coincide. When an object has more than a single Surface, the bound boxes are different. To see how, add a polygonal plane to the editor and load a brushmap. Assigning the map to the object would result in the same imagery we saw in previous tutorials. So enter Face mode and select only the polygons in the left half of the plane.
White polygons represent new surface's bounds
Now select Modify> Surfaces> Make Surface or press Amiga-M to open Make Surface Panel. Here you can choose to add the selected polygons to an existing surface (selecting its name in the list view, then Accepting the panel) or to create a new surface hitting return in the Name gadget or using the Add gadget if the default name pro vided by Tornado3D is adequate. It is strongly suggested to use complex, descriptive names for surfaces.
DEFAULT is the surface every object starts with
Change the Surface_01 name into "Left" and hit return. The surface will be added to the list. Close the panel clicking Accept. Now there are two surfaces, one named Left that refers to the polygons we selected, and the old one named DEFAULT that holds the remaining polygons.
Enter Materials Panel (you can do so without return ing to Groups Mode) and apply to DEFAULT surface the brushmap. Previewing will show that only half of the polygons, those belonging to DEFAULT Surface, are textured and that the entire brushmap is fitted to the surface area.
The brushmap fills "DEFAULT" Surface bound box
This means that if the surface we are working on covers one half of the entire object, then the texture or brushmap applied to it will appear to be one third smaller than if it was applied to the entire object, yet it will depict the same basic image the bigger one would have depicted.
Now select half of the polygons that still belong to DEFAULT Surface and open again the Make Surface Panel without creating a new surface. Instead, select "Left" from the list and accept the panel so that more polygons are subtracted from DEFAULT Surface.
Again, this acts also a visualization of bound boxes
Instead of rescaling the brushmap to fit the entire DEFAULT area, Tornado3D will now ignores the missing polygons applying the map to the old bound box. This is intended and allows for "restricted application" of textures as well as for texture and maps animation. That's also the reason why it is suggested to apply maps and textures only after that geometric modeling is complete.
DEFAULT Surface bound box is not altered because the map was applied before modifying the surface
If Surface's geometry is altered after applying the texture, the Modify> Surface> Recalc Textures menuitem is required to re-normalize the application to the new Surface Bound box. Go in group mode and use Modify> Surface > Recalc Textures to see the effect. Now the image in DE FAULT Surface is again constrained to the smaller bound box.
The normalized surface again shows the entire image