volumes

A polygon is a triangle (3 sides), a square (4 sides), a pentagon (5 sides), ... up to a maximum of 32 sides.

A volume is made up of several polygons connected together, for example a pyramid, a cube, a cylinder, a sphere, or something more complicated like a marble statue.

When you choose the "Volume" sub-option in the mesh editor, your actions apply only to the clicked volume. It is, however, possible to link several volumes with LINK mode, in which case the actions apply to all these volumes together.

A mesh is made up of several volumes.

How to add several volumes in the same mesh ?
Right-click on the cube you created in the previous chapter and choose the menu OBJECT > EDIT MESH ...

then select the CUBE, CYLINDER or SPHERE mode and click on the floor, even several times : volumes appear then there.

Always keep the window EDIT MESH open and pull items from your inventory into the world : they will be added to your mesh.

To see the drop-down list of all your textures, click on the 1 above the texture image square. You can choose the number of a texture (1, 2, ..) or add a blank one to the list with NEW.

To change a texture, choose the number from the list (1, 2, ..), then click on the square to take a new texture to your PC.

To apply a texture to a volume, go to APPLY TEXTURE mode, then select the texture from the list (1, ..) and click on one of the small pyramids on the volume. You can also choose one of the sub-options (mesh: to change all volumes, polygon: to change only one face etc)

To pull/stretch these volumes, select the MOVE/STRETCH mode, click on the point of a volume and arrows appear. You can choose :

the MESH sub-option to move all volumes of the mesh,
the VOLUME sub-option to move only one volume,
or the ONE POINT sub-option to move only one point.

You can select several things to move or stretch them at the same time, to do this first select the first thing (the dot turns white), then keep the SHIFT key on the keyboard pressed and select the others (they turn white too). To deselect an item, click on it again.

To delete a volume, select the MOVE mode, sub-option VOLUME, click on a point of the volume and then click DELETE.

You can link several volumes together so that they become one by selecting LINK mode, then clicking on several volumes while holding down the SHIFT key. Select the UNLINK sub-option to separate the volumes.

If you've made a mistake, you can always click UNDO to go back a step, or REDO to go forward. Also take a copy of your object in your inventory on a regular basis.

When moving an object, you will notice that sometimes the position arrows are far away from the object. This is because your mesh is not centered in (0,0,0). This is annoying for several reasons:

when you take the object from your inventory it does not appear where you put it but much further away.
the cost of small objects (less than 1 meter) with all textures in phantom material (so no collisions with the avatar) is MUCH higher when they are not centered.

It is therefore recommended that you ALWAYS center your objects.

Some objects are not centered on purpose. For example, doors must be off-center to rotate correctly because the axis of rotation of a mesh is always in (0,0,0).

To center, edit the mesh in MOVE mode, click on any point of the object, then click on the CENTER button.

A centered 1-meter cube has its X and Y coordinates between -0.5 and +0.5, and its Z coordinates between 0 and 1.
Z is not negative, otherwise the object would be half hidden under the ground, which is undesirable.

SEAM mode splits a volume into two volumes.

Mark a dividing line by placing blue cubes all around the volume: you can then work on one side of the seam line without influencing the other side.

To remove all the blue cubes, simply re-link the volumes on either side of the dividing line using the LINK mode.