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Class 3: Copy and Link Multiple Prims

Up to now, we have only worked with one prim - changing its shape, moving it and adding colour and texture to it.

One-prim objects are very, very prim-efficient, but when you build an object, you are usually going to use more than one prim.

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Use Shift-Drag copy method

All these terms refer to exactly the same thing -copying a prim using the Shift-Drag Method.

To copy an existing prim, first you have to select it. You can tell if the prim you want to copy is selected as it has a yellow outline.

Selected Prim

This yellow outline is visible when you are in Edit mode, so right click on the prim and select the Edit option from the pie menu to go into Edit mode and open up the Edit window. Don't forget to open the Edit window fully by clicking on the More>> button.

If you recall from the previous lessons, to move a prim you place your cursor over one of the red, green or blue arrowheads, hold down the left mouse button and drag the prim in the direction of the arrow.

The Shift-Drag copy method uses EXACTLY the same process, except that you first press the Shift key on your keyboard, THEN drag the prim in the direction where you want the copy to appear.

Shift Copy a Prim

The Shift Drag copy method creates an exact copy of the selected prim, including any textures, colours or scripts that you have added to it. (Of course, you must have copy permissions on any textures or scripts that you are trying to copy).

Benefits:

One of the most appealing benefits of using this method to make a copy of the prim is that the 2 prims are now perfectly aligned on 2 of the 3 axes.

Test this out for your self:

Note down the X, Y and Z position numbers of the original prim.

Now Shift drag a copy of this prim in any of the red, green or blue directions.

Now look at the position numbers of the second prim.

If you dragged your copy along the blue line, the X and Y Position numbers are the same; if you dragged your copy along the red line, the Y and Z Position numbers are the same.

Two thirds of the prim alignment task has already been done for you!

A second benefit is that if you have textured your first prim, the copied prim also inherits the textures and colours of the first prim. That's another task you don't have to worry about.

You can also select multiple prims and Shift-Drag copies of them; once again, these prims will be perfectly aligned on 2 axes relative to the original selected prims.

Select multiple prims to copy via shift-Drag

Hint: Say you want to align 4 legs to a table top; you will rez and align the first table leg, shift-drag a copy of the first leg to the other side of the table, then select these 2 legs and shift-drag 2 more copies and place them on the other side of the table. In 3 moves, you have created 4 aligned table legs.

One Prim Buildng Method

The "One Prim Building Method" uses this Shift-Drag copy method to assist in the alignment of prims when building. I have seen this technique used in 2 different ways:

  1. Rez the first prim, texture it, then rez 2, 3... multiple prims above the original prim so that you have a column of textured prims. Now you can work on each prim to modify it then lower it into position. Take care not to move any of the prims in the X (red) or Y (green) directions when you use this method.
  2. Rez the first prim, modify and texture it as required, then Shift Drag a copy, modify and align it, then Shift-Drag a copy of either the first or second prim and so on...This method allows you to Shift Drag a copy of whichever completed prim you want to use.

Both building methods are equally valid and can be used to build and give you exactly the same completed build results. Use which ever method you prefer to use and feel free to switch between either method as you require.

Negatives:

Of course, there is a slight downside: you can't Shift-Drag a copy of a prim that is already linked to other prims (see below for Linking information). If you need to make a copy of a linked prim, you will need to Unlink the prims of the current object, then Shift Drag as per above steps, then re-link the prims for the original object.

In some situations this unlinking-relinking method will be useful for you, other times unlinking prims will cause more problems; you need to determine which method to use based on your building needs.

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Use Ctrl + Z (or Cmd + Z) to Snap Back

The Ctrl + Z (Cmd + Z on a Mac) is also sometimes called Snap Back:

"rez a cube, shift-drag a copy to the left, then snap it back" In this example, the Ctrl + Z function behaves in a similar manner as it does in other external applications - it "undo's" the move of the previous action.

Your copied prim is perfectly aligned on all 3 axes: the X, Y and Z position numbers are all identical. You can now continue making changes to your prim and take advantage of this alignment shortcut.

The snap-back action can also be used to Undo the previous move of the current selected prim. If you have accidentally moved a prim, press Ctrl + Z/Cmd + Z (Mac) to undo the move. This is a sanity-saving move if you have just spent a lot of time getting your prim aligned perfectly, only to 'bump' it out of the way

You can move several prims out of the way to work on a particular prim, then use the Ctrl +Z on the moved prims to return them to their original position. Its even good for "what-if" scenarios such as: "what if I moved the lampshade prim up an bit and rotated the light bulb prims at 90 degrees?" If you decide you don't like the changes you have made, select each prim and use Ctrl + Z to move them back to their original position.

You can Undo several moves via the Ctrl + Z action, so be careful you don't undo too many of your changes!

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Link and Unlink Prims

Once you have modified your prims and aligned them to create your object, you will want to link them so that they stay in their current position. It is also much easier to Take and Move an object if the prims are all linked; you won't be leaving any prims behind.

Before you can link, you need to select all the prims that you want to link. You may want to link all the prims in your current object, or link them in separate groups.

Of course, you can only link if more than one prim is selected :)

Selecting Multiple Prims

Option 1 is the select each prim one-by-one way: select a prim, hold down the Shift key and click on each additional prim to select additional prims. Each selected prim will have a yellow outline as you add them to selected group of prims.

This is a quick and simple method if you have large prims that are easy to see and select.

Option 2 for selecting prims is to Select by Surrounding. Activate this option by selecting it from the Tools menu: Menu -> Tools -> Select By Surrounding. To quickly select the prims you want to link click the area just outside the upper left section of your group of prims, hold down the left mouse button and DRAG a Selection box around the prims you want to select for linking. (Very similar to selecting a section of text in a document). All the prims you have selected are now outlined in yellow.

Select all Prims to Link

Whoops, I seem to have selected every prim within a 50 metre radius of my prims - what do I do?

If you do accidentally select other prims that are not your own, don't worry! SL will not allow you to include prims that are not your own when linking i.e.: prims that you do not have permissions to modify.

To make sure you only select your own objects before you try to link, select and place an X next to the Select Only My Objects option from the Tools menu.

Once you are satisfied that you have selected all the prims you want to link, you can use either of the following methods:

All the selected prims will now have a blue outline, except one prim which will still have a yellow outline. The lone prim outlined in yellow is the Root Prim

Linked Prims

Root Prim

The Root prim is the last prim you selected before linking. If you used the Select By Surrounding method to select prims, you probably couldn't control which of the prims was selected last. Simple to fix.

While still holding down the shift key, click on the prim you want to be the root prim to de-select it, then click on it again to re-select it; this is now the last prim selected, so when you press Ctrl + L to link, the root prim highlighted in yellow will be the last prim you just selected.

The Root Prim has some special characteristics:

In many situations there is no relevance or importance in which prim is the root prim, while in other objects, the root prim plays a crucial role. One example is where a script will only work correctly when it is included in the root prim - e.g. the swing script for a hammock must be in the root prim for the whole hammock to swing as one object, otherwise only the prim with the script in it will swing.... only the rope?.

Unlink Prims

If you have missed a prim when linking, or need to change the root prim, or no linger need to have your prims linked, you can unlink them using any of the following methods:

You can also combine the above linking methods with soft links to create your object.

Soft Links are where you have selected multiple prims, but do not Link them; instead, you just Take them to your Inventory. You will notice that the icon next to this object in your Inventory folder is different;

Ready to test your linking skills?

This is the scary moment of truth: select the linked object, click on an arrowhead and move it in any direction. Did you link ALL your prims, or did you leave any behind?

If you did accidentally miss a prim when linking, you will need to Unlink them, hold down the Shift key as you select the forgotten prim/s, then re-link.

Don't forget to use Ctrl + Z to undo the move of the linked prims before you start unlinking!

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Edit Linked Prims

Now that you have all your prims selected, you may need to make additional changes to one or several of the linked prims. You cannot edit a prim while it is linked to other prims; when you try to select a specific prim, you always select all the prims.

One option is to Unlink the prims, make the required changes, then Re-link

An alternative is to use the Edit Linked Prims functionality via the Edit window.

Locate the Edit Linked Prims check box and tick it to activate it.

Edit Linked Parts option

Now when you click on a specific prim, you will notice that only that prim is highlighted in yellow.

Go ahead and edit your prim as required. when you have finished making changes, don't forget the de-select the Edit Linked prims option from the top of the Edit window again.

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Project: Simple Coffee Table

Click on the image link to go to the project instructions.

Simple Coffee Table


Next Class: 4. Use Grid Rulers to align Prims

Class: 2. Texture and Colour Prims