Topic Summary:

  1. Introduction
  2. Select By Surrounding
  3. Highlight Transparent
  4. Phantom Objects
  5. Making Plants with Transparent Prims
  6. 3D Effects for Plants
  7. Class Project: Make a Pot of Flowers

Class 5: Working with Transparent Prims


We have learnt in previous classes how to shape and texture prims to achieve our final object.

The textures we use play a large part in the final look and feel of object we are creating.

For some objects the texture we want to use has a transparent background, also known as an alpha channel.

The transparent background make the prim totally see through where the transparent parts of the texture are located.

For example, a one-prim wall with a window where the texture where the glass of the window is located is transparent and allows us to see through the prim to the other side.

A prim can be totally transparent, or have a transparent texture applied only to one side. For example, a one-way floor to ceiling window prim.

Shoes in SL usually have transparent prims shaped and places around the heel and sole area that are used to hide some parts of the avatar's feet that stick out of the the shoe - aka Invisi-prims

Textures used for plants usually have transparent edges outside the plant sections of the texture. So when you apply a rose texture to a flat rectangular prim, the only portion visible is the stem and rosebud images on the prim, the rest of the prim is transparent to the user.

The prim is still there, its just not visible, so an avatar trying to walk near a transparent prim may become obstructed the prim that is still there.

Some builders use the Phantom feature, located under the Object Tab, to make their prim a phantom object; you can see it, but you can also walk right through it.

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Select By Surrounding

Working with Transparent prims can be a challenge as, well, you are working with an invisible prim :)

While the prim is selected, it has a yellow outline and you are able to see where it is located, but if you de-select the invisible prim, there are no yellow edges to see and it truly becomes invisible.

Select By Surrounding

To find your lost prim you will need to use the Select by Surrounding technique to find your prim.

As with selecting multiple prims, you can select them by clicking in the top left corner of the area where they are located and DRAG a selection rectangle around them.

You use the same technique with lost invisible prims by selecting a large rectangle around thew area where you think the prim might be.

You can activate this option from the Tools Menu

Menu Selection Select By Surrounding

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Highlight Transparent

A MUCH easier technique to use when working with transparent prims is to activate the Highlight Transparent option that is located in the View Menu

Highlight Transparent menu Option

When you select this option, ALL transparent objects and transparent textures take on a red tone that makes them easy to see while you are working on them.

Create a Vase

(also a good way to see if there IS something in front of you that is blocking your avatar)

A bit of a side note: Highlight Transparent will show ALL transparent objects and textures around you, including transparent attachments worn by other avatars, so take care where you point your camera :)

You can leave the Highlight Transparent option turned on while you work, or turn it on and off as you require it while you build. Use whichever setting assists you with building your object.

Create a Vase

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Phantom Objects

Prims that are phantom are visible, but your avatar can walk right through them as if they weren't really there.

So, with the previous example of plants that have transparent edges to them, if you make them Phantom, then any avatar walking nearby will be able to walk through the leaves and branches without any hindrance.

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Making Plants with Transparent Prims

You build plant objects in SL exactly the same way as you build any other object. The only difference is that the textures we use for plants have transparent portions on them that require some additional care when working with them.

Newbie Builder Alert: the most obvious way to give away the fact that you are a new builder is to have dirty edges on your builds that use transparent prims. Dirty edges on transparent prims SHOUT newbie builder!

What do I mean by dirty edges? The image below shows an example of a prim textured correctly, and one with dirty edges.

Create a Vase

Dirty Edges

When we texture a prim, we usually apply the texture to all the surfaces of a prim.

Testure all sides of a prim

To make 3D plants, we need to flatten the width of the prim as much as possible to give it a flat effect.

If you apply a texture to the whole flattened panel, it will also be applied to the 4 narrow edges of the prim as well as the 2 large surfaces. This squashed texture is still visible on the edges of the transparent prim, making them look dirty.

Dirty Edge of a Transparent Prim

To avoid this effect, you will need to texture your plant panel in 2 steps:

  1. make the whole prim transparent by applying a Totally Clear texture
  2. apply plant texture ONLY to front and back of prim panel, not the 4 narrow edges.

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3D Effects for Plants

To give your plant object the 3D effect via a 2D object, you would usually make 1 or 2 additional copies of the first plant textured prim and rotate the prims at regular segments along the Z axis to create the 3D illusion.

Create a Vase

Additional features you may decide to use to give your plants a realistic effect include making them Phantom (Object Tab) or Flexible (Features Tab).

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Wrap Up

Working with transparent prims is no more difficult or complicated than working with regular prims.

SL provides you with the Highlight Transparent and Select by Surrounding tools to assist you when building.

Now, click on the image link below to go to the Pot of Flowers project where you will practice working with Transparent Prims.

Pot of Flowers

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Next Class: 6. Flexi Prims

Previous Class: 4. Camera Controls