Textures, 1: Drop Shadows

I’ve done a number of posts now about scripting, so maybe it’s time to move on to a new subject. I’m going to assume (as I did with scripting) that you are already familiar with the basics of texturing in Second Life, and also that you are probably familiar with a suitable graphics package for creating or adjusting textures.

Recently I’ve started experimenting with drop-shadows, and on reading Iris Ophelia’s article in New World Notes I see that I am not the only one. Drop- shadows are evidently the new thing!

But what is a drop-shadow, and why would you want one? An illustration is in order. Here is a snap-shot of one of the rooms of my SL home, Morgridge Mansion:

The key thing to note is that in real life there would be an element of shadowing beneath the objects (especially the chairs and the table). Let’s add this in Second Life:

Much better. A nice bit of added realism (to be honest, I’ve slightly overdone some of the shadowing, just to make it stand out for this illustration). You’ll notice that I’ve also added a shadow behind the portrait on the wall.

So…how is it done?

Well, I don’t know how other people do it, but I’ll explain how I achieved the effect.

The first thing you need is a shadow texture. For the Mansion I created two textures, one circular, and one square. I won’t give exact details on how to do this, because they depend on which graphics package you use (personally I use The Gimp, which is free, powerful). If you aren’t familiar with creating textures, I’ve included links to my own shadow textures, which you can feel free to copy and use — see the bottom of this post.

If you want to try creating your own shadow texture, these are the steps that I took. Translate them to suit your own graphics package:

I used a 128×128 graphic (shadows don’t need a high-resolution, so this size is perfectly adequate) with transparency. I then selected an area about 3/4 of the size of the entire graphic, feathered it to about 25 pixels (you can play about with this — it will determine how quickly your shadow ‘fades out’ towards the edges), and used a blend fill of black to dark gray to fill the area. The end result (in both square and circular versions):

(To be honest, I’m not happy with the square version, which has something of an ‘X’ effect to it. More work required, methinks.)

Ok, now we’ve got our texture, how do we apply this in Second Life?

Start with a new prim — cube for square shadows, cylinder for circular shadows. Resize the Z-scale to the minimum, 0.01, and adjust the X and Y scales until the prim is slightly larger than the object that you want to shadow (if you are adjusting the prim using the ‘grab handles’ rather than entering numbers into the dialog, you probably want to scale the X/Y size first, before minimising the Z scale).

You now need a completely transparent texture. There is a transparent texture in the default library, but unfortunately it is not completely transparent, and will leave you with an ugly white edge. I’d avoid it and use your own texture. If you don’t have a fully-transparent texture, I’ve included a link to mine at the bottom of this post.

Apply the texture. Then select the ‘Edit Texture’ option from the build dialog, and select the top surface of the prim. Apply the shadow texture to this surface.

Move the prim so that it is directly beneath the object that is to be shadowed.

On the Features tab of the build dialog, adjust the transparency. The higher the transparency, the more subtle the shadow. I’ve found that a value of between 40 and 60 seems to work best. Experiment.

Link the shadow prim to the main object, and you’re done.

And finally

The transparency of the shadow prim affects the darkness of the shadow, and the best value to use depends on where the object is located. It would be handy to give the owner of the object a way of adjusting this. Here’s a simple script that does just that. Drop this script into the shadow prim. Each time the owner clicks on it, the transparency will increase by 10 (fading the shadow). When the transparency reaches 100, the next click will return it to 0 (completely black):

// Default transparency value. Change to suit.
float transparency = 50.0;
// Amount to change transparency on each click.
float changeBy     = 10.0;
default
{
    touch_start(integer count)
    {
        // Only allow the owner to change the shadow.
        if (llDetectedKey(0) == llGetOwner())
        {
            // Adjust the transparency value.
            transparency = transparency + changeBy;
            if (transparency > 100.0)
            {
                transparency = 0.0;
            }
            // Apply the new value to the prim. llSetAlpha
            // works in reverse to the Transparency value
            // in the build dialog (!), so we'll subtract from
            // 100 to make them match.
            llSetAlpha(1.0 - (transparency / 100.0), ALL_SIDES);
        }
    }
    changed(integer change)
    {
        // Reset the script when the owner changes,
        // otherwise llGetOwner() might return the
        // wrong value.
        if (change & CHANGED_OWNER)
        {
            llResetScript();
        }
    }
}

Downloadable textures

Circular shadow texture

Square shadow texture

Fully-transparent texture