Exercise 8 - Adding a Liquid
In this exercise we'll add a swimming pool to our level.
Building the Pool
Draw
a 3" by 4" rectangle on the ground near the end of the long corridor,
and pencil off four 1/2" slices from the sides. Pull an extension out
from the corridor to meet up with it. Use the Push-Pull tool with the
Option key to pull everything up to a height of 1".
Before going any further, check the underside, as some of the faces may be the wrong way up. If so, select them and choose Reverse Faces from the contextual menu.
Open it up and delete all the interior faces.
Pull the centre area down a distance of 3/4".
Apply some textures.
You
may want to export and play the map now to check that everything is as
expected. You should have a nice, empty pool, waiting for some water to
go in it.
Adding the Water
Open
up Objects.skp and copy the blue cylinder into your model. This is
another placeholder object, this time for a liquid. Take a look at it
in the Components window and you'll see its description is set to *Liquid.
The horizontal position of the liquid object doesn't matter, but the height
of the liquid is determined by the position of the top of the liquid
object. Move it downwards until the bottom of it is in line with the
bottom of the swimming pool. The object is initially 1/2" high, so that
will bring its top 1/4" below the top of the pool.
Select the cylinder and choose Plugins>Marathon>Object Properties. Set the name of the liquid to "Water".
Now select the bottom face of the pool area and bring up the Polygon Properties. Set the Liquid to "Water".
Export and play the map, and the pool should be full of water!
Swimming isn't recommended, since if
you jump in the pool, you won't be able to get out. Adding
some steps leading out of the water is left as an exercise for the
reader. Remember to set the Liquid of all the step polygons that you
add to "Water" as well.
Water Effects
The
water sounds good, but it looks a bit static -- it could do with some
ebb and flow.
Flow
You can give the water a current by entering a
value for the Flow Speed in the Liquid Properties window, in world
units per second. The direction of flow is controlled by the
orientation of the liquid object, as indicated by the arrow on top.
Tides
We can use a light to control the tide
level of the water. Add another Light instance from the Components window. Open its Object Properties window, set its name to "Tide", and fill in the values below.
When
a light is used to control the height of a liquid, intensities of 0.0
and 1.0 correspond to the bottom and top of the liquid object
respectively. So with the liquid object positioned and sized the way we
have it, a range of 0.75 - 1.0 should make the water bob up and down
just near the top of the pool.
Select the liquid object again, open its Object Properties, and set its Tide Control to "Tide".
Export
and play the map, and the water should now be gently rising and
falling, and if you've set a flow speed, it should also be flowing in
the direction you indicated
Lighting
Another trick you can try is setting the Liquid
Light field of the pool's Polygon Properties to "Dim". This will make
the surface of the water dimly lit when the lights in the corridor are
out, even if the rest of the room is bright!
In Exercise 9, we'll add some sounds to our level.
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