Making Waterfalls in WorldBuilder 4
In this tutorial, we will cover the basic theory and application of one of Worldbuilder’ s most interesting features: the Waterfall tool.
Note: This tutorial is designed to be used with all versions of WorldBulder 4, including the downloadable Demo version. Because certain features such as file and image saving are disabled in the demo vision, sample project files have been provided for download and review. If you are using the demo version of WorldBuilder 4, you will still be able to follow along and render non-saveable still images.
Let’ s get started.
Open WorldBuilder 4. The default project file includes a Landscape object, a Camera and one Directional light. If you wish to, you can create a few Skeleton Lines of your own, or use the ones included in the sample file Waterfall_Start.awb.
In the Creation Toolbar, select the button for the Waterfall tool. The cursor will change to placement mode.
Click in the Top Viewport. The Waterfall object will appear in the workspace and in the Scene Tree.
Notice that the Waterfall is oriented along the X-axis. You may need to Rotate it in order to align it with your Landscape elements.
The Waterfall object is a specialized particle emitter.
It sprays its particles in a very thin horizontal line. This stream of particles should be visible in your Viewports. The 3 parallel arrows near the emitter also indicate the particle direction.
The longer vertical and horizontal arrows control direction / strength for its Gravity & Wind variables; these can be accessed through Worldbuilder’ s standard Manipulator feature.
Depending on what kind of waterfall you want to make, you may need to adjust its Scale.
Choosing the Scale function from the Manipulator or the overhead menu toolbar can do this.
Notice that the Scale affects only the width of the Waterfall’s emitter.
Worldbuilder’s particle engine can produce some extensive redraw times. To save ourselves some time, let’s adjust one of the Waterfall’s Settings variables before proceeding.
In the Property Tree, select Settings.
Change the Particles per Frame value from 100 to 1. This will reduce the amount of calculations Worldbuilder will have to perform every time it updates its display in response to a given changed variable.
(As an alternative to resetting the Particles per Frame variable, you can also disable/enable the draw in wireframe mode feature; this will make the particles invisible until render time.)
While we’re still in the Settings Properties panel, let’s change Live Time from 40 to 80.
Reduce Visual Size from 5 to 0.5.
If you want to see your particle stream in your workspace viewports (and don’t mind sitting through some redraw time), enable the Draw in Wireframe Mode check box.
Note: If you are planning (eventually, someday) to display your WorldBuilder scene in NTSC or ‘D1’ format, then set the FPS (Frames Per Second) parameter to 30. If you will be displaying in PAL format, use the default value of 25.
Later on, you’ll set Accuracy to a higher value. Don’t do this until you’ve fine-tuned your waterfall scene; higher Accuracy values make better Collision and Physics interactions but also extend render times.
Now let’s go to the Physics Properties panel. Note that the Gravity value corresponds to the speed at which the water particles fall away from the emitter. Its default setting of 10 is probably sufficient for a large waterfall like ours (slower movement suggests more mass and larger scales), but you may want to adjust this value even further downwards.
Gravity can be adjusted numerically in the panel, or interactively by using the Manipulator and the waterfall’s vertical arrow (make sure the Draw check box is enabled).
In the Emitter Properties panel, set the Velocity to 7.5. This setting should be adjusted in conjunction with the Gravity setting. Remember, the higher the value, the faster the particles will move.
Add a small ‘+/-‘ variation value of 2.5.
This will keep the particles from moving at exactly the same rate, which in turn will enhance your scene’s realism.
Let’s do a test render, to see how our settings are being applied to our scene.
In our example Scene file, we’ve added a River (See the River tutorial for more information on making River objects).
Now would be a good time to make our waterfall interact with some of these new objects.
In the Properties Tree, choose Collision Objects. In the Property Page, select Landscape0 and River_0.
With our collision objects assigned, let’s go to our Waves property.Select your river object
Now our waterfall will disturb the surface of the River in an appropriate manner, with waves spreading out from where the waterfall strikes it.
You can use the settings shown for Probability, Amplitude and Radius, or you can experiment with your own settings.
Before re-rendering the scene, let’s adjust the Settings property again.
Increase the Accuracy value to 8.
Increase the Particles Per Frame value to 200.
Also, set Motion Blur to 1.
Now, let’s re-render the scene. Keep in mind that these settings will increase your render time.
Now that we’ve created interactive waves, and adjusted our Settings, let’s enable another property for our waterfall. This property will create vaporous emanations around our wave zone.
Make sure the Splashes property is set to ON (right-click to uncheck Disable).
In the Property Page, leave the Probability and Live Time parameters at their default settings. We do, however, want to change the Start and Final values for Size, Opacity and Height. If we use these defaults, our render times will increase dramatically and our waterfall will be obscured by the splashes.
Set Size: Start to 1, and Size: Final to 4.
Set Opacity: Start to 0.2.
Set Height: Final to 4.
Let’s re-render the scene with Splashes.
If your scene doesn’t look quite like the rendered image shown here, download and open the zipped sample file Waterfall_End.awb.
If you want to see the waterfall in motion, download and open the zipped file Waterfall.avi.
This concludes our Waterfalls tutorial. Good luck, and happy WorldBuilding!
