### CAP 203 - Computer Animation III

#### Chapter 11: Special Effects, Chapter 10: Parameter Wiring

##### Objectives:

This lesson covers material from chapters 11 and 10 of the text. Objectives important to this lesson:

1. Raindrops
2. Multiple maps
3. Applying a Decal and Using the Alternative Skeleton
##### Concepts:

Raindrops

This lesson is on pages 224 and 225. This is the author's lesson on rain. She shows us how she makes rain falling beside a window, and how to make appear on the window and run down it.

1. Open the start file for the lesson. You will probably see an error message about not finding a meadow texture file. It does not appear to be necessary for the scene, so just continue.

You will need to zoom out a bit to see the two direct lights the author has put in the scene for us. Let's assume that the window in the room looks north. Look at the Top and Left viewports and zoom out, and you will see that the lights are above and north of the window, angled toward the window by about ten degrees. There is also an omni light in the room.

Open the Light Lister tool, and note the multiplier settings for each light. The omni is set to .5, the direct simulating sunlight is set to 1 and the direct she has named "dapples" is set to .1. (She wants dappled shadows from this light: spotty shadows.)

2. The author says to create a particle system. For those who have not done so, click the Create panel, select the first icon (Geometry), and open the dropdown list. Select Particle systems. There are seven kinds to choose from. The author wants a Spray system. Click the button for Spray. (She creates another type in other steps.)

Drag in the Top viewport, a bit north of the window to create an object that looks like a square. (We will change its dimensions in a minute.)
From the Left view you should be able to see a line pointing down from the center of the square. Move the spray object a little higher than the windows. Rotate it so that its perpendicular line (for aiming the rain) points downward, but at a shallow angle, since rain usually does not fall straight down. In the image on the right, my aiming line is pointed at the window. This is not what you want. The particles from this spray are to fall by the window, not on it.

Right click the spray object, and choose Object Properties. In the lower right corner of the General panel, find the radio button for Object. Click it to select Object Motion Blur, then click OK.

Switch to the Modify panel. Play the scene animation to see the raindrops. (Ignore her reference to rendering the scene, just look at it in the viewports.) Make sure the spray object is selected, or you won't see the rain. Play with the settings under Particles to get a look that works:
• Viewport count - sets the number of drops
• Drop size - sets the particle size
• Speed - sets the rate of flow
• Radio button for Drops should be selected by default

Settings under Emitter can now be changed. Now that you can see the drops, make the emitter (the rectangle) wide enough and long enough to cover the camera view through the window. Again, in this scene, the rain should fall by the window, not through it. In the image on the right, I have changed to a perspective view that a grip setting up this scene might see on a real movie set. The emitter is pointing toward the ground, at a realistic angle, and it is large enough to fool the camera shooting from inside the room.

3. Now the author wants you to create a drop of water, flat on one side, that will be used by another particle system as a texture.

Create a sphere in the Top viewport, then you will be able to model it like hers in the Front viewport as she wants. Looking at her model, set the segments to 12.
Convert to an Editable Poly.
Delete the bottom polygons and cap the hole.
Center the pivot point to the object.
Use Scale on the object to flatten and elongate it a bit. I think she scaled the bottom row of polygons individually. Try that to get the shape she shows in the book.

4. The author wants you to create a PCloud system, which works differently. The Spray system emits particles, like a hose would, from its emitter. The PCloud creates particles either within the 3D space occupied by its emitter, or in a space defined by another object. In this case, it will create particles that appear on the surface of a plane. Carry out the objectives in this step, looking carefully for the properties to change in each case.

5. In step five, she says to create a material for the raindrops. Follow her instruction and add it to the base raindrop you modeled. Ignore the rest of the steps. Her streams down the window are not very convincing. Instead, we will have a guest lesson about raindrops making splashes.

We will continue with two lessons from chapter 10. You need to be familiar with wired parameters for more animation lessons.

Wiring 101

The first lesson we will consider in chapter 10 is Wiring 101 on page 210.

1. Open the start file for this lesson. You should see a bead and a loop. The loop will become an animation path for the bead as well as a scene object. Follow the instructions in the text to apply a Path Constraint to the bead. It does not matter what part of the loop you click, the bead should go into the position shown at the top right on page 211.
2. Move the time slider as instructed. The bead should move on the path. Note that the hole in the bead is not lined up with the loop yet. You will not be able to see the Follow command on the Motion panel until you scroll the panel up. It is on the Path Parameters rollout, under Path Options. Tweak the settings on the Motion, Follow command as instructed to make the bead align with the loop. (Hint: try all three axis settings to see which one is right.)
3. Select the Create panel, the Helpers tab, and the Manipulators dropdown. Click the Slider button. (It is shown selected on page 210. Try a magnifying glass.) On the Parameters rollout (not the Name and Color rollout), name the slider control. Click in the Front viewport to create a slider control. Move it and tweak it as instructed in the text.
4. The slider doesn't do anything yet. Right-click the slider and select Wire Parameters (wire means connect in this case). Examine the popup menus that are displayed in this step on page 210 to see what items to select. Follow the directions to connect the value of the slider object to the percentage of the path the bead has followed.
By the way, you should pause here for a moment. Note that you could have connected the slider to any of the three classic transforms for the bead object.
5. Not done yet. A dialog box should appear, as shown on page 211. This needs a little more explanation. Clicking the right arrow button will set the slider (on the left of the dialog box) to control the bead (on the right of the dialog box). Clicking the Connect button makes it work.
6. Step 6 tells you to click the Select and Manipulate button on the toolbar. It looks like an old-fashioned lug wrench with four sockets. This button allows you to use the manipulator in the scene, as opposed to the Select and Move tool letting you relocate the manipulator in the scene.
7. Turn on Auto Key, but don't forget to move the time slider before making a change that sets a key. Save your file. Render an animation of it, and show it to me.

This exercise is on pages 212 and 213.

1. In step 1, load the scene file, which has a loop and four beads in it. Note the description in the text: the first bead is wired already, and each of the beads is separated by a specific interval from the ones next to it.
2. Step 2 will look familiar, but it is different as well. Compare it to step 4 in the exercise above. This time you are setting a property for two beads. Follow the instructions in the text.
3. Set the dialog box settings as instructed in the text.
4. Animate with the slider to test the work so far.
5. Continue to set up the third and fourth beads.
6. Save your file, and open the second file for this lesson. Note the pitfall described in the text and its remedy.
If you allow the first bead to move to position 0 on an open path, the other beads will be forced to the opposite end of the path by bad math. Correct this problem by setting a minimum path value for the first bead that allows the other beads to be remain on a logical part of the path.
This problem does not exist in the BeadsFollow.max file supplied with the text. To see the problem, you will have to select the Slider object, choose the modify panel, and change the value for Minimum to 0.
Do this and then demonstrate the problem version of this file. Save this version of the file incrementally.
Note: this is not a problem if the path is circular, or any other shape that is a closed loop. It is only a problem is the path is not a closed loop.
7. Render animations of the beads moving across the circle in the first file, and each way (good and bad) in the second file, and show them to me.