November 22, 2015 Workshop 19 Notes

PART I: Blend Shapes

Part 1 of this workshop is developed after the on-line tutorials provided in the Robinson Text. For a more complete treatment from within UVA, go directly to the on-line reader and review pages on the Bend Deformer beginning at page 321.

1. Goto to the Surfaces module and create a sphere.
   
   
   
   
2. Make a copy of the second sphere. From the " Edit Menu>Delete By Type" option, select and delete the history of second copy of the original sphere. Make some changes to the shape of the thirds sphere.
3. Go to the Animation Module, select the second sphere, shift-select the third sphere,  shift-select the first sphere , and then to the menu item "Create Deformers>Blend Shape"
   
4. Choose Window > Animation Editors > Blend Shape.
   Go to the blend shape you want to animate, move the target slider,  adjusting the weight of each blend shape to create the transformation desired in the first shape.
   Note that the original shape is deformed accordingly.
5. Use  the "Key" button to set the added shapes with the desired weight at specified frames with the animation.
   
   
   
6. Place the second and third shape on separate layer and turn it off.
7. Playback the animation.

PART II: Use of set Driven Keys

1. Create a sphere and a cone.
2. In the Animation module, go to the menu sequence  "Key> Set Driven Key > Set"
3. Select the sphere, and in the "Set Driven Key" dialog box, go to Load>Select as Driver.
4. Select the Cone, and in the "Set Driven Key" dialog box, go to Load>Select as Driven.
   
   
   
5. Now, connect parts of Drive list with parts of the Driven list. For example, select the "Translate Y" attribute of the sphere with the "Rotate X" attribute of the cone, and set the "key" for each one.
   
   
   
6. Move the sphere up and rotate the cone around the Z axis, and set the key again.
   
   
   
7. Now, move the sphere up and down and the cone is adjusted accordingly. 
8. Finally, key frame the sphere at frame 1, frame 12, and frame 14 and three different positions along the Y axis from its first location in step 5 to its final location in step 6, and playback the animation. Note that the cone is animated as well.
9. Similarly, one can rig a character using the same technique. Using the same methods, the illustration below is developed a with horizontal surface plane rotating around the "X" axis as a driver, and the IK handle on the leg of a skeleton moving up and down along the "Y" axis as the driven. Thus, rotating the horizontal plan drives the up and down motion of the leg.
   
   
   

PART II: Painting Skin Weights

Within the rigging module, create a upper-leg, knee and heel joint.

Create a polygon cylinder coincident with the leg and set the "subdivisions" height to 8.

Attach the polygon as a skin surface to the leg with the menu item "skin/bind skin".

Go into shading mode with the number 5 key.

Select the skin surface.

Select the menu item "skin/paint skin weights" with the check-box also selected.

Select the skin and one of the three joints on the dialog box that follows, and use the paint brush to paint greater or less weight of the joint on the selected areas of the skin surface.

Note that setting a lower weight decreases the influences of a joint on the area of skin painted. Setting a lower capacity decreases the rate at which the weight is applied. For more details see Autodesk on-line documentation on painting skin weights.

PART IV: nParticles revisited (self-colision and size emphasized).

nParticles are capable of self-colision, and therefore can simulate liquid bodies.

1. Make a polygon object that looks like a cup or pail, such as by starting with a polygon cylinder and removing the faces on the top surface of the cylinder.
2. Go to the nDynamics module.
3. Go to menu item nParticles>Create nPartices > Create Emitter
4. Move the emitter so that it is inside the cup and above the cups bottom surface.
5. Select the cup's geometry, and got to menu item nMesh>Create Passive Colider
6. Select the particles, and go to the menu item Fields>Gravity
7. Select a particle, go the the attributes editor icon, open the nParticleShape1 tab, go to the "Collisions" section, and turn on the check-box for "self-Collide.  
   
   
   
8. Go the particle size tab, and adjust the radius.
9. Play the animation for 500 frames and see what happens.
10. Place a polygon plane below the cylinder and make it into a passive collider.
11. Finally, key frame the cylinder spilling over, and see what happens to the particles.