108 Animating Real-Time Game Characters FIGURE 3.25 Assign all the upper arm vertices to the UpperArm link. (think knee and thigh). Vertices that are farther above the elbow will be less influenced by the forearm, and vertices below the elbow will be less influenced by the upper arm. FIGURE 3.24 The Initial Skeletal Pose option helps you go from an animated to unanimated state. Chapter 3 Weighting a Character Using Manual Vertex Assignment 109 Whenever it's a certainty that two links will be influencing a set of vertices like the elbow, go ahead and assign them all an equal weighting (1 to the parent link and 1 to the child link). Of course, these values won't stay that way for all the vertices, but it's a quick way to assign them to the right links simultaneously, causing the default Currently Assigned Links Only to be a boon and not a handicap when tweaking the values. Zoom in on the elbow area, and only select those vertices that make up the elbow. Bring up the Type-In Weights dialog box, click All Links, and assign the vertices to Betty R Forearm by clicking on it and typing in 1 (the vertices will turn dark green). Toggle Initial Skeletal Pose back and forth by unchecking and checking its box to see the effects the weighting change has on the elbow (Figure 3.26). FIGURE 3.26 The elbow here has equal influence on both the UpperArm and Forearm links. Unfortunately, the Forearm link does not immediately follow the UpperArm link in the Type-In Weights dialog box. Several links that are children to the Forearm appear first. Be careful not to accidentally assign weighting to a Hand link when you think you're assigning it to the Forearm (Figure 3.27)! While the weighting doesn't look bad, giving all of the vertices equal influence from both links detracts from the intent of the geometry, which 110 Animating Real-Time Game Characters FIGURE3.27 Beware the confusing out-of-order Forearm link. is to portray a thick elbow pad. Therefore, a few adjustments need to be made. By toggling the Initial Skeletal Pose box on and off, you can get a rough feel for what the values of the vertices should be changed to. For example, the vertices at the top of the elbow need to be influenced less by the forearm so the elbow can retain more of its shape, but the vertices at the bottom of the elbow don't need to be changed as much. Turn your Initial Skeletal Pose back on, and try the values shown in Figure 3.28 for the elbow area. Now when the elbow is bent, it looks better and keeps the shape of the elbow pad intact. (Figure 3.29). That solution solves the problem with the back of the elbow, but the front of the joint (the bottom of the bicep area) needs to be tweaked as well. With a weighting of 1 and 1, the arm crimps enough to make the bleep shrink, instead of remaining the same or bulging. However, if you bias the vertices more toward the UpperArm link, the forearm geometry will look strange (Figure 3.30). A solution to the forearm deforming the way it does is to lessen the contrast of the elbow juncture; transfer some of the influence from the forearm vertices over to the UpperArm link. It doesn't have to be much, and can vary from character to character. Select the three vertices at the top of Betty's arm in the bent position, lock them, and add the Betty R UpperArm link to the links that influence the vertices. A value of 0.1 should work fine (Figure 3.31). Chapter 3 Weighting a Character Using Manual Vertex Assignment 111 FIGURE 3.28 The elbow needs to be biased more toward the UpperArm link. FIGURE 3.29 The elbow looks better with the new weighting values. 112 Animating Real-Time Game Characters FIGURE3.30 Biasing the front of the elbow joint to the UpperArm link causes a strange deformation. FIGURE 3.31 Adding the UpperArm link to links that influence these vertices helps deform the forearm better. Chapter 3 Weighting a Character Using Manual Vertex Assignment 113 This juggling of weighting influence between adjoining links is neces- sary to get around the limitation, which is a drawback of most generic weighting algorithms found in most programs like Physique. Only with a true "sliding skin" weighting system can areas like elbows, knees, wrists, ankles, necks, and even shoulders and hips be 100 percent accurate in the deformation of polygonal skin. However, keep in mind that this only applies to real-time games; movies featuring CG-rendered characters em- ploy all kinds of complex skeletal and musculature algorithms to simulate skin and muscle movement. Working on the Hand and Fingers While most real-time game characters have mitts for fingers and clubs for fists, Betty has the full use of five digits on her right hand. The weighting for wrists is somewhat similar to that for ankles; select the vertices at the joint, and give them equal influence by both Forearms and any of the in- ternal Hand links. To avoid too extreme a deformation at the wrist area, sometimes it's a good idea to build your character with the palms facing forward instead of downward. This may be as simple as turning the hand geometry, and then turning any bad edges (Figure 3.32). The fingers need to share influence between links at the knuckles. Starting at the end link of the finger, and working your way towards the FIGURE 3.32 Sometimes it's the geometry rather than the weighting that needs to be tweaked to ensure proper deformation. 114 Animating Real-Time Game Characters hand, select and assign the vertices to each link along the way (including all knuckle vertices), locking them as you go (Figure 3.33). FIGURE 3.33 Assign the vertices of the hand by starting with the fingers. As you can see in Figure 3.33, the vertices highlighted in Group 1 are assigned to Link A. Vertices in Group B are assigned to Link B, and those in Group 3 are assigned to Link C. The quickest and easiest way to com- plete the weighting is to go back and select only the knuckle vertices, and share influence with the link that is the parent of the assigned link. Whenever the Type-In Weights dialog box is brought up and All Links is chosen, the link to which the selected vertices are assigned will automatically be high- lighted, to make it easier to see against all the other links. However, when the link selected is far enough down the overall list, character studio displays it by dropping it to the bottom of the display window. By assigning vertices to the end link of the fingers, and moving inwards towards the parent, the parent link that needs to share influence over the vertices selected will be visible and on top of the selected link when the list of links is displayed. If the vertices had been assigned to the par- ent first, the child would be below the displayed list, and you would have to scroll down to see the child of the selected link (Figure 3.34). Chapter 3 Weighting a Character Using Manual Vertex Assignment 115 FIGURE 3.34 When typing in values for a parent-child set of links, assign the vertices to the child first, not the parent. Character studio duplicates the naming of links so that each character can have a number of Hand links. The best way to tell them apart is to look below each link in the list of links. For Betty's uppermost knuckles, share influence with the Hand link above the link the vertices have been assigned to. Often, when weighting vertices by hand, you 'II select a set, enter their values with the proper links, and then select another set, keeping the Type-in Weights dialog box open all the while. One quick way to isolate a link when "offscreen" is to toggle back and forth between displaying All Links and Currently Assigned Links Only. Doing this immediately lines up the selected vertices' link at the bottom of the long list and saves you from scrolling up or down to find it. For the thumb, rotate your view so you can see it in profile, and se- lect and assign its vertices (Figure 3.35). All the vertices in Group 1 are assigned to Link A, Group 2 to Link B, and Group 3 to Link D. Share influence with the proper links, and the thumb is weighted. The vertices in Group 3 that are assigned to the Betty 116 Animating Real-Time Game Characters FIGURE 3.35 The thumb is a little different from the fingers, but you assign the vertices in the same way. Hand link (Link D) can share influence with Betty R FingerO (Link C). Un- hide all the Biped Finger objects of the right hand to test the weighting. Saving Your Weighting Values Most of the time, the best way to save your weighting values is to save it- erative versions of your mesh as you work. You can also easily reuse or recover your weighting by saving the .phy file. Do this by clicking on the Save Physique (*.phy) File icon (Figure 3.36). FIGURE3.36 Save your Physique file for additional insurance or later reference. Chapter 3 Weighting a Character Using Manual Vertex Assignment 117 Keep in mind that when re-loading a physique file into one character or another, the Biped structure has to be the same, with the same added bones (if any) assigned to it. When working with older Biped or 3ds max files, Biped will sometimes revert to the previous version of character studio's naming convention. This means that all Biped links will be named after their child (one link below) instead of the actual bone they correspond to. Assigning the Neck, Shoulders, and Torso Hide m_headarmleg, and unhide m_torso, m_energy, m_fanvent, and all the Biped Spine objects, and go to the Right viewport (Figure 3.37). FIGURE 3.37 Even torso mesh objects are supposed to be heavily armored (that is, rigid). Start with the neck. Since the head is a separate object, it's easier to weight both it and the neck. When the neck is joined to the head, it re- quires more polygons and more time to set up the weighting. Zoom in to the top of the neck, select the vertices there, and assign them to the Betty Head link. Unhide the Biped head and m_headarmleg to test the deformation (Figure 3.38). [...]... for real -time characters, which, by nature, usually need to be animated "in place" for implementation in a game Click on the Load File icon (Figure 3.47) 124 Animating Real -Time Game Characters FIGURE3.47 Click on the yellow Open File icon to load a bip animation into your character Find Run.bip in the Chapter3 directory on this book's CD-ROM, and load it into your character's Biped Click on the Time. .. detached and reattached to the Biped WEIGHTING A CHARACTER USING ENVELOPES 137 138 Animating Real -Time Game Characters C haracters that can be used on many of the consoles today like Nintendo's GameCube™ and Microsoft's Xbox show a substantial increase in the number of polygons available for their models Other real -time applications, such as those with dancing characters for a music visualization plugin,... weighting values right for your real -time character's mesh means the difference between average animations and great animations Without proper weighting, all that hard work spent on the design, model, texture, and rig is wasted Physique allows for quick and easy adjustment of your character's "skin" by giving you access to individual vertices and 134 Animating Real -Time Game Characters FIGURE 3.62 The... The Time Configuration icon brings up the menu that controls the number of frames displayed Once the Time Configuration menu comes up, establish the number of frames in the active animation range by setting the Start Time to 0 and End Time to 18 (Figure 3.49) Changing the length of the animation to match Run.bip allows you to play it in an endless loop if you want Hit OK, and as you slide the Time. .. looks much better 130 Animating Real -Time Game Characters Hide the vertices assigned; select and assign the upper arm element vertices to the Betty L UpperArm link Once they're assigned, hide them as well, and you can then begin work on the real problem area: the belt feed The shoulder for the left arm is a different design from the right one and can move around with the arm The only time it will look... and select all the vertices around her hips Click the Remove from Link button to make it active, go to the Front viewport, and drag your selection fence across all the links on either arm 126 Animating Real -Time Game Characters FIGURE 3.50 These are the options for the In Place Mode icon's fly-out menu Whenever you use Remove from Link, you must select the right type of three available vertices Since... Everything should look good now, except for the three vertices above the ones just corrected Select these three, unlock them, and assign them to the Spine link above the Thigh link (Figure 3.54) 128 Animating Real -Time Game Characters FIGURE 3.54 These three vertices still need a bit of an adjustment to their weighting After you've assigned them to the Spine link, give the vertices a shared value of 0.5 with... that mirror the left foot geometry Assign them to the Betty R Foot link; then, using the left foot vertices as a guide, type in matching values for the right foot vertices (Figure 3.45) 122 Animating Real -Time Game Characters FIGURE 3.44 Selecting the left Foot link to see which vertices are assigned to it also selects some vertices of the right foot geometry FIGURE 3.45 weighted Using the vertices... until you have the values for them shown in Figure 3.61 Note how the forearm is given progressive influence over the feed belt This will result in a smoother deformation of the geometry Now, 132 Animating Real -Time Game Characters FIGURE 3.59 start Being equally influenced by both the Spine2 link and the Forearm link is a FIGURE 3.60 Rotate your view so you can clearly see the row of vertices to be adjusted...118 Animating Real -Time Game Characters FIGURE 3.38 The top of the neck is linked solely to the head to avoid making the gap there visible Since there's no geometry at the top of the neck, the line of vertices there . towards the FIGURE 3.32 Sometimes it's the geometry rather than the weighting that needs to be tweaked to ensure proper deformation. 114 Animating Real -Time Game Characters hand, select. vertices equal influence from both links detracts from the intent of the geometry, which 110 Animating Real -Time Game Characters FIGURE3.27 Beware the confusing out-of-order Forearm link. is to portray. link. FIGURE 3.29 The elbow looks better with the new weighting values. 112 Animating Real -Time Game Characters FIGURE3.30 Biasing the front of the elbow joint to the UpperArm