A walk cycle is a series of illustrations drawn in sequence that loop to create an animation of a walking character.
This tutorial covers the basics on how to construct a 4-frame walk cycle using Flash. A walk cycle can be broken into four key poses. These key poses are the defining points of a walk cycle:
- Forward Contact Point
- Back Contact Point
- Passing Pose 1
- Passing Pose 2
Since the leg of the character changes shape, we’ll employ guides to help maintain the volume of the leg. To help us maintain a steady size ratio, we need a reference point. Just to make sure we’re all on the same page, listed below are the publishing settings I used.
Dimensions: 585×400 pixels (width x height); Frame Rate: 6 FPS.
To start off, the first thing we’re going to do is get the leg animation nailed down correctly so that the four key frames look something like this:
The leg is defined by the highest point (pelvis) and the lowest point (indicated by the guide line).
There are many ways of going about animating a walk cycle. This method is one of the better methods I use since it’s easy and has the quickest turnaround time. I’ve broken up this tutorial into three steps:
- Step A: Understanding walk cycle and animating the two legs
- Step B: Rigging the character
- Step C: Animating the character
When I create a walk cycle, I make it a point to have the registration point at the lowest center of gravity (CG). Therefore, I set the registration point to coincide with the pivot point of the character. This isn’t a rule, but from all my experience as an animator I know this works best because you never know when you’ll need to skew or rotate the symbol.
Our first step is to create a graphic symbol which has its registration point set at the lowest CG of the character. Then we’ll go ahead and animate one of the legs using a copy-paste method, and animate the second leg too.
Step A: Animating the Legs
- Draw a line on the work area
- Select the line and convert it to a graphic symbol. Make sure to change the registration to the the lower-center-bottom spot (as indicated in the image below).
The registration point acts as the pivot to that symbol. For easy animation, we reposition the registration points so that we can pivot or skew that symbol in our favor when animating the character.
- Enter the symbol, delete the line and drag a guide line to that registration point. The guide now serves as reference for the ground.
- Create two layers, namely “pelvis” and “leg” and stretch the timeline from one frame to four frames so it looks something like below.
- Draw the pelvis on the first frame of the “pelvis” layer. Drag two guide lines to the top and center of the pelvis. Lock the pelvis layer and convert all frames on the “leg” layer to blank keyframes.
- With the pelvis and guide line as reference, draw the Forward Contact Point on Frame 1 in the “leg” layer. Switch on the Onion Skin feature to help you draw the rest of the frames.
- Draw the Back Contact Point on Frame 3
- Draw the Passing Pose 1 on Frame 2
- Draw the Passing Pose 2 on Frame 2
Download the 4-frame walk cycle for one leg (For Flash 8 and above).
Now that we have one leg of the walk cycle nailed down properly, the other leg is more or less a copy-paste job.
- Create a new layer between “leg” and “pelvis.” Rename the layer “leg2″
- Convert all frames on “leg2″ to blank keyframes. Looking at the “Breakdown of Walk Cycle” image at the beginning of the tutorial we can observe a pattern the legs follow. When the first leg (black) is at the Forward Contact Point, the second leg (blue) is at the Backward Contact Point; or when the first leg (black) is at the Passing Point 1, the second leg (blue) is at passing point 2. Thus, it can be said that the second leg (blue) is two frames ahead of the first leg (black).
- Armed with the above knowledge, we can copy:
Frame 1 of “leg” ——paste to——> Frame 3 of “leg2″
Frame 2 of “leg” ——paste to——> Frame 4 of “leg2″
Frame 3 of “leg” ——paste to——> Frame 1 of “leg2″
Frame 4 of “leg” ——paste to——> Frame 2 of “leg2″
Here’s a video demonstration of how the above steps can be done using an alternative quicker method.
[flv:http://www.devilsgarage.com/wp-content/uploads/2010/05/how-to-copy-frames.flv 585 503]
Download the 4-frame walk cycle for both legs (For Flash 8 and above).
Now that we have our foundation walk cycle, the next set of steps is rigging the graphic symbols so that we can start animating the remaining body parts.
Disclaimer: this tutorial was made using Adobe Flash CS3.