Learning Objectives

The focus in this session is on

  • getting a better grip on how to move sub-parts and
  • using object and camera markers.

The Tiger in the Desert

Demo Project Tiger

This video shows you a simple example on how you can use these features.

Object and Camera Markers

Tiger with Object Marker

Alice allows to set Object and Camera Markers. Both type of markers allow you to fix positions on the scene that you can use to move objects to. Details on how to use Camera Markers and Camera and Object Markers you find in these two videos.

Walking

The three code snippets below can be used to make a biped walk. In order to be able to use the methods not only for the tiger, but for all bipeds, we are defining two procedures in class Biped. One way to create those proecedures is by opening the object tree browser, selecting the Biped class and then clicking on New Procedure. The whole process is described in an older tutorial here, the method walk in that post is slightly different, the method described below here is simpler.

You will need to create two procedures, firstStep and walk.

firstStep brings the biped from the standing position to a walking position.

procedure_firstStep

walk consists on two halfsteps, so the biped finishes in the same position it started.

procedure_walk

In order for the biped to stand properly after walking, we use the built-in procedure straigtenOutJoints.

These three methods and some more to show the use of camera and object markers are used inside the procedure myFirstMethod. myFirstMethode_Code. The video at the beginning of this post is the full animation.

The walking algorithm used here is very basic, but this is on purpose as it makes coding faster. The code snippet below places the walk method inside a count loop, so the tiger takes 1 + 6 half steps, forth and back.

Walking only

There are more realistic procedures for walking available here, you may have a look ahead of next session if you like.

Furthermore, there is a very comprehensive tutorial on sub-parts/joint movements on the Alice 3 website, here is the link to the page.