Setting Up the Initial Scene

Problem Solving in Alice Set up the initial scene in a new world The princess example Setting up the initial scene

Select Template

Add Objects Click on Add Objects button Toggles from code editor to scene editor

Scene Editor Add objects to the world Two options Drag and drop Click on thumbnail; then click on Add Instance button Add dragon from Web gallery’s Medieval collection

Position & Orientation Objects are positioned in 3-D space have a sense of orientation have six degrees of freedom (directions of movement)

Mouse Control Toolkit To reposition objects in the world, use the buttons in the mouse control toolkit

Starting the initial scene Open the PrincessAndDragon world (Hdrive) Do Save World As and save the file on your p-drive or on a flash drive Add the dragon and position it in the scene Add the princess and position her in the scene  hint how to do that further

Pull-down menu methods Alternative technique for positioning object and subparts during scene setup.

Quad View – Relative Positioning

Empty quad view pane? Scroll & Zoom controls can be used (usually) to reorient the camera view.

Save the world This is a world that we will use in a few lessons.

Motion Motion of an object is relative to the orientation of the object the center of the object

Orientation Orientation is an object’s sense of direction A 3D object has 3 dimensions height, width, depth 6 directions of motion

Center of an object An object is positioned in the world, with reference to the center of the object. The center of an object can be: At the center of mass, or Where it stands on the ground, or Where it is held or connected (for example, a hinge joint)

Bounding Box Viewing the intersection of axes in an object’s bounding box is one way to determine where the center of an object is located.

Demo & Practice Create a new world tortoise (Animals gallery) evilNinja (People gallery) Where is the center of each object? What is the forward direction of each? What is the up direction of each?

Translational Motion Change of position of a whole object in the world The direction of translational motion is stated relative to the orientation of the object. Six possible directions move left right up down forward backward

Set-up methods To illustrate object motion, we will use the scene editor’s popup menu of set-up methods. Demo of using a set-up method: Add a 3D axes object to the world with the tortoise and evilNinja Right-click on the 3D axes object Select “methods” from the menu Select a method

Selecting set-up method: orient to

Demo & Practice Use a set-up move instruction with tortoise evilNinja Note: You can click the Undo button to return an object to its initial position before trying another move.

Question Other than move, what other methods in the set-up popup menu can be used for “translational motion”?

Rotational Motion: Entire Object Rotational motion changes the orientation of an object in the world An object’s center acts as its pivot point for rotation of the whole object. Two forms of rotational motion: turn forward, backward left, right Roll left, right Rotational Motion: Entire Object

Two forms of rotational motion: turn forward, backward: rotation about the “right”- axis left, right: rotation about the “up”-axis Roll: rotation about the “forward”-axis left, right Rotational Motion: Entire Object

Hands-On Practice Add a biplane (Vehicles gallery) to the world Use turn and roll set-up methods with the whole biplane Note: Be sure to click the Undo button to return to initial position before trying another rotational motion. Note how the movement is around the biplane’s center (which is within the body of the biplane)

Question Other than turn and roll, what other methods in the set-up method menu can cause “rotational motion”?

Rotational Motion: Subpart Rotational motion of a subpart of an object may have a surprising result Turn and roll actions for a subpart are pivoted around the center of the subpart, generally located where the subpart connects to the rest of the object (see example, next slide)

Example The tortoise’s right arm is centered at the base (the connecting joint) of the upper arm to the body Note: A few Alice 2 models were designed to work differently and, therefore, do not conform to this standard structure.

Center for a subpart One way to view the center of a subpart and its orientation is to set the point of view of an axes object to the subpart. Example: tortoise rightArm’s center