Project 1: Animation System

Assigned: 01/17/06

Due: 01/31/06

Project description

Hierarchical modelingUse OpenGL code to build a model of your

own design Keyframe animation system

Implement three types splines to animate your model

Skeleton code

Modeler View vs. Curves View Graph Widget Interface How to integrate with my model?

just add replace robotarm.cpp with your model build a simple testing model first just to see if

it works

Requirements

Bezier curveSplice Bezier curves together with C0

continuity B-spline Catmull-Rom splines C2-interpolating splines (optional)

Where should I put things?

For each type of splines, create a subclass that inherits from CurveEvaluator Bezier B-spline Catmull-Rom

Implement virtual function evaluateCurve() for each subclass

In GraphWidget class Change the skeleton to call your new constructors in the GraphWidget class.

Extra Credit ideas Tension control for Catmull-Rom

Dn = 1/2(Cn+1 – Cn-1)

Allow control points to have C0, C1, or C2 continuityThis can be VERY helpful in creating a good

animation

Extra Credit ideas “wrapping” the animation

You can implement “wrapping” feature to ensure C0 continuity between the end and the beginning of the animation

Add more control points without changing the curveThis feature is important when you want to

refine your animation in a localize region

Extra Credit ideas Adaptive Bezier curves

Use divide-and-conquer algorithm to display the Bezier curves, rather than sampling at some arbitrary interval

Use GUI to visualize the change of parameters

Implement a C2-interpolating curve There is already an entry in the drop-down menu Allow the user to specify the derivatives of the two

endpoints of your C2-interpolating curve

Extra Credit ideas Procedural modeling

Use procedural algorithm (such as L-systems) to generate all or part of your model

Refine Catmull-Rom splinesUse the two “inner” Bezier control points as

the handles of Catmull-Rom splinesProvide GUI to manipulate the control points

and the handles

Extra Credit ideas Selecting body parts

Implement GUI so that you can click on part of your model to select its animation curve

Speed control Implement “ease-in-ease-out” principle by

manipulating the speed control curve Adding more features to the UI

If there’s anything you don’t like about the UI, change it!

Extra Credit ideas

Talk to me first if you want to implement these featuresQuaternion rotationMotion wapringSubdivision surfaces

Animating well vs. well… just animating

Timing! Timing is VERY, VERY important Consider timing before you bother to

get specific about joint rotations or object positions

Animating well vs. well… just animating

Good timing

Animating well Music!

Sound and music can greatly enhance the cohesion of your artifact

If your artifact idea includes a theme or stylization, it can be very effective to time your animation with events in the theme music.

Good sound

Animating well

Light! Like sound, light is VERY VERY important compositionally Anything you can do to be creative with lighting will help

Light vs. No light

Creating Your Artifact

Choice of curve types I recommend Bezier curves. Why?

Recall the animation of a bouncing ball When the ball hits the ground, the curve describing its

position should have a C1 discontinuity Without C1 discontinuity here, the animation will look wrong

Catmull-Rom is usually the preferred curve choice… but unless your project supports the option to add C1

discontinuity at will, you might find yourself trying to fight the Catmull-Rom to create pauses and other timing goodies

Creating Your Artifact

Compositing Recommended that you break your intended artifact

up into shorter clips combining them all in the end. This will make your life easier for many reasons:

Splitting up work is straightforward Changing camera angles is GOOD for a composition You can incrementally complete your artifact

Download a trial of Adobe Premiere Play around with it, check the website for some details on how to

use it. The user interface is pretty intuitive.

Any Questions?