Simulation and Drawing process


Let's start with definitions

Computer animation refers to any time sequence of visual changes in a picture. In addition to changing object positions using translations or rotations, a computer-generated animation could display time variations in object size, color, transparency, or surface texture.

There are 2 types on methods to construct motion sequences:

  • Real-time animation, where each stage of the sequence is viewed as it is created. It must be generated at a rate that is compatible with the constraints of the refresh rate.

  • frame-by-frame animation, ach frame of the motion is separately generated and stored. Later, the frames can be recorded on film, or they can be displayed consecutively on a video monitor in “real-time playback” mode.

Design of animation sequences (stages)

  1. The storyboard is an outline of the action. It defines the motion sequence as a set of basic events that are to take place.

  2. An object definition is given for each participant in the action. Objects can be defined in terms of basic shapes, such as polygons or spline surfaces.

  3. A key frame is a detailed drawing of the scene at a certain time in the animation sequence. Within each key frame, each object (or character) is positioned according to the time for that frame.

  1. In-betweens are the intermediate frames between the key frames. The total number of frames, and hence the total number of in-betweens, needed for an animation is determined by the display media that is to be used.

Animation techniques

Film animators use a variety of methods for depicting and emphasizing motion sequences. These include object deformations, spacing between animation frames, motion anticipation and follow-through, and action focusing. Some traditional techniques are:

  • squash and stretch
  • timing
  • anticipation
  • Follow-through actions
  • Staging

Animation techniques (squash and stretch)

Challenge: Bouncing-ball (processing)

We will implement an animation that will simulate a ball that is bouncing as shown in figure 4

Your program will be showing 3 stages or scenes that will be transitioned by a mouse right-click

Consider the concepts you saw in class and also the following that could be useful:

gravity, refresh-rate, object deformation, timing, real-time animation, curves drawing algorithms, color, texture, ...

Below the 3 main stages or scenes of your program

  • Click 1 - Define and draw your ball's trajectory and draw it. You can use 2 curves, one that is going down and one that is going up.

  • Click 2 - Draw a summary of your storyboard based on figures 4 and 5. Only draw some selected frames that will provide a glimpse of your animation.

  • Click 3 - Run your ball-bouncing simulation. Your ball will follow the pre-defined curved trajectories. Your ball will be deformed as it's going down/up.

What's next

- Collisions

Resources and Credits

This material is genereated thanks to some extracts from following resources:

  • Computer Graphics with OpenGL (Chapters 11) by Donald D. Hearn/M. Pauline Baker, Warren Carithers, 4th Edition


  • Obed N Muñoz Reynoso
    • Cloud Software Engineer
    • obed.n.munoz@gmail | tec |