JS-balls-SVG Martin G. Puryear
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JS-balls-SVG
Demonstrates client javascript, including basic collision physics, SVG, and rudimentary audio.
Timer object utilizes browser support for high-resolution timer, if present, otherwise falling back to getTime(). Timer calls the main game loop periodically (default is 1 ms).
Playground object tracks multiple circle objects as they move around the screen. It catches mouse clicks and converts these into Circle objects with certain radius, velocity and 'strength'. Each time the timer fires, the playground object checks for collisions and updates positions. Much of this is done simply by telling each Circle object to do this for itself. However, it also checks for ball-ball collisions, and handles Circle creation/deletion.
Circle object implements a graphics circle that moves around the screen. Note that circles are SVG objects as well as HTML DOM entities. Standard collision detection simply uses Pythagorean calculation to determine distance between objects (for example, comparing this distance to the sum of the two radii for ball-ball collision). The balls bounce off walls as expected, but ball-ball bounce is not implemented.