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From: Lewis_Evans@Playstation.sony.com
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: Rainbow snake effect?
Date: 17 Feb 1998 06:00:56 -0000
Organization: Sony Computer Entertainment Europe - 119.SS5
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From: Lewis_Evans@Playstation.sony.com
To: news@playstation.co.uk

I want to produce the effect of a texture-mapped snake/ribbon with a
definate width.  Does anyone have any suggestions as to how I could do
this?  Representing it as a bunch of lines is, I guess, possible, but
probably won't draw fast enough: I don't really want to use the 3D
engine for polygons, and if I do, I'm not sure how I'd do it because
the details of the model would be changing on the fly as it moved
around the screen (and curled, bent, etc).  Any tips?


One way is to build the snake from sections; each section could be a
quadrilateral.
All you need is a simple clear way of describing the shape of the snake
itself,
eg a spline or a list of rotations from one section to the next;
from this description, you can generate the snake from polygons.
Changing the model on the fly just requires that you double buffer the
model,
ie just have two models and a buffer index and alter the model that's not
being
rendered; for examples of manipulation of polygons/TMDs, see the SCEE demos
clone, chrome and Between The Eyes. It's quite straightforward to alter the
vertices
of polys to make them fit smoothly around the backbone line of your snake.

     Lewis