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# deCastleJau Bezier curves in OpenGL

Somebody please have mercy on me.  I have an assignment that asks the following:

Implement the deCastleJau Algorithm for Bezier curves.  You must use OpenGL function calls for line drawing to approximate the curves.

Your program must draw and display an approximation of the following shapes using cubic Bezier curves and using two different levels of subdivision, rough and smooth.

1. 4 Concentric Circles of radius r,  2r, 3r, 4r.  Pick a reasonable value for r.

2.  An outline of the letter Q.

3.  The fuction y = sin((Pi)x)/(Pi)x
with {x: -2.0, 2.0}
4.  A crude animal or fungus of your choosing.

Like I said in the first statement - somebody please have mercy on me and tell me how to code this in C.
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GeorgeAntoan
1 Solution

Commented:
/* Usual spiel about not doing homework on EE goes here */

I do have some good pseudocode for the cubic case of subdivision for de Castlejau's algorithm:

Polyline subBezier (polyline P)
// Input is polyline P
// n is number of P points (coarse polyline)
// O is output polyline (fine polyline)
j=0;
for ( i=0 ; i<n ; i=+3)
O[j]=P[i];
O[j+1]=(P[i] + P[i+1])/2
O[j+5]=(P[i+2] + P[i+3])/2
t = (P[i+1] + P[i+2])/2
O[j+2]=(t + O[j+1])/2
O[j+4]=(t + O[j+5])/2
O[j+3]=(O[j+2] + O[j+4])/2
j=j+6;
endfor
Return O

This pseudocode is the place to start (or at least where I started when I implemented it).  If you have some more specific questions, I'll answer if I can.
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