# Cubic Bezier Curves

• Dec 6th 2008, 10:38 AM
crodragn
Cubic Bezier Curves
I'm trying to implement a program to draw some bi-cubic bezier curves, however there seem to be some gaps in my notes on how exactly one caculates the (x,y) coords for points on regular cublic bezier curves (a necessary subset). Pulled from my notes:
Code:

```P(u)=[u3,u2,u,1] [-1,  3, -3, 1] [P0]                 | 3, -6,  3, 0| |P1|                 |-3,  3,  0, 0| |P2|                 [ 1,  0,  0, 0] [P3]```
(I apologize for formating abuse, that is supposed to be 3 matrix's)

I have (x,y,z,w) for each of the 4 control points, though only x and y are variable (z=0, w=1, neither probably applies to this problem). The center matrix I know is the Bezier matrix, which is constant. I'm trying to get 10 steps out of this, so I think this means U increments by .1 on each of 10 steps. Problem is, I have no idea what the P values are nor the outputs of the function are.
• Dec 6th 2008, 07:55 PM
crodragn
Question resolved. P is X or Y of each control point, output is X or Y value, calculated independently.