a port of the Processing Visualization Language
Name

curveTangent()

Examples
example pic
noFill();
curve(5, 26, 73, 24, 73, 61, 15, 65); 
int steps = 6;
for (int i = 0; i <= steps; i++) {
  float t = i / float(steps);
  float x = curvePoint(5, 73, 73, 15, t);
  float y = curvePoint(26, 24, 61, 65, t);
  //ellipse(x, y, 5, 5);
  float tx = curveTangent(5, 73, 73, 15, t);
  float ty = curveTangent(26, 24, 61, 65, t);
  float a = atan2(ty, tx);
  a -= PI/2.0;
  line(x, y, cos(a)*8 + x, sin(a)*8 + y);
}
Description Calculates the tangent of a point on a curve. There is a good definition of "tangent" at Wikipedia: http://en.wikipedia.org/wiki/Tangent
Syntax
curveTangent(a,b,c,d,t)
Parameters
a int or float: coordinate of first point on the curve
b int or float: coordinate of first control point
c int or float: coordinate of second control point
d int or float: coordinate of second point on the curve
t float: value between 0 and 1
Usage Web & Application
Related curve()
curveVertex()
curvePoint()
bezierTangent()

This reference is licensed under the CC BY-NC-SA 2.0 license:

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