Quaddratic Bezier Curve: Calculate Tangent
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Published on 2010-04-02T22:48:23Z
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Hello,
I have have a quadratic bezier curve and I want to calculate the slope of the tangent in a given point. For example, let it be the middlepoint of the quadratic bezier curve, therefore t=0.5 (please see the link below for a picture of this). I've calculated the first derivation of the formula for the quadratic bezier curve, however I get 400 as value for the slope, though it should be 0. Maybe I'm using the first derivation in a wrong way? I know I could also calculate the tangents using trigonometric functions, however I'd like to do it using the first derivation, shouldn't this be possible? Thanks for any hint!
For clarification / please note: I'm interested in a general way to get the slope in a arbitrary given point on a quadratic bezier curve, not only to get the tangent in the start- and end point.
A picture of my problem including the text above: http://cid-0432ee4cfe9c26a0.skydrive.live.com/self.aspx/%c3%96ffentlich/Quadratic%20Bezier%20Curve.pdf
Thank you very much for any hint!
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