Hi Michael,
Bug 4718786 - Incorrect coefficients in CubicSplineSegment
computeCommonCoefficients()
is submitted for investigation.
Thanks for your bug report.
- Kelvin
------------------
Java 3D Team
Sun Microsystems Inc.
>Date: Sat, 20 Jul 2002 15:43:44 +0200
>From: Michael Nischt <[EMAIL PROTECTED]>
>Subject: [JAVA3D] TCB-Splines and CubicSplineSegments
>To: [EMAIL PROTECTED]
>MIME-version: 1.0
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>
>Hi all,
>
>I've taken a look at the source in the
>com.sun.j3d.utils.behaviors.interpolators package and
>I wonder about two things:
>
>1.
>in RotPosScaleTCBSplinePathInterpolator.java
>
> private Matrix4d sMat = new Matrix4d(); // line 64:
>
>but sMat is never used.
>
>2.
>in CubicSplineSegment.java
>
> // variables for destination derivative
> float one_minus_t_in;
> float one_minus_c_in;
> float one_minus_b_in;
> float one_plus_c_in;
> float one_plus_b_in;
>
> // variables for source derivative
> float one_minus_t_out;
> float one_minus_c_out;
> float one_minus_b_out;
> float one_plus_c_out;
> float one_plus_b_out;
>
> ....
>
> // compute the common coefficients
> private void computeCommonCoefficients (TCBKeyFrame kf0,
> TCBKeyFrame kf1,
> TCBKeyFrame kf2,
> TCBKeyFrame kf3) {
>
> // variables for destination derivative
> float one_minus_t_in = 1.0f - kf1.tension;
> float one_minus_c_in = 1.0f - kf1.continuity;
> float one_minus_b_in = 1.0f - kf1.bias;
> float one_plus_c_in = 1.0f + kf1.continuity;
> float one_plus_b_in = 1.0f + kf1.bias;
>
> // coefficients for the incoming Tangent
> ddb = one_minus_t_in * one_minus_c_in * one_minus_b_in;
> dda = one_minus_t_in * one_plus_c_in * one_plus_b_in;
>
> // variables for source derivative
> float one_minus_t_out = 1.0f - kf2.tension;
> float one_minus_c_out = 1.0f - kf2.continuity;
> float one_minus_b_out = 1.0f - kf2.bias;
> float one_plus_c_out = 1.0f + kf2.continuity;
> float one_plus_b_out = 1.0f + kf2.bias;
>
> // coefficients for the outgoing Tangent
> dsb = one_minus_t_in * one_plus_c_in * one_minus_b_in;
> dsa = one_minus_t_in * one_minus_c_in * one_plus_b_in;
> }
>
>
>the one_xxx_y_zz attributes are never used, because of the local definitions.
>and wouldn't it be correct:
>
> // coefficients for the outgoing Tangent
> dsb = one_minus_t_out * one_plus_c_out * one_minus_b_out;
> dsa = one_minus_t_out * one_minus_c_out * one_plus_b_out;
>
>instead of
>
> // coefficients for the outgoing Tangent
> dsb = one_minus_t_in * one_plus_c_in * one_minus_b_in;
> dsa = one_minus_t_in * one_minus_c_in * one_plus_b_in;
>
>
>
>the first looks to me as copyright protection-inserts, but the last one makes
>no sense to me..
>
>regards
>-Michael Nischt
>
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