/*****************************************************************************
 *                        J3D.org Copyright (c) 2001
 *                               Java Source
 *
 * This source is licensed under the GNU LGPL v2.1
 * Please read http://www.gnu.org/copyleft/lgpl.html for more information
 *
 ****************************************************************************/

package org.j3d.geom.subdivision;

// Standard imports
// None

// Application specific imports
// None

/**
 * Representation for the eigenvector and weighted coefficients for concave
 * sectors using quads.
 * <p>
 *
 * This class should be overridden by the classes that specialise in generating
 * the coefficients for particular sector types.
 * @author Justin Couch
 * @version $Revision: 1.1 $
 */
class ConcaveQuadRule extends QuadRule
{
    /**
     * Construct a new default instance of this class
     */
    ConcaveQuadRule(int k, float theta)
    {
        super(k, theta, true);

        int i;

        edgeSub[1] = 0.0625f;  // 1/16
        edgeSub[2] = 0.0625f;
        edgeSub[4] = 0.0625f;
        edgeSub[5] = 0.0625f;

        float thetaK = theta / k;

        edgeSub[3] = 0.375f - 0.25f * (float)Math.cos(thetaK);
        edgeSub[0] = 0.75f - edgeSub[3];   // 1 - 2/8 - 3/8 - 1/4 * cos(k)

        // subCoeff - everything else zero
        sub.center = 1;

        // Lambdas
        lambda1 = 0.5f;
        lambda2 = 0.5f;

        // l0 - everything else zero
        l0.center = 1;

        // l1
        l1.center = -1;
        l1.edge[0] = 1;

        // l2
        l2.center = -1;
        l2.edge[k] = 1;

        // x1
        float i_s_t = 1 / (float)Math.sin(theta);

        for(i = 0; i < k+1; i++)
            x1.edge[i] = (float)Math.sin(thetaK * (k-i)) * i_s_t;

        for(i = 0; i < k; i++)
        {
            x1.face[i] = (float)(Math.sin(thetaK * (k - i)) +
                          Math.sin(thetaK * (k - i - 1))) * i_s_t;
        }

        // x2
        System.arraycopy(x1.edge, 0, x2.edge, 0, k);

        for (i = 0; i < k; i++)
            x2.face[i] = (float)(Math.sin(thetaK * i) +
                         Math.sin(thetaK * (i + 1))) * i_s_t;
    }
}