Android Open Source - android_cubism Cubism Visibility

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License

The source code is released under:

Apache License

Java Source Code

/*
   Copyright 2012 Harri Smatt//www. j  a v a  2s  .  c om

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

package fi.harism.cubism;

import android.util.FloatMath;

public final class CubismVisibility {

  public static void extractPlanes(float[] mvp, float[] result) {
    // Right
    result[0] = mvp[3] - mvp[0];
    result[1] = mvp[7] - mvp[4];
    result[2] = mvp[11] - mvp[8];
    result[3] = mvp[15] - mvp[12];

    // Left
    result[4] = mvp[3] + mvp[0];
    result[5] = mvp[7] + mvp[4];
    result[6] = mvp[11] + mvp[8];
    result[7] = mvp[15] + mvp[12];

    // Bottom
    result[8] = mvp[3] + mvp[1];
    result[9] = mvp[7] + mvp[5];
    result[10] = mvp[11] + mvp[9];
    result[11] = mvp[15] + mvp[13];

    // Top
    result[12] = mvp[3] - mvp[1];
    result[13] = mvp[7] - mvp[5];
    result[14] = mvp[11] - mvp[9];
    result[15] = mvp[15] - mvp[13];

    // Far
    result[16] = mvp[3] - mvp[2];
    result[17] = mvp[7] - mvp[6];
    result[18] = mvp[11] - mvp[10];
    result[19] = mvp[15] - mvp[14];

    // Near
    result[20] = mvp[3] + mvp[2];
    result[21] = mvp[7] + mvp[6];
    result[22] = mvp[11] + mvp[10];
    result[23] = mvp[15] + mvp[14];

    for (int i = 0; i < 24; i += 4) {
      float lenInv = 1f / FloatMath.sqrt(result[i] * result[i]
          + result[i + 1] * result[i + 1] + result[i + 2]
          * result[i + 2] + result[i + 3] * result[i + 3]);
      result[i] *= lenInv;
      result[i + 1] *= lenInv;
      result[i + 2] *= lenInv;
      result[i + 3] *= lenInv;
    }
  }

  public static boolean intersects(float[] planes, float[] sphere) {
    int k = 0;
    for (int i = 0; i < 6; ++i) {
      float dist = planes[k++] * sphere[0] + planes[k++] * sphere[1]
          + planes[k++] * sphere[2] + planes[k++];
      if (dist <= -sphere[3]) {
        return false;
      }
      if (Math.abs(dist) < sphere[3]) {
        return true;
      }
    }
    return true;
  }

}

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