Android Open Source - Cardboard Head Transform

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Back to project page Cardboard.
License

The source code is released under:
Apache License
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Java Source Code

package com.google.vrtoolkit.cardboard;
/*from w w w .  jav  a 2 s  .  com*/
import android.opengl.Matrix;
import android.util.FloatMath;

public class HeadTransform {
  private static final float GIMBAL_LOCK_EPSILON = 0.01F;
  private static final float PI = 3.1415927F;
  private final float[] mHeadView;

  public HeadTransform() {
    this.mHeadView = new float[16];
    Matrix.setIdentityM(this.mHeadView, 0);
  }

  float[] getHeadView() {
    return this.mHeadView;
  }

  public void getHeadView(float[] headView, int offset) {
    if (offset + 16 > headView.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    System.arraycopy(this.mHeadView, 0, headView, offset, 16);
  }

  public void getTranslation(float[] translation, int offset) {
    if (offset + 3 > translation.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    for (int i = 0; i < 3; i++) {
      translation[(i + offset)] = this.mHeadView[(12 + i)];
    }
  }

  public void getForwardVector(float[] forward, int offset) {
    if (offset + 3 > forward.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    for (int i = 0; i < 3; i++) {
      forward[(i + offset)] = (-this.mHeadView[(8 + i)]);
    }
  }

  public void getUpVector(float[] up, int offset) {
    if (offset + 3 > up.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    for (int i = 0; i < 3; i++) {
      up[(i + offset)] = this.mHeadView[(4 + i)];
    }
  }

  public void getRightVector(float[] right, int offset) {
    if (offset + 3 > right.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    for (int i = 0; i < 3; i++) {
      right[(i + offset)] = this.mHeadView[i];
    }
  }

  public void getQuaternion(float[] quaternion, int offset) {
    if (offset + 4 > quaternion.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    float[] m = this.mHeadView;
    float t = m[0] + m[5] + m[10];
    float x;
    float y;
    float z;
    float w;
    float s;
    if (t >= 0.0F) {
      s = FloatMath.sqrt(t + 1.0F);
      w = 0.5F * s;
      s = 0.5F / s;
      x = (m[9] - m[6]) * s;
      y = (m[2] - m[8]) * s;
      z = (m[4] - m[1]) * s;
    } else {
      if ((m[0] > m[5]) && (m[0] > m[10])) {
        s = FloatMath.sqrt(1.0F + m[0] - m[5] - m[10]);
        x = s * 0.5F;
        s = 0.5F / s;
        y = (m[4] + m[1]) * s;
        z = (m[2] + m[8]) * s;
        w = (m[9] - m[6]) * s;
      } else {
        if (m[5] > m[10]) {
          s = FloatMath.sqrt(1.0F + m[5] - m[0] - m[10]);
          y = s * 0.5F;
          s = 0.5F / s;
          x = (m[4] + m[1]) * s;
          z = (m[9] + m[6]) * s;
          w = (m[2] - m[8]) * s;
        } else {
          s = FloatMath.sqrt(1.0F + m[10] - m[0] - m[5]);
          z = s * 0.5F;
          s = 0.5F / s;
          x = (m[2] + m[8]) * s;
          y = (m[9] + m[6]) * s;
          w = (m[4] - m[1]) * s;
        }
      }
    }
    quaternion[(offset + 0)] = x;
    quaternion[(offset + 1)] = y;
    quaternion[(offset + 2)] = z;
    quaternion[(offset + 3)] = w;
  }

  public void getEulerAngles(float[] eulerAngles, int offset) {
    if (offset + 3 > eulerAngles.length) {
      throw new IllegalArgumentException(
          "Not enough space to write the result");
    }
    float pitch = (float) Math.asin(this.mHeadView[6]);
    float roll;
    float yaw;
    if (FloatMath.sqrt(1.0F - this.mHeadView[6] * this.mHeadView[6]) >= 0.01F) {
      yaw = (float) Math.atan2(-this.mHeadView[2],
          this.mHeadView[10]);
      roll = (float) Math.atan2(-this.mHeadView[4], this.mHeadView[5]);
    } else {
      yaw = 0.0F;
      roll = (float) Math.atan2(this.mHeadView[1], this.mHeadView[0]);
    }
    eulerAngles[(offset + 0)] = (-pitch);
    eulerAngles[(offset + 1)] = (-yaw);
    eulerAngles[(offset + 2)] = (-roll);
  }
}
Java Source Code List
