Java Vec2.setZero方法代碼示例

import org.jbox2d.common.Vec2; //導入方法依賴的package包/類
public final void getSearchDirection(final Vec2 out) {
  switch (m_count) {
    case 1:
      out.set(m_v1.w).negateLocal();
      return;
    case 2:
      e12.set(m_v2.w).subLocal(m_v1.w);
      // use out for a temp variable real quick
      out.set(m_v1.w).negateLocal();
      float sgn = Vec2.cross(e12, out);

      if (sgn > 0f) {
        // Origin is left of e12.
        Vec2.crossToOutUnsafe(1f, e12, out);
        return;
      } else {
        // Origin is right of e12.
        Vec2.crossToOutUnsafe(e12, 1f, out);
        return;
      }
    default:
      assert (false);
      out.setZero();
      return;
  }
}
 

import org.jbox2d.common.Vec2; //導入方法依賴的package包/類
/**
 * this returns pooled objects. don't keep or modify them
 * 
 * @return
 */
public void getClosestPoint(final Vec2 out) {
  switch (m_count) {
    case 0:
      assert (false);
      out.setZero();
      return;
    case 1:
      out.set(m_v1.w);
      return;
    case 2:
      case22.set(m_v2.w).mulLocal(m_v2.a);
      case2.set(m_v1.w).mulLocal(m_v1.a).addLocal(case22);
      out.set(case2);
      return;
    case 3:
      out.setZero();
      return;
    default:
      assert (false);
      out.setZero();
      return;
  }
}
 

import org.jbox2d.common.Vec2; //導入方法依賴的package包/類
public final void computeCentroidToOut(final Vec2[] vs, final int count, final Vec2 out) {
  assert (count >= 3);

  out.set(0.0f, 0.0f);
  float area = 0.0f;

  // pRef is the reference point for forming triangles.
  // It's location doesn't change the result (except for rounding error).
  final Vec2 pRef = pool1;
  pRef.setZero();

  final Vec2 e1 = pool2;
  final Vec2 e2 = pool3;

  final float inv3 = 1.0f / 3.0f;

  for (int i = 0; i < count; ++i) {
    // Triangle vertices.
    final Vec2 p1 = pRef;
    final Vec2 p2 = vs[i];
    final Vec2 p3 = i + 1 < count ? vs[i + 1] : vs[0];

    e1.set(p2).subLocal(p1);
    e2.set(p3).subLocal(p1);

    final float D = Vec2.cross(e1, e2);

    final float triangleArea = 0.5f * D;
    area += triangleArea;

    // Area weighted centroid
    e1.set(p1).addLocal(p2).addLocal(p3).mulLocal(triangleArea * inv3);
    out.addLocal(e1);
  }

  // Centroid
  assert (area > Settings.EPSILON);
  out.mulLocal(1.0f / area);
}
 

import org.jbox2d.common.Vec2; //導入方法依賴的package包/類
@Override
  public boolean solvePositionConstraints(final SolverData data) {
    final Rot qA = pool.popRot();
    final Rot qB = pool.popRot();
    final Vec2 rA = pool.popVec2();
    final Vec2 rB = pool.popVec2();
    final Vec2 uA = pool.popVec2();
    final Vec2 uB = pool.popVec2();
    final Vec2 temp = pool.popVec2();
    final Vec2 PA = pool.popVec2();
    final Vec2 PB = pool.popVec2();

    Vec2 cA = data.positions[m_indexA].c;
    float aA = data.positions[m_indexA].a;
    Vec2 cB = data.positions[m_indexB].c;
    float aB = data.positions[m_indexB].a;

    qA.set(aA);
    qB.set(aB);

    Rot.mulToOutUnsafe(qA, temp.set(m_localAnchorA).subLocal(m_localCenterA), rA);
    Rot.mulToOutUnsafe(qB, temp.set(m_localAnchorB).subLocal(m_localCenterB), rB);

    uA.set(cA).addLocal(rA).subLocal(m_groundAnchorA);
    uB.set(cB).addLocal(rB).subLocal(m_groundAnchorB);

    float lengthA = uA.length();
    float lengthB = uB.length();

    if (lengthA > 10.0f * Settings.linearSlop) {
      uA.mulLocal(1.0f / lengthA);
    } else {
      uA.setZero();
    }

    if (lengthB > 10.0f * Settings.linearSlop) {
      uB.mulLocal(1.0f / lengthB);
    } else {
      uB.setZero();
    }

    // Compute effective mass.
    float ruA = Vec2.cross(rA, uA);
    float ruB = Vec2.cross(rB, uB);

    float mA = m_invMassA + m_invIA * ruA * ruA;
    float mB = m_invMassB + m_invIB * ruB * ruB;

    float mass = mA + m_ratio * m_ratio * mB;

    if (mass > 0.0f) {
      mass = 1.0f / mass;
    }

    float C = m_constant - lengthA - m_ratio * lengthB;
    float linearError = MathUtils.abs(C);

    float impulse = -mass * C;

    PA.set(uA).mulLocal(-impulse);
    PB.set(uB).mulLocal(-m_ratio * impulse);

    cA.x += m_invMassA * PA.x;
    cA.y += m_invMassA * PA.y;
    aA += m_invIA * Vec2.cross(rA, PA);
    cB.x += m_invMassB * PB.x;
    cB.y += m_invMassB * PB.y;
    aB += m_invIB * Vec2.cross(rB, PB);

//    data.positions[m_indexA].c.set(cA);
    data.positions[m_indexA].a = aA;
//    data.positions[m_indexB].c.set(cB);
    data.positions[m_indexB].a = aB;

    pool.pushRot(2);
    pool.pushVec2(7);

    return linearError < Settings.linearSlop;
  }