float Physics::angleBetween(const Vector& from, const Vector& to) {
// float angle = acos(from.dotProduct(to) / (float) (from.getLength() * to.getLength()));
float angle = safeAcos(from.dotProduct(to) / (float) (from.getLength() * to.getLength()));
if(to.y < from.y) {
angle = 2 * M_PI - angle;
}
return angle;
}
float Quaternion::getRotationAngle() const {
// Compute the half angle. w = cos(theta / 2)
float thetahalf = safeAcos(w);
// Return the rotation angle
return thetahalf * 2.0f;
}
float Quaternion::getRotationAngle() const
{
// Compute the half angle. Remember that w = cos(theta / 2)
float thetaOver2 = safeAcos(w);
// Return the rotation angle
return thetaOver2 * 2.0f;
}
float Physics::angleTo(const Vector& fromPoint, const Vector& toPoint) {
// This method is a bottleneck, so using Vector is avoided.
float diffX = toPoint.x - fromPoint.x;
float diffY = toPoint.y - fromPoint.y;
float length = sqrt(diffX*diffX + diffY*diffY);
float angle = safeAcos(diffX / length);
// float angle = acos(diffX / length);
if(diffY < 0) {
angle = 2 * M_PI - angle;
}
return angle;
}
bool isConvex(const float3 pt[], std::size_t n)
{
float angleSum = 0.0f;
for (std::size_t i = 0; i < n; i++)
{
Vector3t<float> e1;
if (i == 0)
{
e1 = pt[n - 1] - pt[i];
}
else
{
e1 = pt[i - 1] - pt[i];
}
Vector3t<float> e2;
if (i == n - 1)
{
e2 = pt[0] - pt[i];
}
else
{
e2 = pt[i + 1] - pt[i];
}
e1 = normalize(e1);
e2 = normalize(e2);
float d = dot(e1, e2);
float theta = safeAcos(d);
angleSum += theta;
}
float convexAngleSum = (float)(n - 2) * M_PI;
if (angleSum < convexAngleSum - (float)n * 0.0001f)
{
return false;
}
return true;
}
float Quaternion::getRotationAngle() const
{
float alpha = safeAcos(w);
return alpha*2.0f;
}
// 提取旋转角和旋转轴
float Quaternion::getRotateAngle()const
{
float thetaOver2 = safeAcos(w);
return 2.0f*thetaOver2;
}
