DarkflameServer/dCommon/NiQuaternion.cpp

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#include "NiQuaternion.h"
// C++
#include <cmath>
// MARK: Member Functions
Vector3 NiQuaternion::GetEulerAngles() const {
Vector3 angles;
// roll (x-axis rotation)
const float sinr_cosp = 2 * (w * x + y * z);
const float cosr_cosp = 1 - 2 * (x * x + y * y);
angles.x = std::atan2(sinr_cosp, cosr_cosp);
// pitch (y-axis rotation)
const float sinp = 2 * (w * y - z * x);
if (std::abs(sinp) >= 1) {
angles.y = std::copysign(3.14 / 2, sinp); // use 90 degrees if out of range
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} else {
angles.y = std::asin(sinp);
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}
// yaw (z-axis rotation)
const float siny_cosp = 2 * (w * z + x * y);
const float cosy_cosp = 1 - 2 * (y * y + z * z);
angles.z = std::atan2(siny_cosp, cosy_cosp);
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return angles;
}
// MARK: Helper Functions
//! Look from a specific point in space to another point in space (Y-locked)
NiQuaternion NiQuaternion::LookAt(const NiPoint3& sourcePoint, const NiPoint3& destPoint) {
//To make sure we don't orient around the X/Z axis:
NiPoint3 source = sourcePoint;
NiPoint3 dest = destPoint;
source.y = 0.0f;
dest.y = 0.0f;
NiPoint3 forwardVector = NiPoint3(dest - source).Unitize();
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NiPoint3 posZ = NiPoint3Constant::UNIT_Z;
NiPoint3 vecA = posZ.CrossProduct(forwardVector).Unitize();
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float dot = posZ.DotProduct(forwardVector);
float rotAngle = static_cast<float>(acos(dot));
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NiPoint3 vecB = vecA.CrossProduct(posZ);
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if (vecB.DotProduct(forwardVector) < 0) rotAngle = -rotAngle;
return NiQuaternion::CreateFromAxisAngle(vecA, rotAngle);
}
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//! Look from a specific point in space to another point in space
NiQuaternion NiQuaternion::LookAtUnlocked(const NiPoint3& sourcePoint, const NiPoint3& destPoint) {
NiPoint3 forwardVector = NiPoint3(destPoint - sourcePoint).Unitize();
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NiPoint3 posZ = NiPoint3Constant::UNIT_Z;
NiPoint3 vecA = posZ.CrossProduct(forwardVector).Unitize();
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float dot = posZ.DotProduct(forwardVector);
float rotAngle = static_cast<float>(acos(dot));
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NiPoint3 vecB = vecA.CrossProduct(posZ);
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if (vecB.DotProduct(forwardVector) < 0) rotAngle = -rotAngle;
return NiQuaternion::CreateFromAxisAngle(vecA, rotAngle);
}
//! Creates a Quaternion from a specific axis and angle relative to that axis
NiQuaternion NiQuaternion::CreateFromAxisAngle(const Vector3& axis, float angle) {
float halfAngle = angle * 0.5f;
float s = static_cast<float>(sin(halfAngle));
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NiQuaternion q;
q.x = axis.GetX() * s;
q.y = axis.GetY() * s;
q.z = axis.GetZ() * s;
q.w = static_cast<float>(cos(halfAngle));
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return q;
}
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NiQuaternion NiQuaternion::FromEulerAngles(const NiPoint3& eulerAngles) {
// Abbreviations for the various angular functions
float cy = cos(eulerAngles.z * 0.5);
float sy = sin(eulerAngles.z * 0.5);
float cp = cos(eulerAngles.y * 0.5);
float sp = sin(eulerAngles.y * 0.5);
float cr = cos(eulerAngles.x * 0.5);
float sr = sin(eulerAngles.x * 0.5);
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NiQuaternion q;
q.w = cr * cp * cy + sr * sp * sy;
q.x = sr * cp * cy - cr * sp * sy;
q.y = cr * sp * cy + sr * cp * sy;
q.z = cr * cp * sy - sr * sp * cy;
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return q;
}