scummvm/math/matrix3.cpp
Einar Johan Trøan Sømåen fcb8eda978 MATH: Add some constexpr to the Matrix base-classes.
Currently we can't quite make Matrix3's default constructor constexpr,
as the setToIdentity-call requires C++14.
2023-04-29 13:10:23 +02:00

65 lines
2.3 KiB
C++

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#include "math/matrix3.h"
namespace Math {
void swap (float &a, float &b) {
float c = a; a = b; b = c;
}
void Matrix<3, 3>::transpose() {
swap(operator()(0, 1), operator()(1, 0));
swap(operator()(0, 2), operator()(2, 0));
swap(operator()(1, 2), operator()(2, 1));
}
/**
* Generates a lookat matrix. For reference, see
* http://clb.confined.space/MathGeoLib/nightly/docs/float3x3_LookAt.php
*/
void Matrix<3, 3>::buildFromTargetDir(const Math::Vector3d &modelForward, const Math::Vector3d &targetDirection,
const Math::Vector3d &modelUp, const Math::Vector3d &worldUp) {
Math::Vector3d modelRight = Math::Vector3d::crossProduct(modelUp, modelForward);
modelRight.normalize();
Math::Vector3d worldRight = Math::Vector3d::crossProduct(worldUp, targetDirection);
worldRight.normalize();
Math::Vector3d perpWorldUp = Math::Vector3d::crossProduct(targetDirection, worldRight);
perpWorldUp.normalize();
Math::Matrix3 m1;
m1.getRow(0) << worldRight.x() << worldRight.y() << worldRight.z();
m1.getRow(1) << perpWorldUp.x() << perpWorldUp.y() << perpWorldUp.z();
m1.getRow(2) << targetDirection.x() << targetDirection.y() << targetDirection.z();
m1.transpose();
Math::Matrix3 m2;
m2.getRow(0) << modelRight.x() << modelRight.y() << modelRight.z();
m2.getRow(1) << modelUp.x() << modelUp.y() << modelUp.z();
m2.getRow(2) << modelForward.x() << modelForward.y() << modelForward.z();
this->operator=(m1 * m2);
}
} // end of namespace Math