CODEWITHSUNDEEP
c++openglglm-math
Aulaulz
Aulaulz

Reputation: 469

c++ quaternion clarification

I'm working on a flight simulator. I've read a tutorial about quaternions, ( this one : http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-17-quaternions/ ), so It it very new for me.

From what I've understand, quaternions should rotate an object using a direction vector and make the object's orientation match the direction, and rotate the quaternion should not move the vector, but just make him turn around himself. Am I true?

If yes, this is my code :

void Plane::Update()
{
    m_matrix = GLM_GTX_quaternion::toMat4( GLM_GTX_quaternion::angleAxis( radians( m_angle ), normalize( m_planeDirection ) ) );
}

When my plane model's is pointing to x vector, my plane will rotate correctly around the x vector with the angle equal to 0, but if I change the angle, it will not rotate correctly. So how can I find the angle?

Upvotes: 0

Views: 177

Answers (1)

Iggy
Iggy

Reputation: 4888

Yes, you are correct - Quaternion rotates an object around a directional vector. You should also use the glm::quat typedef when working with quaternions.

#include <glm/gtc/quaternion.hpp>
//...
glm::mat4 m = glm::mat4_cast(glm::angleAxis(glm::radians(m_angle), glm::normalize(m_planeDirection)));

glm::rotate function also works with quaternions

glm::mat4 m = glm::mat4_cast(glm::rotate(glm::quat(), 45.0f, glm::vec3(1.0f)));

Upvotes: 1

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