glm::mat4 VirtualTrackball::rotate(int x, int y) {
//If not rotating, simply return the old rotation matrix
if (!rotating) return quatToMat4(quat_old);
glm::vec3 point_on_sphere_end; //Current point on unit sphere
glm::vec3 axis_of_rotation; //axis of rotation
float theta = 0.0f; //angle of rotation
point_on_sphere_end = getClosestPointOnUnitSphere(x, y);
//Set the axeis of rotation by calculating cross product between the end and begin vectors
axis_of_rotation = glm::cross(point_on_sphere_end, point_on_sphere_begin);
//Set begin point on sphere to normalized start vector
point_on_sphere_begin = glm::normalize(point_on_sphere_begin);
//Set end point on sphere to normalized end vector
point_on_sphere_end = glm::normalize(point_on_sphere_end);
//Calculate the movement angle
theta = glm::degrees(glm::acos(glm::dot(point_on_sphere_begin, point_on_sphere_end)));
//Apply rotation to quaternion
quat_new = glm::rotate(quat_old, theta, axis_of_rotation);
return quatToMat4(quat_new);
}
glm::mat4 VirtualTrackball::rotate(int x, int y) {
//If not rotating, simply return the old rotation matrix
if (!rotating) return quatToMat4(quat_old) /*return glm::mat4_cast(quat_old)*/;
glm::vec3 point_on_sphere_end; //Current point on unit sphere
glm::vec3 axis_of_rotation; //axis of rotation
float theta = 0.0f; //angle of rotation
point_on_sphere_end = getClosestPointOnUnitSphere(x, y);
axis_of_rotation = glm::cross(point_on_sphere_end, point_on_sphere_begin);
theta = glm::degrees(glm::acos(glm::dot(point_on_sphere_begin, point_on_sphere_end)));
quat_new = glm::rotate(quat_old, theta, axis_of_rotation);
/*std::cout << "Angle: " << theta << std::endl;
std::cout << "Axis: " << axis_of_rotation.x << " " << axis_of_rotation.y << " " << axis_of_rotation.z << std::endl;*/
return quatToMat4(quat_new);
}
void VirtualTrackball::rotateBegin(int x, int y) {
rotating = true;
point_on_sphere_begin = getClosestPointOnUnitSphere(x, y);
}