I'm trying to use quaternions in order to rotate objects in my program.
But the problem with them is applying... a rotation.
I'm trying to rotate the matrix in this way:
ModelMatrix = ModelMatrix * glm::toMat4(glm::quat(RotationW, RotationX, RotationY, RotationZ));
quat3 = quat2 * quat1
Model1 = Model * glm::toMat4(glm::quat( quat3.w , quat3.x, quat3.y, quat3.z);
Model2 = Model * glm::toMat4(glm::quat( quat1.w , quat1.x, quat1.y, quat1.z);
Model2 = Model2 * glm::toMat4(glm::quat( quat2.w , quat2.x, quat2.y, quat2.z);
In order for a quaternion to represent a pure rotation, it has to be a unit quaternion. Random numbers usually do not have this property. You may want to normalize them before generating the quaternion:
l = sqrt(RotationW * RotationW + RotationX * RotationX + RotationY * RotationY + RotationZ * RotationZ); RotationW /= l; RotationX /= l; ...
Of course, it does not make any sense to use quaternions only to convert them to a matrix. Directly calculating the matrix will be more efficient.
For the quaternion product, you have it in the wrong order:
q3 = q2 * q1 => M * mat(q3) = M * mat(q2) * mat(q1)