I am shifting from directX to Opengl and wondered why the

fourth row of the view matrix of opengl is negated?

by fourth row i meant the look vector since in opengl it is arranged in column major order.

my confusion is that when i checked some of opengl tutorials, some of them DOES NOT negate the look vector.

but i checked the LookAt function of GLM, it did negate the look/target vector.

the value is different from that of DirectX, where only the eye position is negated to subtract the camera position to the vertices of the objects.

Is this because in OpenGL the coordinates is facing -Z instread of +Z?