public void setFov(float fovY) {
        if (fovY <= 0) {
            throw new IllegalArgumentException("Field of view must be greater than 0");
        }
        if (this.parallelProjection) {
            throw new IllegalArgumentException("Cannot set field of view on orthogonal camera");
        }
        float h = FastMath.tan(fovY * FastMath.DEG_TO_RAD * .5f) * frustumNear;
        float w = h * getAspect();
        frustumLeft = -w;
        frustumRight = w;
        frustumBottom = -h;
        frustumTop = h;
        onFrustumChange();
    }
Sets the field of view when the camera is in perspective mode. Note that this method has no
effect when the camera is in orthogonal mode.

@param fovY   Frame of view angle along the Y in degrees. This must be greater than 0.
jme3-core/src/main/java/com/jme3/renderer/Camera.java