// jump duration == 2*sv_jumpvelocity / sv_gravity
// in this case: 0.6888888888 (thus either 20 or 21 frames)
// jump height == sv_jumpvelocity^2 / (2*sv_gravity)
// jump duration == 2*sv_jumpvelocity / sv_gravity
// in this case: 0.6888888888 (thus either 20 or 21 frames)
// jump height == sv_jumpvelocity^2 / (2*sv_gravity)