When we talk about torque, we are generally talking about the tendency of a force or impulse to rotate an instance about its centre of mass, but in GameMaker Studio 2 you can also apply torque independently to an instance, causing it to rotate in a given direction. How much torque you apply to get the desired rotation all depends on the size and density of the fixture you assign to your instance, as both these properties go towards defining its mass, which defines its inertia, which affects torque! The general rule of thumb is that if an instance has a lot of inertia, you will need a lot of torque to get it to start rotating. It should also be noted that other factors like gravity and collisions can also affect the torque of an instance. Here is an image to help explain:
As you can see, the amount of torque you need to rotate the object depends on the underlying mass and inertia that it gives. This is all calculated for you by GameMaker Studio 2 based on the size and density of the fixture that is assigned to the instance when it is created. Also note that for anti-clockwise rotation, the value should be negative.
|torque||The torque (in Newton metres) to be applied|
if keyboard_check(vk_left) physics_apply_torque(-100);
The code above will rotate the instance to the anti-clockwise (to the left) with a torque of 100Nm when the left arrow key is pressed.