I found unity native drag formula.

nainjoo2001 · August 18, 2022, 10:12am

I got a datas from expriment below
200 1/5
100 2/6
50 3/6
25 4/6
12.5 4/5
10 5/6
5 10/11
1 2.941176

then simply derived to velocity * 50 / (50 + x)
and It applies earlier than FixedUpdate

MelvMay · August 18, 2022, 10:21am

No idea if you’re referring to PhysX or Box2D but why can’t you refer to the source code?

https://documentation.help/NVIDIA-PhysX-SDK-Guide/RigidDynamics.html

erincatto/box2d/blob/9dc24a6fd4f32442c4bcf80791de47a0a7d25afb/src/dynamics/b2_island.cpp#L214


      
          		// Store positions for continuous collision.
          		b->m_sweep.c0 = b->m_sweep.c;
          		b->m_sweep.a0 = b->m_sweep.a;
          
          		if (b->m_type == b2_dynamicBody)
          		{
          			// Integrate velocities.
          			v += h * b->m_invMass * (b->m_gravityScale * b->m_mass * gravity + b->m_force);
          			w += h * b->m_invI * b->m_torque;
          
          			// Apply damping.
          			// ODE: dv/dt + c * v = 0
          			// Solution: v(t) = v0 * exp(-c * t)
          			// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
          			// v2 = exp(-c * dt) * v1
          			// Pade approximation:
          			// v2 = v1 * 1 / (1 + c * dt)
          			v *= 1.0f / (1.0f + h * b->m_linearDamping);
          			w *= 1.0f / (1.0f + h * b->m_angularDamping);
          		}

nainjoo2001 · August 18, 2022, 12:28pm

eh just unity 2021.3 physics value

MelvMay · August 18, 2022, 12:36pm

No idea what that means, sorry.

nainjoo2001 · August 18, 2022, 10:22pm

I mean rigibody.drag value simply

MelvMay · August 19, 2022, 11:20am

Yes, I know what drag is and I replied above giving you links. What else is it you want?

3D Physics is PhysX. The link is above.

Kreshi · August 19, 2022, 12:21pm

I think he just wanted to say that he reverseengineered the formula for drag, but i could be wrong .

nainjoo2001 · August 23, 2022, 5:39am

wait I got some misunderstanding.
the actual formula was velocity /= 1 + drag * Time.fixedDeltaTime