How to add buoyancy in Newton 3?

[Leadwerks]

I am implementing water in our engine and I have no idea how to add this in Newton 3. I have some old code for it, but there are parts commented out, and the applied force is zero.

It looks like the command NewtonConvexCollisionCalculateBuoyancyAcceleration() was present in Newton.cpp at one time, but was removed?:

newton-dynamics/newton-3.14/sdk/dgNewton/Newton.cpp

Line 3047 in a059c83

//void NewtonConvexCollisionCalculateBuoyancyAcceleration (const NewtonCollision* const convexCollision, const dFloat* const matrix, const dFloat* const shapeOrigin, const dFloat* const gravityVector, const dFloat* const fluidPlane, dFloat fluidDensity, dFloat* const accel, dFloat* const alpha)

How can I add buoyancy to an object?

void PhysicsNode::AddBuoyancyForce(const dFloat nx, const dFloat ny, const dFloat nz, const dFloat d, const dFloat fluidDensity, const dFloat fluidViscosity)
{
	dFloat Ixx;
	dFloat Iyy;
	dFloat Izz;
	dFloat mass;
	const float m_waterToSolidVolumeRatio = 0.5;
	dVector m_plane = dVector(nx, ny, nz, d);
	NewtonBodyGetMass(newtonbody, &mass, &Ixx, &Iyy, &Izz);
	if (mass > 0.0f)
	{
		dMatrix matrix;
		dVector cog(0.0f);
		dVector accelPerUnitMass(0.0f);
		dVector torquePerUnitMass(0.0f);
		const dVector gravity(0.0f, world->gravity.y, 0.0f, 0.0f);

		NewtonBodyGetMatrix(newtonbody, &matrix[0][0]);
		NewtonBodyGetCentreOfMass(newtonbody, &cog[0]);

		Mat4 mat = Mat4((float*)&matrix[0][0]);
		Mat4 identity;
		Vec3 v = TransformPoint(cog[0], cog[1], cog[2], mat, identity);
		cog[0] = v.x; cog[1] = v.y; cog[2] = v.z;
		//cog = matrix.TransformVector(cog);

		NewtonCollision* const collision = NewtonBodyGetCollision(newtonbody);

		dFloat shapeVolume = NewtonConvexCollisionCalculateVolume(collision);
		if (shapeVolume > 0.0f)
		{
			dFloat fluidDentity = 1.0f / (m_waterToSolidVolumeRatio * shapeVolume);
			dFloat viscosity = 0.990f;

			//dFloat NewtonConvexCollisionCalculateBuoyancyVolume(const NewtonCollision* const convexCollision, const dFloat* const matrix, const dFloat* const fluidPlane, dFloat* const centerOfBuoyancy)
			//NewtonConvexCollisionCalculateBuoyancyAcceleration(collision, &matrix[0][0], &cog[0], &gravity[0], &m_plane[0], fluidDentity, viscosity, &accelPerUnitMass[0], &torquePerUnitMass[0]);

			dVector force(accelPerUnitMass.Scale(mass));
			dVector torque(torquePerUnitMass.Scale(mass));

			dVector omega(0.0f);
			NewtonBodyGetOmega(newtonbody, &omega[0]);
			omega = omega.Scale(viscosity);
			NewtonBodySetOmega(newtonbody, &omega[0]);
			NewtonBodyGetVelocity(newtonbody, &omega[0]);
			omega = omega.Scale(viscosity);
			NewtonBodySetVelocity(newtonbody, &omega[0]);

			NewtonBodyAddForce(newtonbody, &force[0]);
			NewtonBodyAddTorque(newtonbody, &torque[0]);
		}
	}
}`

[JulioJerez]

what do you mean is commented out? it is in file
..\newton-3.14\applications\demosSandbox\sdkDemos\demos\ArchimedesBuoyancy.cpp

[Leadwerks]

Okay, there is an example here of how to do this:

newton-dynamics/newton-3.14/applications/demosSandbox/sdkDemos/demos/ArchimedesBuoyancy.cpp

Line 102 in a059c83

void OnInside(NewtonBody* const visitor, dFloat timestep)

Thank you for your answer.