softbody simulation

[Liudeke]

I have a question, softbody simulation, why always jitter

[Liudeke]

online-video-cutter.com.mp4

[Liudeke]

The method I used was XPBDFEM

[janbender]

Can you please provide more info about your simulation? Which settings do you use? Time step size, max iteration count, sub stepping, contact handling, ....

[Liudeke]

//contact ground
private static void CollideSDFKernel(Index1D id, TetSimData data)
{

    float3 predictedPosition = data.Predicted[id];
    float3 normal = new float3(0, 1, 0);
    float d = 0.2f;
    float penetration = d - ILGPUMathExpand.dot(normal, predictedPosition) + 0.2f;
    if (penetration > 0.0f)
    {
        float3 velocity = data.Predicted[id] - data.Positions[id];
        float3 deltaPosition = ILGPUMathExpand.calcCollisionResponse(normal, velocity, penetration);
        predictedPosition += deltaPosition;
    }

    data.Predicted[id] = predictedPosition;
}
public static float3 calcCollisionResponse(float3 normal, float3 velocity, float penetration)
{
    float3 collisionResponse = penetration * normal;
    float3 tangentialDisplacement = velocity - dot(velocity, normal) * normal;
    if (length(tangentialDisplacement) < 0.5f * -penetration)
        collisionResponse += 0.5f * tangentialDisplacement;
    else if (length(tangentialDisplacement) != 0.0f)
        collisionResponse += 0.5f * tangentialDisplacement * XMath.Min((0.3f * -penetration) / length(tangentialDisplacement), 1.0f);

    return collisionResponse;
}


// setting
deltatime 0.001
m_poissonRatio 0.3
max iteration count 1
sub stepping 5