I modified the friction parameters,but they did not take effect.For xample,A ball is moving,It just gets slower while
colliding with the wall or other things.It has confused me for a long time,and also done many test.But the effect was
unconspicuous.
How to set the friction?And maybe there are other things which bring this kind of problem.
Thans.
yuyang
How do you set the ball to move ? Are you applying some kind of force to the ball ? Do you want to set the friction on the ball or the ground ?
You can set the friction (static and dynamic) of the ball as follows.
{
SphereShapeProperties property = new SphereShapeProperties();property.Radius = 1.0f;
property.MassDensity.Density = 1.5f;
property.Material.DynamicFriction = 0.1f;
property.Material.StaticFriction = 0.1f;
Shape sphere = new SphereShape(property);SingleShapeEntity ball =
new SingleShapeEntity(sphere, null);ball.State.Name =
"Ball";ball.State.Pose.Position = new Vector3(0, 0, 0);
}
To set the friction on the ground, this is what you can do. The code indicates a dynamic and static fricition of 0.5 newtons.
void
AddGround(){
// create a large horizontal plane, at zero elevation. HeightFieldEntity ground = new HeightFieldEntity( "simple ground", // name "03RamieSc.dds", // texture image new MaterialProperties("ground",0.2f,
// restitution0.5f,
// dynamic friction0.5f)
// static friction);
SimulationEngine.GlobalInstancePort.Insert(ground);}
Let me know if you still need help.
Courageous
Hi,Courageous
I make a robot hit the ball,and then the ball moves.But it rotates at the same speed,just like I said before.
I have set the friction,but it seems to be not work.
yuyang
Thank you for your help.
The mass of ball is increased,but ....
Now I think why the friction do not work.There are three parameters which we set,aren't there?Any other
parameters?Is there something else causing this problem..
yuyang
The ball:
private void AddBall()
{
SphereShapeProperties cSphereShape = null;
cSphereShape = new SphereShapeProperties(0.5f, new Pose(new Vector3(0f, 0f, 0f)), 0.02f);
cSphereShape.Material = new MaterialProperties("bphere", 0.5f, 1f, 10f);
cSphereShape.DiffuseColor = new Vector4(0.9f, 0.3f, 0.1f, 1.0f);
_state.ball = new SingleShapeEntity(new SphereShape(cSphereShape), new Vector3(1.1f, 0.1f, 0.45f));
_state.ball.State.Name = "Ball";
SimulationEngine.GlobalInstancePort.Insert(_state.ball);
}
The field:
private void AddField()
{
BoxShapeProperties cprop = new BoxShapeProperties(
0.0f, // mass in kilograms.
new Pose(new Vector3(0.0f, 0.0f, 0.0f)), // relative pose
new Vector3(3.0f, 0.002f, 2.0f));
cprop.Material = new MaterialProperties("cprop", 0.5f, 0.5f, 0.5f);
SingleShapeEntity field = new SingleShapeEntity(
new BoxShape(cprop),
new Vector3(1.0f, 0.002f, 0.9f - 0.0125f));
field.State.Assets.Mesh = "field.obj";
field.BoxShape.State.DiffuseColor = new Vector4(0.0f, 0.0f, 0.0f, 1.0f);
field.State.Name = "field";
SimulationEngine.GlobalInstancePort.Insert(field);
}
That are my code snippets above.Please help me modify them to solve the problem.
Thanks!
yuyang
Changing the friction won't have a significant effect on the rotation of the ball unless the ball is skidding across the ground rather than rolling. When the ball is rolling, it loses very little (if any) energy due to its friction with the ground, it loses nearly all of its energy due to air resistance. Unfortunately, the Ageia engine does not model air resistance.
They have included a parameter that will help, though. You can specify angular and positional damping parameters which will damp the motion of the ball and eventually cause it to stop. For any entity, you can set the following:
State.MassDensity.LinearDamping = 0.05f
and it will provide drag on the linear movement of the entity. In the case of a ball, it will cause it to eventually stop rolling. Ageia doesn't provide a good description for the value that damping should be set to so you will have to experiment with different values until you find something that seems realistic.
-Kyle
