public override void Update(GameTime gameTime)
{
// Update _time.
_time += (float)gameTime.ElapsedGameTime.TotalSeconds;
var debugRenderer = GraphicsScreen.DebugRenderer;
debugRenderer.Clear();
// Draw the path key points.
foreach (var point in _path.Select(key => key.Point))
{
debugRenderer.DrawPoint(point, Color.Black, false);
}
// Draw the path.
for (float i = 0; i < _path.Last().Parameter; i += 0.1f)
{
var point0 = _path.GetPoint(i);
var point1 = _path.GetPoint((i + 0.1f));
debugRenderer.DrawLine(point0, point1, Color.Black, false);
}
// Move an object with constant speed along the path.
const float speed = 2;
var traveledDistance = _time * speed;
// Get path parameter where the path length is equal to traveledDistance.
var parameter = _path.GetParameterFromLength(traveledDistance, 10, 0.01f);
// Get path point at the traveledDistance.
Vector3F position = _path.GetPoint(parameter);
// Get the path tangent at traveledDistance and use it as the forward direction.
Vector3F forward = _path.GetTangent(parameter).Normalized;
// Draw an object on the path.
DrawObject(position, forward);
base.Update(gameTime);
}
private void CreatePath()
{
// Create a cyclic path. (More information on paths can be found in the DigitalRune
// Mathematics documentation and related samples.)
_path = new Path3F
{
SmoothEnds = true,
PreLoop = CurveLoopType.Cycle,
PostLoop = CurveLoopType.Cycle
};
// The curvature of the path is defined by a number of path keys.
_path.Add(new PathKey3F
{
Parameter = 0, // The path parameter defines position of the path key on the curve.
Point = new Vector3(-4, 0.5f, -3), // The world space position of the path key.
Interpolation = SplineInterpolation.CatmullRom, // The type of interpolation that is used between this path key and the next.
});
_path.Add(new PathKey3F
{
Parameter = 1,
Point = new Vector3(-1, 0.5f, -5),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 2,
Point = new Vector3(3, 0.5f, -4),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 3,
Point = new Vector3(0, 0.5f, 0),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 4,
Point = new Vector3(-3, 0.5f, 3),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 5,
Point = new Vector3(-1, 0.5f, 5),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 6,
Point = new Vector3(0, 0.5f, 0),
Interpolation = SplineInterpolation.CatmullRom,
});
// The last key uses the same position as the first key to create a closed path.
PathKey3F lastKey = new PathKey3F
{
Parameter = _path.Count,
Point = _path[0].Point,
Interpolation = SplineInterpolation.CatmullRom,
};
_path.Add(lastKey);
// The current path parameter goes from 0 to 7. This path parameter is not linearly
// proportional to the path length. This is not suitable for animations.
// To move an object with constant speed along a path, the path parameter should
// be linearly proportional to the length of the path.
// ParameterizeByLength() changes the path parameter so that the path parameter
// at the each key is equal to the length of path (measured from the first key position
// to the current key position).
// ParameterizeByLength() uses an iterative process, we end the process after 10
// iterations or when the error is less than 0.01f.
_path.ParameterizeByLength(10, 0.01f);
// Sample the path for rendering.
int numberOfSamples = _pointList.Length - 1;
float pathLength = _path.Last().Parameter;
for (int i = 0; i <= numberOfSamples; i++)
{
Vector3 pointOnPath = _path.GetPoint(pathLength / numberOfSamples * i);
_pointList[i] = pointOnPath;
}
}
private void CreatePath()
{
// Create a cyclic path. (More information on paths can be found in the DigitalRune
// Mathematics documentation and related samples.)
_path = new Path3F
{
SmoothEnds = true,
PreLoop = CurveLoopType.Cycle,
PostLoop = CurveLoopType.Cycle
};
// The curvature of the path is defined by a number of path keys.
_path.Add(new PathKey3F
{
Parameter = 0, // The path parameter defines position of the path key on the curve.
Point = new Vector3F(-4, 0.5f, -3), // The world space position of the path key.
Interpolation = SplineInterpolation.CatmullRom, // The type of interpolation that is used between this path key and the next.
});
_path.Add(new PathKey3F
{
Parameter = 1,
Point = new Vector3F(-1, 0.5f, -5),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 2,
Point = new Vector3F(3, 0.5f, -4),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 3,
Point = new Vector3F(0, 0.5f, 0),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 4,
Point = new Vector3F(-3, 0.5f, 3),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 5,
Point = new Vector3F(-1, 0.5f, 5),
Interpolation = SplineInterpolation.CatmullRom,
});
_path.Add(new PathKey3F
{
Parameter = 6,
Point = new Vector3F(0, 0.5f, 0),
Interpolation = SplineInterpolation.CatmullRom,
});
// The last key uses the same position as the first key to create a closed path.
PathKey3F lastKey = new PathKey3F
{
Parameter = _path.Count,
Point = _path[0].Point,
Interpolation = SplineInterpolation.CatmullRom,
};
_path.Add(lastKey);
// The current path parameter goes from 0 to 7. This path parameter is not linearly
// proportional to the path length. This is not suitable for animations.
// To move an object with constant speed along a path, the path parameter should
// be linearly proportional to the length of the path.
// ParameterizeByLength() changes the path parameter so that the path parameter
// at the each key is equal to the length of path (measured from the first key position
// to the current key position).
// ParameterizeByLength() uses an iterative process, we end the process after 10
// iterations or when the error is less than 0.01f.
_path.ParameterizeByLength(10, 0.01f);
// Sample the path for rendering.
int numberOfSamples = _pointList.Length - 1;
float pathLength = _path.Last().Parameter;
for (int i = 0; i <= numberOfSamples; i++)
{
Vector3F pointOnPath = _path.GetPoint(pathLength / numberOfSamples * i);
_pointList[i] = pointOnPath;
}
}