/**
* <summary>Solves a two-dimensional linear program subject to linear
* constraints defined by lines and a circular constraint.</summary>
*
* <param name="lines">Lines defining the linear constraints.</param>
* <param name="numObstLines">Count of obstacle lines.</param>
* <param name="beginLine">The line on which the 2-d linear program
* failed.</param>
* <param name="radius">The radius of the circular constraint.</param>
* <param name="result">A reference to the result of the linear program.
* </param>
*/
private static void LinearProgram3(IList <Line> lines, int numObstLines, int beginLine, float radius, ref Vector2 result)
{
float distance = 0.0f;
for (int i = beginLine; i < lines.Count; ++i)
{
if (RVOMath.Det(lines[i].Direction, lines[i].Point - result) > distance)
{
/* Result does not satisfy constraint of line i. */
IList <Line> projLines = new List <Line>();
for (int ii = 0; ii < numObstLines; ++ii)
{
projLines.Add(lines[ii]);
}
for (int j = numObstLines; j < i; ++j)
{
Line line;
float determinant = RVOMath.Det(lines[i].Direction, lines[j].Direction);
if (RVOMath.Fabs(determinant) <= RVOMath.RvoEpsilon)
{
/* Line i and line j are parallel. */
if (lines[i].Direction * lines[j].Direction > 0.0f)
{
/* Line i and line j point in the same direction. */
continue;
}
else
{
/* Line i and line j point in opposite direction. */
line.Point = 0.5f * (lines[i].Point + lines[j].Point);
}
}
else
{
line.Point = lines[i].Point + (RVOMath.Det(lines[j].Direction, lines[i].Point - lines[j].Point) / determinant) * lines[i].Direction;
}
line.Direction = RVOMath.Normalize(lines[j].Direction - lines[i].Direction);
projLines.Add(line);
}
Vector2 tempResult = result;
if (LinearProgram2(projLines, radius, new Vector2(-lines[i].Direction.Y, lines[i].Direction.X), true, ref result) < projLines.Count)
{
/*
* This should in principle not happen. The result is by
* definition already in the feasible region of this
* linear program. If it fails, it is due to small
* floating point error, and the current result is kept.
*/
result = tempResult;
}
distance = RVOMath.Det(lines[i].Direction, lines[i].Point - result);
}
}
}
/**
* <summary>Solves a one-dimensional linear program on a specified line
* subject to linear constraints defined by lines and a circular
* constraint.</summary>
*
* <returns>True if successful.</returns>
*
* <param name="lines">Lines defining the linear constraints.</param>
* <param name="lineNo">The specified line constraint.</param>
* <param name="radius">The radius of the circular constraint.</param>
* <param name="optVelocity">The optimization velocity.</param>
* <param name="directionOpt">True if the direction should be optimized.
* </param>
* <param name="result">A reference to the result of the linear program.
* </param>
*/
private static bool LinearProgram1(IList <Line> lines, int lineNo, float radius, Vector2 optVelocity, bool directionOpt, ref Vector2 result)
{
float dotProduct = lines[lineNo].Point * lines[lineNo].Direction;
float discriminant = RVOMath.Sqr(dotProduct) + RVOMath.Sqr(radius) - RVOMath.AbsSq(lines[lineNo].Point);
if (discriminant < 0.0f)
{
/* Max speed circle fully invalidates line lineNo. */
return(false);
}
float sqrtDiscriminant = RVOMath.Sqrt(discriminant);
float tLeft = -dotProduct - sqrtDiscriminant;
float tRight = -dotProduct + sqrtDiscriminant;
for (int i = 0; i < lineNo; ++i)
{
float denominator = RVOMath.Det(lines[lineNo].Direction, lines[i].Direction);
float numerator = RVOMath.Det(lines[i].Direction, lines[lineNo].Point - lines[i].Point);
if (RVOMath.Fabs(denominator) <= RVOMath.RvoEpsilon)
{
/* Lines lineNo and i are (almost) parallel. */
if (numerator < 0.0f)
{
return(false);
}
continue;
}
float t = numerator / denominator;
if (denominator >= 0.0f)
{
/* Line i bounds line lineNo on the right. */
tRight = Math.Min(tRight, t);
}
else
{
/* Line i bounds line lineNo on the left. */
tLeft = Math.Max(tLeft, t);
}
if (tLeft > tRight)
{
return(false);
}
}
if (directionOpt)
{
/* Optimize direction. */
if (optVelocity * lines[lineNo].Direction > 0.0f)
{
/* Take right extreme. */
result = lines[lineNo].Point + tRight * lines[lineNo].Direction;
}
else
{
/* Take left extreme. */
result = lines[lineNo].Point + tLeft * lines[lineNo].Direction;
}
}
else
{
/* Optimize closest point. */
float t = lines[lineNo].Direction * (optVelocity - lines[lineNo].Point);
if (t < tLeft)
{
result = lines[lineNo].Point + tLeft * lines[lineNo].Direction;
}
else if (t > tRight)
{
result = lines[lineNo].Point + tRight * lines[lineNo].Direction;
}
else
{
result = lines[lineNo].Point + t * lines[lineNo].Direction;
}
}
return(true);
}
