/**
* <summary>Computes the new velocity of this agent.</summary>
*/
internal void computeNewVelocity()
{
orcaLines_.Clear();
float invTimeHorizonObst = 1.0f / timeHorizonObst_;
/* Create obstacle ORCA lines. */
for (int i = 0; i < obstacleNeighbors_.Count; ++i)
{
Obstacle obstacle1 = obstacleNeighbors_[i].Value;
Obstacle obstacle2 = obstacle1.next_;
Vector2 relativePosition1 = obstacle1.point_ - position_;
Vector2 relativePosition2 = obstacle2.point_ - position_;
/*
* Check if velocity obstacle of obstacle is already taken care
* of by previously constructed obstacle ORCA lines.
*/
bool alreadyCovered = false;
for (int j = 0; j < orcaLines_.Count; ++j)
{
if (RVOMath.det(invTimeHorizonObst * relativePosition1 - orcaLines_[j].point, orcaLines_[j].direction) - invTimeHorizonObst * radius_ >= -RVOMath.RVO_EPSILON && RVOMath.det(invTimeHorizonObst * relativePosition2 - orcaLines_[j].point, orcaLines_[j].direction) - invTimeHorizonObst * radius_ >= -RVOMath.RVO_EPSILON)
{
alreadyCovered = true;
break;
}
}
if (alreadyCovered)
{
continue;
}
/* Not yet covered. Check for collisions. */
float distSq1 = RVOMath.absSq(relativePosition1);
float distSq2 = RVOMath.absSq(relativePosition2);
float radiusSq = RVOMath.sqr(radius_);
Vector2 obstacleVector = obstacle2.point_ - obstacle1.point_;
float s = (-relativePosition1 * obstacleVector) / RVOMath.absSq(obstacleVector);
float distSqLine = RVOMath.absSq(-relativePosition1 - s * obstacleVector);
Line line;
if (s < 0.0f && distSq1 <= radiusSq)
{
/* Collision with left vertex. Ignore if non-convex. */
if (obstacle1.convex_)
{
line.point = new Vector2(0.0f, 0.0f);
line.direction = RVOMath.normalize(new Vector2(-relativePosition1.y(), relativePosition1.x()));
orcaLines_.Add(line);
}
continue;
}
else if (s > 1.0f && distSq2 <= radiusSq)
{
/*
* Collision with right vertex. Ignore if non-convex or if
* it will be taken care of by neighboring obstacle.
*/
if (obstacle2.convex_ && RVOMath.det(relativePosition2, obstacle2.direction_) >= 0.0f)
{
line.point = new Vector2(0.0f, 0.0f);
line.direction = RVOMath.normalize(new Vector2(-relativePosition2.y(), relativePosition2.x()));
orcaLines_.Add(line);
}
continue;
}
else if (s >= 0.0f && s < 1.0f && distSqLine <= radiusSq)
{
/* Collision with obstacle segment. */
line.point = new Vector2(0.0f, 0.0f);
line.direction = -obstacle1.direction_;
orcaLines_.Add(line);
continue;
}
/*
* No collision. Compute legs. When obliquely viewed, both legs
* can come from a single vertex. Legs extend cut-off line when
* non-convex vertex.
*/
Vector2 leftLegDirection, rightLegDirection;
if (s < 0.0f && distSqLine <= radiusSq)
{
/*
* Obstacle viewed obliquely so that left vertex
* defines velocity obstacle.
*/
if (!obstacle1.convex_)
{
/* Ignore obstacle. */
continue;
}
obstacle2 = obstacle1;
float leg1 = RVOMath.sqrt(distSq1 - radiusSq);
leftLegDirection = new Vector2(relativePosition1.x() * leg1 - relativePosition1.y() * radius_, relativePosition1.x() * radius_ + relativePosition1.y() * leg1) / distSq1;
rightLegDirection = new Vector2(relativePosition1.x() * leg1 + relativePosition1.y() * radius_, -relativePosition1.x() * radius_ + relativePosition1.y() * leg1) / distSq1;
}
else if (s > 1.0f && distSqLine <= radiusSq)
{
/*
* Obstacle viewed obliquely so that
* right vertex defines velocity obstacle.
*/
if (!obstacle2.convex_)
{
/* Ignore obstacle. */
continue;
}
obstacle1 = obstacle2;
float leg2 = RVOMath.sqrt(distSq2 - radiusSq);
leftLegDirection = new Vector2(relativePosition2.x() * leg2 - relativePosition2.y() * radius_, relativePosition2.x() * radius_ + relativePosition2.y() * leg2) / distSq2;
rightLegDirection = new Vector2(relativePosition2.x() * leg2 + relativePosition2.y() * radius_, -relativePosition2.x() * radius_ + relativePosition2.y() * leg2) / distSq2;
}
else
{
/* Usual situation. */
if (obstacle1.convex_)
{
float leg1 = RVOMath.sqrt(distSq1 - radiusSq);
leftLegDirection = new Vector2(relativePosition1.x() * leg1 - relativePosition1.y() * radius_, relativePosition1.x() * radius_ + relativePosition1.y() * leg1) / distSq1;
}
else
{
/* Left vertex non-convex; left leg extends cut-off line. */
leftLegDirection = -obstacle1.direction_;
}
if (obstacle2.convex_)
{
float leg2 = RVOMath.sqrt(distSq2 - radiusSq);
rightLegDirection = new Vector2(relativePosition2.x() * leg2 + relativePosition2.y() * radius_, -relativePosition2.x() * radius_ + relativePosition2.y() * leg2) / distSq2;
}
else
{
/* Right vertex non-convex; right leg extends cut-off line. */
rightLegDirection = obstacle1.direction_;
}
}
/*
* Legs can never point into neighboring edge when convex
* vertex, take cutoff-line of neighboring edge instead. If
* velocity projected on "foreign" leg, no constraint is added.
*/
Obstacle leftNeighbor = obstacle1.previous_;
bool isLeftLegForeign = false;
bool isRightLegForeign = false;
if (obstacle1.convex_ && RVOMath.det(leftLegDirection, -leftNeighbor.direction_) >= 0.0f)
{
/* Left leg points into obstacle. */
leftLegDirection = -leftNeighbor.direction_;
isLeftLegForeign = true;
}
if (obstacle2.convex_ && RVOMath.det(rightLegDirection, obstacle2.direction_) <= 0.0f)
{
/* Right leg points into obstacle. */
rightLegDirection = obstacle2.direction_;
isRightLegForeign = true;
}
/* Compute cut-off centers. */
Vector2 leftCutOff = invTimeHorizonObst * (obstacle1.point_ - position_);
Vector2 rightCutOff = invTimeHorizonObst * (obstacle2.point_ - position_);
Vector2 cutOffVector = rightCutOff - leftCutOff;
/* Project current velocity on velocity obstacle. */
/* Check if current velocity is projected on cutoff circles. */
float t = obstacle1 == obstacle2 ? 0.5f : ((velocity_ - leftCutOff) * cutOffVector) / RVOMath.absSq(cutOffVector);
float tLeft = (velocity_ - leftCutOff) * leftLegDirection;
float tRight = (velocity_ - rightCutOff) * rightLegDirection;
if ((t < 0.0f && tLeft < 0.0f) || (obstacle1 == obstacle2 && tLeft < 0.0f && tRight < 0.0f))
{
/* Project on left cut-off circle. */
Vector2 unitW = RVOMath.normalize(velocity_ - leftCutOff);
line.direction = new Vector2(unitW.y(), -unitW.x());
line.point = leftCutOff + radius_ * invTimeHorizonObst * unitW;
orcaLines_.Add(line);
continue;
}
else if (t > 1.0f && tRight < 0.0f)
{
/* Project on right cut-off circle. */
Vector2 unitW = RVOMath.normalize(velocity_ - rightCutOff);
line.direction = new Vector2(unitW.y(), -unitW.x());
line.point = rightCutOff + radius_ * invTimeHorizonObst * unitW;
orcaLines_.Add(line);
continue;
}
/*
* Project on left leg, right leg, or cut-off line, whichever is
* closest to velocity.
*/
float distSqCutoff = (t <0.0f || t> 1.0f || obstacle1 == obstacle2) ? float.PositiveInfinity : RVOMath.absSq(velocity_ - (leftCutOff + t * cutOffVector));
float distSqLeft = tLeft < 0.0f ? float.PositiveInfinity : RVOMath.absSq(velocity_ - (leftCutOff + tLeft * leftLegDirection));
float distSqRight = tRight < 0.0f ? float.PositiveInfinity : RVOMath.absSq(velocity_ - (rightCutOff + tRight * rightLegDirection));
if (distSqCutoff <= distSqLeft && distSqCutoff <= distSqRight)
{
/* Project on cut-off line. */
line.direction = -obstacle1.direction_;
line.point = leftCutOff + radius_ * invTimeHorizonObst * new Vector2(-line.direction.y(), line.direction.x());
orcaLines_.Add(line);
continue;
}
if (distSqLeft <= distSqRight)
{
/* Project on left leg. */
if (isLeftLegForeign)
{
continue;
}
line.direction = leftLegDirection;
line.point = leftCutOff + radius_ * invTimeHorizonObst * new Vector2(-line.direction.y(), line.direction.x());
orcaLines_.Add(line);
continue;
}
/* Project on right leg. */
if (isRightLegForeign)
{
continue;
}
line.direction = -rightLegDirection;
line.point = rightCutOff + radius_ * invTimeHorizonObst * new Vector2(-line.direction.y(), line.direction.x());
orcaLines_.Add(line);
}
int numObstLines = orcaLines_.Count;
float invTimeHorizon = 1.0f / timeHorizon_;
/* Create agent ORCA lines. */
for (int i = 0; i < agentNeighbors_.Count; ++i)
{
Agent other = agentNeighbors_[i].Value;
Vector2 relativePosition = other.position_ - position_;
Vector2 relativeVelocity = velocity_ - other.velocity_;
float distSq = RVOMath.absSq(relativePosition);
float combinedRadius = radius_ + other.radius_;
float combinedRadiusSq = RVOMath.sqr(combinedRadius);
Line line;
Vector2 u;
if (distSq > combinedRadiusSq)
{
/* No collision. */
Vector2 w = relativeVelocity - invTimeHorizon * relativePosition;
/* Vector from cutoff center to relative velocity. */
float wLengthSq = RVOMath.absSq(w);
float dotProduct1 = w * relativePosition;
if (dotProduct1 < 0.0f && RVOMath.sqr(dotProduct1) > combinedRadiusSq * wLengthSq)
{
/* Project on cut-off circle. */
float wLength = RVOMath.sqrt(wLengthSq);
Vector2 unitW = w / wLength;
line.direction = new Vector2(unitW.y(), -unitW.x());
u = (combinedRadius * invTimeHorizon - wLength) * unitW;
}
else
{
/* Project on legs. */
float leg = RVOMath.sqrt(distSq - combinedRadiusSq);
if (RVOMath.det(relativePosition, w) > 0.0f)
{
/* Project on left leg. */
line.direction = new Vector2(relativePosition.x() * leg - relativePosition.y() * combinedRadius, relativePosition.x() * combinedRadius + relativePosition.y() * leg) / distSq;
}
else
{
/* Project on right leg. */
line.direction = -new Vector2(relativePosition.x() * leg + relativePosition.y() * combinedRadius, -relativePosition.x() * combinedRadius + relativePosition.y() * leg) / distSq;
}
float dotProduct2 = relativeVelocity * line.direction;
u = dotProduct2 * line.direction - relativeVelocity;
}
}
else
{
/* Collision. Project on cut-off circle of time timeStep. */
float invTimeStep = 1.0f / timeStep_;
/* Vector from cutoff center to relative velocity. */
Vector2 w = relativeVelocity - invTimeStep * relativePosition;
float wLength = RVOMath.abs(w);
Vector2 unitW = w / wLength;
line.direction = new Vector2(unitW.y(), -unitW.x());
u = (combinedRadius * invTimeStep - wLength) * unitW;
}
line.point = velocity_ + 0.5f * u;
orcaLines_.Add(line);
}
int lineFail = linearProgram2(orcaLines_, maxSpeed_, prefVelocity_, false, ref newVelocity_);
if (lineFail < orcaLines_.Count)
{
linearProgram3(orcaLines_, numObstLines, lineFail, maxSpeed_, ref newVelocity_);
}
}
/**
* <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 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.RVO_EPSILON)
{
/* 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
{
Vector2 v = (optVelocity - lines[lineNo].point);
float v2 = lines[lineNo].direction * v;
/* 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);
}
