projects/openmelee: steer.d comparison

comparison steer.d @ 0:c10bc63824e7

Initial commit!

author	zzzzrrr <mason.green@gmail.com>
date	Fri, 20 Mar 2009 06:41:25 -0400
parents
children	a40d066ebbd1

comparison

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--1:000000000000
+:c10bc63824e7
+// ----------------------------------------------------------------------------
+//
+//
+// OpenSteer -- Steering Behaviors for Autonomous Characters
+//
+// Copyright (c) 2002-2003, Sony Computer Entertainment America
+// Original author: Craig Reynolds <craig_reynolds@playstation.sony.com>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+//
+// ----------------------------------------------------------------------------
+//
+//
+// SteerLibraryMixin
+//
+// This mixin (class with templated superclass) adds the "steering library"
+// functionality to a given base class.  SteerLibraryMixin assumes its base
+// class supports the Ship interface.
+//
+// 10-04-04 bk:  put everything into the OpenSteer namespace
+// 02-06-03 cwr: create mixin (from "SteerMass")
+// 06-03-02 cwr: removed TS dependencies
+// 11-21-01 cwr: created
+//
+//
+// ----------------------------------------------------------------------------
+module melee.steer;
+class Steer
+{
+// Constructor: initializes state
+this ()
+{
+// set inital state
+reset ();
+}
+// reset state
+void reset (void)
+{
+// initial state of wander behavior
+wanderSide = 0;
+wanderUp = 0;
+// default to non-gaudyPursuitAnnotation
+gaudyPursuitAnnotation = false;
+}
+// -------------------------------------------------- steering behaviors
+// Wander behavior
+float wanderSide;
+float wanderUp;
+bzVec2 steerForWander (float dt) {
+// random walk wanderSide and wanderUp between -1 and +1
+float speed = 12 * dt; // maybe this (12) should be an argument?
+wanderSide = scalarRandomWalk (wanderSide, speed, -1, +1);
+wanderUp   = scalarRandomWalk (wanderUp,   speed, -1, +1);
+// return a pure lateral steering vector: (+/-Side) + (+/-Up)
+return (side() * wanderSide) + (up() * wanderUp);
+}
+// Seek behavior
+bzVec2 steerForSeek (bzVec2 target) {
+bzVec2 desiredVelocity = target - position;
+return desiredVelocity - velocity;
+}
+// Flee behavior
+bzVec2 steerForFlee (bzVec2 target) {
+bzVec2 desiredVelocity = position - target;
+return desiredVelocity - velocity();
+}
+// xxx proposed, experimental new seek/flee [cwr 9-16-02]
+bzVec2 xxxsteerForFlee (bzVec2 target) {
+bzVec2 offset = position - target;
+bzVec2 desiredVelocity = offset.truncateLength (maxSpeed ());
+return desiredVelocity - velocity();
+}
+bzVec2 xxxsteerForSeek (bzVec2 target) {
+//  bzVec2 offset = target - position;
+bzVec2 offset = target - position;
+bzVec2 desiredVelocity = offset.truncateLength (maxSpeed ()); //xxxnew
+return desiredVelocity - velocity();
+}
+// ------------------------------------------------------------------------
+// Obstacle Avoidance behavior
+//
+// Returns a steering force to avoid a given obstacle.  The purely
+// lateral steering force will turn our vehicle towards a silhouette edge
+// of the obstacle.  Avoidance is required when (1) the obstacle
+// intersects the vehicle's current path, (2) it is in front of the
+// vehicle, and (3) is within minTimeToCollision seconds of travel at the
+// vehicle's current velocity.  Returns a zero vector value (bzVec2::zero)
+// when no avoidance is required.
+bzVec2 steerToAvoidObstacle (float minTimeToCollision, Obstacle obstacle) {
+bzVec2 avoidance = obstacle.steerToAvoid (this, minTimeToCollision);
+// XXX more annotation modularity problems (assumes spherical obstacle)
+if (avoidance != bzVec2::zero)
+annotateAvoidObstacle (minTimeToCollision * speed());
+return avoidance;
+}
+// avoids all obstacles in an ObstacleGroup
+bzVec2 steerToAvoidObstacles (float minTimeToCollision,
+ObstacleGroup obstacles) {
+bzVec2 avoidance;
+PathIntersection nearest, next;
+float minDistanceToCollision = minTimeToCollision * speed();
+next.intersect = false;
+nearest.intersect = false;
+// test all obstacles for intersection with my forward axis,
+// select the one whose point of intersection is nearest
+for (ObstacleIterator o = obstacles.begin(); o != obstacles.end(); o++)
+{
+// xxx this should be a generic call on Obstacle, rather than
+// xxx this code which presumes the obstacle is spherical
+findNextIntersectionWithSphere ((SphericalObstacle)**o, next);
+if ((nearest.intersect == false) ||
+((next.intersect != false)
+(next.distance < nearest.distance)))
+nearest = next;
+}
+// when a nearest intersection was found
+if ((nearest.intersect != false)
+(nearest.distance < minDistanceToCollision))
+{
+// show the corridor that was checked for collisions
+annotateAvoidObstacle (minDistanceToCollision);
+// compute avoidance steering force: take offset from obstacle to me,
+// take the component of that which is lateral (perpendicular to my
+// forward direction), set length to maxForce, add a bit of forward
+// component (in capture the flag, we never want to slow down)
+bzVec2 offset = position - nearest.obstacle.center;
+avoidance = offset.perpendicularComponent (forward());
+avoidance = avoidance.normalize ();
+avoidance *= maxForce ();
+avoidance += forward() * maxForce () * 0.75;
+}
+return avoidance;
+}
+// ------------------------------------------------------------------------
+// Unaligned collision avoidance behavior: avoid colliding with other
+// nearby vehicles moving in unconstrained directions.  Determine which
+// (if any) other other vehicle we would collide with first, then steers
+// to avoid the site of that potential collision.  Returns a steering
+// force vector, which is zero length if there is no impending collision.
+bzVec2 steerToAvoidNeighbors (float minTimeToCollision, AVGroup others) {
+// first priority is to prevent immediate interpenetration
+bzVec2 separation = steerToAvoidCloseNeighbors (0, others);
+if (separation != bzVec2::zero) return separation;
+// otherwise, go on to consider potential future collisions
+float steer = 0;
+Ship* threat = NULL;
+// Time (in seconds) until the most immediate collision threat found
+// so far.  Initial value is a threshold: don't look more than this
+// many frames into the future.
+float minTime = minTimeToCollision;
+// xxx solely for annotation
+bzVec2 xxxThreatPositionAtNearestApproach;
+bzVec2 xxxOurPositionAtNearestApproach;
+// for each of the other vehicles, determine which (if any)
+// pose the most immediate threat of collision.
+for (AVIterator i = others.begin(); i != others.end(); i++)
+{
+Ship other = **i;
+if (other != this)
+{
+// avoid when future positions are this close (or less)
+float collisionDangerThreshold = radius() * 2;
+// predicted time until nearest approach of "this" and "other"
+float time = predictNearestApproachTime (other);
+// If the time is in the future, sooner than any other
+// threatened collision...
+if ((time >= 0)  (time < minTime))
+{
+// if the two will be close enough to collide,
+// make a note of it
+if (computeNearestApproachPositions (other, time)
+< collisionDangerThreshold)
+{
+minTime = time;
+threat = other;
+xxxThreatPositionAtNearestApproach
+= hisPositionAtNearestApproach;
+xxxOurPositionAtNearestApproach
+= ourPositionAtNearestApproach;
+}
+}
+}
+}
+// if a potential collision was found, compute steering to avoid
+if (threat)
+{
+// parallel: +1, perpendicular: 0, anti-parallel: -1
+float parallelness = forward.dot(threat.forward);
+float angle = 0.707f;
+if (parallelness < -angle)
+{
+// anti-parallel "head on" paths:
+// steer away from future threat position
+bzVec2 offset = xxxThreatPositionAtNearestApproach - position;
+float sideDot = offset.dot(side());
+steer = (sideDot > 0) ? -1.0f : 1.0f;
+}
+else
+{
+if (parallelness > angle)
+{
+// parallel paths: steer away from threat
+bzVec2 offset = threat.position - position;
+float sideDot = offset.dot(side());
+steer = (sideDot > 0) ? -1.0f : 1.0f;
+}
+else
+{
+// perpendicular paths: steer behind threat
+// (only the slower of the two does this)
+if (threat.speed() <= speed())
+{
+float sideDot = side().dot(threat.velocity);
+steer = (sideDot > 0) ? -1.0f : 1.0f;
+}
+}
+}
+}
+return side() * steer;
+}
+// Given two vehicles, based on their current positions and velocities,
+// determine the time until nearest approach
+float predictNearestApproachTime (Ship other) {
+// imagine we are at the origin with no velocity,
+// compute the relative velocity of the other vehicle
+bzVec2 myVelocity = velocity;
+bzVec2 otherVelocity = other.velocity;
+bzVec2 relVelocity = otherVelocity - myVelocity;
+float relSpeed = relVelocity.length;
+// for parallel paths, the vehicles will always be at the same distance,
+// so return 0 (aka "now") since "there is no time like the present"
+if (relSpeed == 0) return 0;
+// Now consider the path of the other vehicle in this relative
+// space, a line defined by the relative position and velocity.
+// The distance from the origin (our vehicle) to that line is
+// the nearest approach.
+// Take the unit tangent along the other vehicle's path
+bzVec2 relTangent = relVelocity / relSpeed;
+// find distance from its path to origin (compute offset from
+// other to us, find length of projection onto path)
+bzVec2 relPosition = position - other.position;
+float projection = relTangent.dot(relPosition);
+return projection / relSpeed;
+}
+// Given the time until nearest approach (predictNearestApproachTime)
+// determine position of each vehicle at that time, and the distance
+// between them
+float computeNearestApproachPositions (Ship other, float time) {
+bzVec2 myTravel =  forward *  speed * time;
+bzVec2 otherTravel = other.forward * other.speed * time;
+bzVec2 myFinal =  position + myTravel;
+bzVec2 otherFinal = other.position + otherTravel;
+// xxx for annotation
+ourPositionAtNearestApproach = myFinal;
+hisPositionAtNearestApproach = otherFinal;
+return bzVec2::distance (myFinal, otherFinal);
+}
+// otherwise return zero
+return bzVec2::zero;
+}
+// ------------------------------------------------------------------------
+// pursuit of another vehicle ( version with ceiling on prediction time)
+bzVec2 steerForPursuit (Ship quarry) {
+return steerForPursuit (quarry, FLT_MAX);
+}
+bzVec2 steerForPursuit (Ship quarry, float maxPredictionTime) {
+// offset from this to quarry, that distance, unit vector toward quarry
+bzVec2 offset = quarry.position - position;
+float distance = offset.length ();
+bzVec2 unitOffset = offset / distance;
+// how parallel are the paths of "this" and the quarry
+// (1 means parallel, 0 is pependicular, -1 is anti-parallel)
+float parallelness = forward.dot(quarry.forward());
+// how "forward" is the direction to the quarry
+// (1 means dead ahead, 0 is directly to the side, -1 is straight back)
+float forwardness = forward.dot(unitOffset);
+float directTravelTime = distance / speed;
+int f = intervalComparison (forwardness,  -0.707f, 0.707f);
+int p = intervalComparison (parallelness, -0.707f, 0.707f);
+float timeFactor = 0; // to be filled in below
+bzVec2 color;           // to be filled in below (xxx just for debugging)
+// Break the pursuit into nine cases, the cross product of the
+// quarry being [ahead, aside, or behind] us and heading
+// [parallel, perpendicular, or anti-parallel] to us.
+switch (f)
+{
+case +1:
+switch (p)
+{
+case +1:          // ahead, parallel
+timeFactor = 4;
+color = gBlack;
+break;
+case 0:           // ahead, perpendicular
+timeFactor = 1.8f;
+color = gGray50;
+break;
+case -1:          // ahead, anti-parallel
+timeFactor = 0.85f;
+color = gWhite;
+break;
+}
+break;
+case 0:
+switch (p)
+{
+case +1:          // aside, parallel
+timeFactor = 1;
+color = gRed;
+break;
+case 0:           // aside, perpendicular
+timeFactor = 0.8f;
+color = gYellow;
+break;
+case -1:          // aside, anti-parallel
+timeFactor = 4;
+color = gGreen;
+break;
+}
+break;
+case -1:
+switch (p)
+{
+case +1:          // behind, parallel
+timeFactor = 0.5f;
+color= gCyan;
+break;
+case 0:           // behind, perpendicular
+timeFactor = 2;
+color= gBlue;
+break;
+case -1:          // behind, anti-parallel
+timeFactor = 2;
+color = gMagenta;
+break;
+}
+break;
+}
+// estimated time until intercept of quarry
+float et = directTravelTime * timeFactor;
+// xxx experiment, if kept, this limit should be an argument
+float etl = (et > maxPredictionTime) ? maxPredictionTime : et;
+// estimated position of quarry at intercept
+bzVec2 target = quarry.predictFuturePosition (etl);
+// annotation
+annotationLine (position,
+target,
+gaudyPursuitAnnotation ? color : gGray40);
+return steerForSeek (target);
+}
+// ------------------------------------------------------------------------
+// evasion of another vehicle
+bzVec2 steerForEvasion (Ship menace,  float maxPredictionTime)  {
+// offset from this to menace, that distance, unit vector toward menace
+bzVec2 offset = menace.position - position;
+float distance = offset.length;
+float roughTime = distance / menace.speed;
+float predictionTime = ((roughTime > maxPredictionTime) ? maxPredictionTime : roughTime);
+bzVec2 target = menace.predictFuturePosition (predictionTime);
+return steerForFlee (target);
+}
+// ------------------------------------------------------------------------
+// tries to maintain a given speed, returns a maxForce-clipped steering
+// force along the forward/backward axis
+bzVec2 steerForTargetSpeed (float targetSpeed) {
+float mf = maxForce();
+float speedError = targetSpeed - speed ();
+return forward () * clip (speedError, -mf, +mf);
+}
+// ----------------------------------------------------------- utilities
+bool isAhead (bzVec2 target) {return isAhead (target, 0.707f);};
+bool isAside (bzVec2 target) {return isAside (target, 0.707f);};
+bool isBehind (bzVec2 target) {return isBehind (target, -0.707f);};
+bool isAhead (bzVec2 target, float cosThreshold)
+{
+bzVec2 targetDirection = (target - position ()).normalize ();
+return forward().dot(targetDirection) > cosThreshold;
+}
+bool isAside (bzVec2 target, float cosThreshold)
+{
+bzVec2 targetDirection = (target - position ()).normalize ();
+float dp = forward().dot(targetDirection);
+return (dp < cosThreshold)  (dp > -cosThreshold);
+}
+bool isBehind (bzVec2 target, float cosThreshold)
+{
+bzVec2 targetDirection = (target - position).normalize ();
+return forward().dot(targetDirection) < cosThreshold;
+}
+}

Mercurial > projects > openmelee

comparison steer.d @ 0:c10bc63824e7