projects/openmelee: ai/steer.d comparison

comparison ai/steer.d @ 18:7f74e064dad5

refactored code

author	zzzzrrr <mason.green@gmail.com>
date	Wed, 25 Mar 2009 11:28:25 -0400
parents	steer.d@8e6a9e390cba
children	08ddf9e71b88

comparison

equal deleted inserted replaced

-:82efafc87d54
+:7f74e064dad5
+/*
+* Copyright (c) 2009, Mason Green (zzzzrrr)
+* http://www.dsource.org/projects/openmelee
+* Based on OpenSteer, Copyright (c) 2002-2003, Sony Computer Entertainment America
+* Original author: Craig Reynolds
+*
+* All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without modification,
+* are permitted provided that the following conditions are met:
+*
+* * Redistributions of source code must retain the above copyright notice,
+*   this list of conditions and the following disclaimer.
+* * Redistributions in binary form must reproduce the above copyright notice,
+*   this list of conditions and the following disclaimer in the documentation
+*   and/or other materials provided with the distribution.
+* * Neither the name of the polygonal nor the names of its contributors may be
+*   used to endorse or promote products derived from this software without specific
+*   prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+module openmelee.ai.steer;
+import blaze.common.bzMath: bzDot, bzClamp, bzVec2;
+import blaze.dynamics.bzBody: bzBody;
+import openmelee.ships.ship : Ship, State;
+import openmelee.ai.utilities;
+class Steer
+{
+// Constructor: initializes state
+this (Ship ship)
+{
+m_ship = ship;
+}
+	struct PathIntersection
+{
+bool intersect;
+float distance;
+bzVec2 surfacePoint;
+bzVec2 surfaceNormal;
+bzBody obstacle;
+}
+// reset state
+void reset () {
+// initial state of wander behavior
+m_wanderSide = 0;
+m_wanderUp = 0;
+}
+void update() {
+m_position = m_ship.state.position;
+m_velocity = m_ship.state.velocity;
+m_speed = m_ship.state.speed;
+m_maxForce = m_ship.state.maxForce;
+m_forward = m_ship.state.forward;
+}
+// -------------------------------------------------- steering behaviors
+bzVec2 steerForWander (float dt) {
+// random walk m_wanderSide and m_wanderUp between -1 and +1
+float speed = 12 * dt; // maybe this (12) should be an argument?
+m_wanderSide = scalarRandomWalk (m_wanderSide, speed, -1, +1);
+m_wanderUp   = scalarRandomWalk (m_wanderUp,   speed, -1, +1);
+// return a pure lateral steering vector: (+/-Side) + (+/-Up)
+return (m_side * m_wanderSide) + (m_up * m_wanderUp);
+}
+// Seek behavior
+bzVec2 steerForSeek (bzVec2 target) {
+bzVec2 desiredVelocity = target - m_position;
+return desiredVelocity - m_velocity;
+}
+// Flee behavior
+bzVec2 steerForFlee (bzVec2 target) {
+bzVec2 desiredVelocity = m_position - target;
+return desiredVelocity - m_velocity;
+}
+/*
+// xxx proposed, experimental new seek/flee [cwr 9-16-02]
+bzVec2 xxxsteerForFlee (bzVec2 target) {
+bzVec2 offset = m_position - target;
+bzVec2 desiredVelocity = bzClamp(offset.truncateLength (maxSpeed ());
+return desiredVelocity - m_velocity;
+}
+bzVec2 xxxsteerForSeek (bzVec2 target) {
+//  bzVec2 offset = target - position;
+bzVec2 offset = target - m_position;
+bzVec2 desiredVelocity = offset.truncateLength (maxSpeed ()); //xxxnew
+return desiredVelocity - m_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);
+return avoidance;
+}
+// avoids all obstacles in an ObstacleGroup
+*/
+bzVec2 steerToAvoidObstacles (float minTimeToCollision, bzBody obstacles) {
+bzVec2 avoidance;
+PathIntersection nearest, next;
+float minDistanceToCollision = minTimeToCollision * m_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 (bzBody o; o; o = o.next) {
+// This code which presumes the obstacle is spherical
+//findNextIntersectionWithSphere (o, next);
+if (!nearest.intersect || (next.intersect && next.distance < nearest.distance)) {
+					nearest = next;
+}
+}
+// when a nearest intersection was found
+if (nearest.intersect && (nearest.distance < 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 = m_position - nearest.obstacle.position;
+//avoidance = Vector3Helpers.PerpendicularComponent(offset, this.Forward);
+avoidance.normalize;
+avoidance *= m_maxForce;
+avoidance += m_forward * m_maxForce * 0.75f;
+}
+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;
+// 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 !is 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 = m_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 - m_position;
+float sideDot = offset.dot(m_side());
+steer = (sideDot > 0) ? -1.0f : 1.0f;
+}
+else
+{
+if (parallelness > angle)
+{
+// parallel paths: steer away from threat
+bzVec2 offset = threat.position - m_position;
+float sideDot = bzDot(offset, m_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 = bzDot(m_side, threat.velocity);
+steer = (sideDot > 0) ? -1.0f : 1.0f;
+}
+}
+}
+}
+return m_side() * steer;
+}
+	*/
+// Given two vehicles, based on their current positions and velocities,
+// determine the time until nearest approach
+float predictNearestApproachTime (State other) {
+// imagine we are at the origin with no velocity,
+// compute the relative velocity of the other vehicle
+bzVec2 myVelocity = m_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 = m_position - other.position;
+float projection = bzDot(relTangent, 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 (State other, float time) {
+bzVec2 myTravel =  m_forward *  m_speed * time;
+bzVec2 otherTravel = other.forward * other.speed * time;
+bzVec2 myFinal =  m_position + myTravel;
+bzVec2 otherFinal = other.position + otherTravel;
+return (myFinal - otherFinal).length;
+}
+// ------------------------------------------------------------------------
+// pursuit of another vehicle ( version with ceiling on prediction time)
+bzVec2 steerForPursuit (State quarry) {
+return steerForPursuit (quarry, float.max);
+}
+bzVec2 steerForPursuit (State quarry, float maxPredictionTime) {
+// offset from this to quarry, that distance, unit vector toward quarry
+bzVec2 offset = quarry.position - m_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 = bzDot(m_forward , 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 = bzDot(m_forward , unitOffset);
+float directTravelTime = distance / m_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
+// 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;
+break;
+case 0:           // ahead, perpendicular
+timeFactor = 1.8f;
+break;
+case -1:          // ahead, anti-parallel
+timeFactor = 0.85f;
+break;
+}
+break;
+case 0:
+switch (p)
+{
+case +1:          // aside, parallel
+timeFactor = 1;
+break;
+case 0:           // aside, perpendicular
+timeFactor = 0.8f;
+break;
+case -1:          // aside, anti-parallel
+timeFactor = 4;
+break;
+}
+break;
+case -1:
+switch (p)
+{
+case +1:          // behind, parallel
+timeFactor = 0.5f;
+break;
+case 0:           // behind, perpendicular
+timeFactor = 2;
+break;
+case -1:          // behind, anti-parallel
+timeFactor = 2;
+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);
+return target; //steerForSeek (target);
+}
+// ------------------------------------------------------------------------
+// evasion of another vehicle
+bzVec2 steerForEvasion (State menace,  float maxPredictionTime)  {
+// offset from this to menace, that distance, unit vector toward menace
+bzVec2 offset = menace.position - m_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 = m_maxForce;
+float speedError = targetSpeed - m_speed;
+return m_forward * bzClamp(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 - m_position;
+targetDirection.normalize();
+return bzDot(m_forward, targetDirection) > cosThreshold;
+}
+bool isAside (bzVec2 target, float cosThreshold)
+{
+bzVec2 targetDirection = target - m_position;
+targetDirection.normalize();
+float dp = bzDot(m_forward, targetDirection);
+return (dp < cosThreshold) && (dp > -cosThreshold);
+}
+bool isBehind (bzVec2 target, float cosThreshold)
+{
+bzVec2 targetDirection = target - m_position;
+targetDirection.normalize();
+return bzDot(m_forward, targetDirection) < cosThreshold;
+}
+private:
+Ship m_ship;
+bzVec2 m_position;
+bzVec2 m_velocity;
+bzVec2 m_up;
+bzVec2 m_side;
+bzVec2 m_forward;
+	float m_speed = 0;
+	float m_maxForce = 0;
+// Wander behavior
+float m_wanderSide;
+float m_wanderUp;
+}

Mercurial > projects > openmelee

comparison ai/steer.d @ 18:7f74e064dad5