src/bzflag/ShotStrategy.cxx

/* bzflag
 * Copyright (c) 1993-2021 Tim Riker
 *
 * This package is free software;  you can redistribute it and/or
 * modify it under the terms of the license found in the file
 * named COPYING that should have accompanied this file.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* interface header */
#include "ShotStrategy.h"

/* common implementation headers */
#include "CollisionManager.h"
#include "Obstacle.h"
#include "ObstacleList.h"
#include "WallObstacle.h"
#include "ObstacleMgr.h"

ShotStrategy::ShotStrategy(ShotPath* _path) :
    path(_path)
{
    // do nothing
}

ShotStrategy::~ShotStrategy()
{
    // do nothing
}

bool ShotStrategy::isStoppedByHit() const
{
    return true;
}

void ShotStrategy::sendUpdate(const FiringInfo&) const
{
    // do nothing by default -- normal shots don't need updates
}

void ShotStrategy::readUpdate(uint16_t, const void*)
{
    // do nothing by default -- normal shots don't need updates
}

void ShotStrategy::expire()
{
    // do nothing by default
}

void ShotStrategy::setReloadTime(float t) const
{
    path->setReloadTime(t);
}

void ShotStrategy::setPosition(const float* p) const
{
    path->setPosition(p);
}

void ShotStrategy::setVelocity(const float* v) const
{
    path->setVelocity(v);
}

void ShotStrategy::setExpiring() const
{
    path->setExpiring();
}

void ShotStrategy::setExpired() const
{
    path->setExpired();
}

FiringInfo& ShotStrategy::getFiringInfo(ShotPath* p) const
{
    return p->getFiringInfo();
}

const Obstacle* ShotStrategy::getFirstBuilding(const Ray& ray,
        float min, float& t)
{
    const Obstacle* closestObstacle = NULL;
    unsigned int i = 0;

    // check walls
    const ObstacleList& walls = OBSTACLEMGR.getWalls();
    for (i = 0; i < walls.size(); i++)
    {
        const WallObstacle* wall = (const WallObstacle*) walls[i];
        if (!wall->isShootThrough())
        {
            const float wallt = wall->intersect(ray);
            if (wallt > min && wallt < t)
            {
                t = wallt;
                closestObstacle = wall;
            }
        }
    }

    //check everything else
    const ObsList* olist = COLLISIONMGR.rayTest (&ray, t);

    for (i = 0; i < (unsigned int)olist->count; i++)
    {
        const Obstacle* obs = olist->list[i];
        if (!obs->isShootThrough())
        {
            const float timet = obs->intersect(ray);
            if (obs->getType() == Teleporter::getClassName())
            {
                const Teleporter* tele = (const Teleporter*) obs;
                int face;
                if ((timet > min) && (timet < t) &&
                        (tele->isTeleported(ray, face) < 0.0f))
                {
                    t = timet;
                    closestObstacle = obs;
                }
            }
            else
            {
                if ((timet > min) && (timet < t))
                {
                    t = timet;
                    closestObstacle = obs;
                }
            }
        }
    }

    return closestObstacle;
}

void ShotStrategy::reflect(float* v, const float* n) // const
{
    // normal is assumed to be normalized, v needn't be
    float d = -2.0f * ((n[0] * v[0]) + (n[1] * v[1]) + (n[2] * v[2]));

    if (d >= 0.0f)
    {
        // normal reflection
        v[0] += d * n[0];
        v[1] += d * n[1];
        v[2] += d * n[2];
    }
    else
    {
        // refraction due to inverted normal (still using the 2X factor)
        float oldSpeed = sqrtf((v[0] * v[0]) + (v[1] * v[1]) + (v[2] * v[2]));
        d = -2.0f * d; // now using 4X refraction factor
        v[0] += d * n[0];
        v[1] += d * n[1];
        v[2] += d * n[2];
        // keep the same speed as the incoming vector
        float newSpeed = sqrtf((v[0] * v[0]) + (v[1] * v[1]) + (v[2] * v[2]));
        const float scale = (oldSpeed / newSpeed);
        v[0] *= scale;
        v[1] *= scale;
        v[2] *= scale;
    }

    return;
}

const Teleporter* ShotStrategy::getFirstTeleporter(const Ray& ray, float min,
        float& t, int& f) const
{
    const Teleporter* closestTeleporter = NULL;
    int face;

    const ObstacleList& teles = OBSTACLEMGR.getTeles();

    for (unsigned int i = 0; i < teles.size(); i++)
    {
        const Teleporter& tele = *((const Teleporter*) teles[i]);
        const float telet = tele.isTeleported(ray, face);
        if (telet > min && telet < t)
        {
            t = telet;
            f = face;
            closestTeleporter = &tele;
        }
    }

    return closestTeleporter;
}

bool ShotStrategy::getGround(const Ray& r, float min, float &t) const
{
    if (r.getDirection()[2] >= 0.0f)
        return false;

    float groundT = r.getOrigin()[2] / -r.getDirection()[2];
    if ((groundT > min) && (groundT < t))
    {
        t = groundT;
        return true;
    }
    return false;
}


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