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+/* Starshatter OpenSource Distribution
+ Copyright (c) 1997-2004, Destroyer Studios LLC.
+ 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 "Destroyer Studios" 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 HOLDER 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.
+
+ SUBSYSTEM: nGenEx.lib
+ FILE: Physical.cpp
+ AUTHOR: John DiCamillo
+
+
+ OVERVIEW
+ ========
+ Abstract Physical Object
+*/
+
+#include "MemDebug.h"
+#include "Physical.h"
+#include "Graphic.h"
+#include "Light.h"
+#include "Director.h"
+
+// +--------------------------------------------------------------------+
+
+int Physical::id_key = 1;
+double Physical::sub_frame = 1.0 / 60.0;
+
+static const double GRAV = 6.673e-11;
+
+// +--------------------------------------------------------------------+
+
+Physical::Physical()
+ : id(id_key++), obj_type(0), rep(0), light(0),
+ thrust(0.0f), drag(0.0f), lat_thrust(false),
+ trans_x(0.0f), trans_y(0.0f), trans_z(0.0f), straight(false),
+ roll(0.0f), pitch(0.0f), yaw(0.0f), dr(0.0f), dp(0.0f), dy(0.0f),
+ dr_acc(0.0f), dp_acc(0.0f), dy_acc(0.0f),
+ dr_drg(0.0f), dp_drg(0.0f), dy_drg(0.0f),
+ flight_path_yaw(0.0f), flight_path_pitch(0.0f), primary_mass(0),
+ roll_rate(1.0f), pitch_rate(1.0f), yaw_rate(1.0f), shake(0.0f),
+ radius(0.0f), mass(1.0f), integrity(1.0f), life(-1), dir(0),
+ g_accel(0.0f), Do(0.0f), CL(0.0f), CD(0.0f), alpha(0.0f), stall(0.0f)
+{
+ strcpy_s(name, "unknown object");
+}
+
+// +--------------------------------------------------------------------+
+
+Physical::Physical(const char* n, int t)
+ : id(id_key++), obj_type(t), rep(0), light(0),
+ thrust(0.0f), drag(0.0f), lat_thrust(false),
+ trans_x(0.0f), trans_y(0.0f), trans_z(0.0f), straight(false),
+ roll(0.0f), pitch(0.0f), yaw(0.0f), dr(0.0f), dp(0.0f), dy(0.0f),
+ dr_acc(0.0f), dp_acc(0.0f), dy_acc(0.0f),
+ dr_drg(0.0f), dp_drg(0.0f), dy_drg(0.0f),
+ flight_path_yaw(0.0f), flight_path_pitch(0.0f), primary_mass(0),
+ roll_rate(1.0f), pitch_rate(1.0f), yaw_rate(1.0f), shake(0.0f),
+ radius(0.0f), mass(1.0f), integrity(1.0f), life(-1), dir(0),
+ g_accel(0.0f), Do(0.0f), CL(0.0f), CD(0.0f), alpha(0.0f), stall(0.0f)
+{
+ strncpy_s(name, n, NAMELEN-1);
+ name[NAMELEN-1] = 0;
+}
+
+// +--------------------------------------------------------------------+
+
+Physical::~Physical()
+{
+ // inform graphic rep and light that we are leaving:
+ GRAPHIC_DESTROY(rep);
+ LIGHT_DESTROY(light);
+
+ // we own the director
+ delete dir;
+ dir = 0;
+}
+
+// +--------------------------------------------------------------------+
+
+inline double random() { return rand()-16384; }
+
+void
+Physical::ExecFrame(double s)
+{
+ Point orig_velocity = Velocity();
+ arcade_velocity = Point();
+
+ // if this object is under direction,
+ // but doesn't need subframe accuracy,
+ // update the control parameters:
+ if (dir && !dir->Subframe())
+ dir->ExecFrame(s);
+
+ // decrement life before destroying the frame time:
+ if (life > 0)
+ life -= s;
+
+ // integrate equations
+ // using slices no larger
+ // than sub_frame:
+
+ double seconds = s;
+
+ while (s > 0.0) {
+ if (s > sub_frame)
+ seconds = sub_frame;
+ else
+ seconds = s;
+
+ // if the director needs subframe accuracy, run it now:
+ if (dir && dir->Subframe())
+ dir->ExecFrame(seconds);
+
+ if (!straight)
+ AngularFrame(seconds);
+
+ // LINEAR MOVEMENT ----------------------------
+ Point pos = cam.Pos();
+
+ // if the object is thrusting,
+ // accelerate along the camera normal:
+ if (thrust) {
+ Point thrustvec = cam.vpn();
+ thrustvec *= ((thrust/mass) * seconds);
+ velocity += thrustvec;
+ }
+
+ LinearFrame(seconds);
+
+ // move the position by the (time-frame scaled) velocity:
+ pos += velocity * seconds;
+ cam.MoveTo(pos);
+
+ s -= seconds;
+ }
+
+ alpha = 0.0f;
+
+ // now update the graphic rep and light sources:
+ if (rep) {
+ rep->MoveTo(cam.Pos());
+ rep->SetOrientation(cam.Orientation());
+ }
+
+ if (light) {
+ light->MoveTo(cam.Pos());
+ }
+
+ if (!straight)
+ CalcFlightPath();
+
+ accel = (Velocity() - orig_velocity) * (1/seconds);
+ if (!_finite(accel.x) || !_finite(accel.y) || !_finite(accel.z))
+ accel = Point();
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::AeroFrame(double s)
+{
+ arcade_velocity = Point();
+
+ // if this object is under direction,
+ // but doesn't need subframe accuracy,
+ // update the control parameters:
+ if (dir && !dir->Subframe())
+ dir->ExecFrame(s);
+
+ // decrement life before destroying the frame time:
+ if (life > 0)
+ life -= s;
+
+ // integrate equations
+ // using slices no larger
+ // than sub_frame:
+
+ double seconds = s;
+
+ while (s > 0.0) {
+ if (s > sub_frame)
+ seconds = sub_frame;
+ else
+ seconds = s;
+
+ // if the director needs subframe accuracy, run it now:
+ if (dir && dir->Subframe())
+ dir->ExecFrame(seconds);
+
+ AngularFrame(seconds);
+
+ // LINEAR MOVEMENT ----------------------------
+ Point pos = cam.Pos();
+
+ // if the object is thrusting,
+ // accelerate along the camera normal:
+ if (thrust) {
+ Point thrustvec = cam.vpn();
+ thrustvec *= ((thrust/mass) * seconds);
+ velocity += thrustvec;
+ }
+
+ // AERODYNAMICS ------------------------------
+
+ if (lat_thrust)
+ LinearFrame(seconds);
+
+ // if no thrusters, do constant gravity:
+ else if (g_accel > 0)
+ velocity += Point(0, -g_accel, 0) * seconds;
+
+ // compute alpha, rho, drag, and lift:
+
+ Point vfp = velocity;
+ double v = vfp.Normalize();
+ double v_2 = 0;
+ double rho = GetDensity();
+ double lift = 0;
+
+ if (v > 150) {
+ v_2 = (v-150) * (v-150);
+
+ Point vfp1 = vfp - cam.vrt() * (vfp * cam.vrt());
+ vfp1.Normalize();
+
+ double cos_alpha = vfp1 * cam.vpn();
+
+ if (cos_alpha >= 1) {
+ alpha = 0.0f;
+ }
+ else {
+ alpha = (float) acos(cos_alpha);
+ }
+
+ // if flight path is above nose, alpha is negative:
+ if (vfp1 * cam.vup() > 0)
+ alpha = -alpha;
+
+ if (alpha <= stall) {
+ lift = CL * alpha * rho * v_2;
+ }
+ else {
+ lift = CL * (2*stall - alpha) * rho * v_2;
+ }
+
+ // add lift to velocity:
+ if (_finite(lift))
+ velocity += cam.vup() * lift * seconds;
+ else
+ lift = 0;
+
+ // if drag applies, decellerate:
+ double alpha_2 = alpha*alpha;
+ double drag_eff = (drag + (CD * alpha_2)) * rho * v_2;
+
+ Point vn = velocity;
+ vn.Normalize();
+
+ velocity += vn * -drag_eff * seconds;
+ }
+ else {
+ velocity *= exp(-drag * seconds);
+ }
+
+ // move the position by the (time-frame scaled) velocity:
+ pos += velocity * seconds;
+ cam.MoveTo(pos);
+
+ s -= seconds;
+ }
+
+ // now update the graphic rep and light sources:
+ if (rep) {
+ rep->MoveTo(cam.Pos());
+ rep->SetOrientation(cam.Orientation());
+ }
+
+ if (light) {
+ light->MoveTo(cam.Pos());
+ }
+}
+
+double
+Physical::GetDensity() const
+{
+ double alt = cam.Pos().y;
+ double rho = 0.75 * Do * (250e3-alt)/250e3;
+
+ return rho;
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::ArcadeFrame(double s)
+{
+ // if this object is under direction,
+ // but doesn't need subframe accuracy,
+ // update the control parameters:
+ if (dir && !dir->Subframe())
+ dir->ExecFrame(s);
+
+ // decrement life before destroying the frame time:
+ if (life > 0)
+ life -= s;
+
+ // integrate equations
+ // using slices no larger
+ // than sub_frame:
+
+ double seconds = s;
+
+ while (s > 0.0) {
+ if (s > sub_frame)
+ seconds = sub_frame;
+ else
+ seconds = s;
+
+ // if the director needs subframe accuracy, run it now:
+ if (dir && dir->Subframe())
+ dir->ExecFrame(seconds);
+
+ if (!straight)
+ AngularFrame(seconds);
+
+ Point pos = cam.Pos();
+
+ // ARCADE FLIGHT MODEL:
+ // arcade_velocity vector is always in line with heading
+
+ double speed = arcade_velocity.Normalize();
+ double bleed = arcade_velocity * cam.vpn();
+
+ speed *= pow(bleed, 30);
+ arcade_velocity = cam.vpn() * speed;
+
+ if (thrust) {
+ Point thrustvec = cam.vpn();
+ thrustvec *= ((thrust/mass) * seconds);
+ arcade_velocity += thrustvec;
+ }
+
+ if (drag)
+ arcade_velocity *= exp(-drag * seconds);
+
+ LinearFrame(seconds);
+
+ // move the position by the (time-frame scaled) velocity:
+ pos += arcade_velocity * seconds +
+ velocity * seconds;
+
+ cam.MoveTo(pos);
+
+ s -= seconds;
+ }
+
+ alpha = 0.0f;
+
+ // now update the graphic rep and light sources:
+ if (rep) {
+ rep->MoveTo(cam.Pos());
+ rep->SetOrientation(cam.Orientation());
+ }
+
+ if (light) {
+ light->MoveTo(cam.Pos());
+ }
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::AngularFrame(double seconds)
+{
+ if (!straight) {
+ dr += (float) (dr_acc * seconds);
+ dy += (float) (dy_acc * seconds);
+ dp += (float) (dp_acc * seconds);
+
+ dr *= (float) exp(-dr_drg * seconds);
+ dy *= (float) exp(-dy_drg * seconds);
+ dp *= (float) exp(-dp_drg * seconds);
+
+ roll = (float) (dr * seconds);
+ pitch = (float) (dp * seconds);
+ yaw = (float) (dy * seconds);
+
+ if (shake > 0.01) {
+ vibration = Point(random(), random(), random());
+ vibration.Normalize();
+ vibration *= (float) (shake * seconds);
+
+ shake *= (float) exp(-1.5 * seconds);
+ }
+ else {
+ vibration.x = vibration.y = vibration.z = 0.0f;
+ shake = 0.0f;
+ }
+
+ cam.Aim(roll, pitch, yaw);
+ }
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::LinearFrame(double seconds)
+{
+ // deal with lateral thrusters:
+
+ if (trans_x) { // side-to-side
+ Point transvec = cam.vrt();
+ transvec *= ((trans_x/mass) * seconds);
+
+ velocity += transvec;
+ }
+
+ if (trans_y) { // fore-and-aft
+ Point transvec = cam.vpn();
+ transvec *= ((trans_y/mass) * seconds);
+
+ velocity += transvec;
+ }
+
+ if (trans_z) { // up-and-down
+ Point transvec = cam.vup();
+ transvec *= ((trans_z/mass) * seconds);
+
+ velocity += transvec;
+ }
+
+ // if gravity applies, attract:
+ if (primary_mass > 0) {
+ Point g = primary_loc - cam.Pos();
+ double r = g.Normalize();
+
+ g *= GRAV * primary_mass / (r*r);
+
+ velocity += g * seconds;
+ }
+
+ // constant gravity:
+ else if (g_accel > 0) {
+ velocity += Point(0, -g_accel, 0) * seconds;
+ }
+
+ // if drag applies, decellerate:
+ if (drag)
+ velocity *= exp(-drag * seconds);
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::CalcFlightPath()
+{
+ flight_path_yaw = 0.0f;
+ flight_path_pitch = 0.0f;
+
+ // transform flight path into camera frame:
+ Point flight_path = velocity;
+ if (flight_path.Normalize() < 1)
+ return;
+
+ Point tmp = flight_path;
+ flight_path.x = tmp * cam.vrt();
+ flight_path.y = tmp * cam.vup();
+ flight_path.z = tmp * cam.vpn();
+
+ if (flight_path.z < 0.1)
+ return;
+
+ // first, compute azimuth:
+ flight_path_yaw = (float) atan(flight_path.x / flight_path.z);
+ if (flight_path.z < 0) flight_path_yaw -= (float) PI;
+ if (flight_path_yaw < -PI) flight_path_yaw += (float) (2*PI);
+
+ // then, rotate path into azimuth frame to compute elevation:
+ Camera yaw_cam;
+ yaw_cam.Clone(cam);
+ yaw_cam.Yaw(flight_path_yaw);
+
+ flight_path.x = tmp * yaw_cam.vrt();
+ flight_path.y = tmp * yaw_cam.vup();
+ flight_path.z = tmp * yaw_cam.vpn();
+
+ flight_path_pitch = (float) atan(flight_path.y / flight_path.z);
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::MoveTo(const Point& new_loc)
+{
+ cam.MoveTo(new_loc);
+}
+
+void
+Physical::TranslateBy(const Point& ref)
+{
+ Point new_loc = cam.Pos() - ref;
+ cam.MoveTo(new_loc);
+}
+
+void
+Physical::ApplyForce(const Point& force)
+{
+ velocity += force/mass;
+}
+
+void
+Physical::ApplyTorque(const Point& torque)
+{
+ dr += (float) (torque.x/mass);
+ dp += (float) (torque.y/mass);
+ dy += (float) (torque.z/mass);
+}
+
+void
+Physical::SetThrust(double t)
+{
+ thrust = (float) t;
+}
+
+void
+Physical::SetTransX(double t)
+{
+ trans_x = (float) t;
+}
+
+void
+Physical::SetTransY(double t)
+{
+ trans_y = (float) t;
+}
+
+void
+Physical::SetTransZ(double t)
+{
+ trans_z = (float) t;
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::SetHeading(double r, double p, double y)
+{
+ roll = (float) r;
+ pitch = (float) p;
+ yaw = (float) y;
+
+ cam.Aim(roll, pitch, yaw);
+}
+
+void
+Physical::LookAt(const Point& dst)
+{
+ cam.LookAt(dst);
+}
+
+void
+Physical::CloneCam(const Camera& c)
+{
+ cam.Clone(c);
+}
+
+void
+Physical::SetAbsoluteOrientation(double r, double p, double y)
+{
+ roll = (float) r;
+ pitch = (float) p;
+ yaw = (float) y;
+
+ Camera work(Location().x, Location().y, Location().z);
+ work.Aim(r,p,y);
+ cam.Clone(work);
+}
+
+void
+Physical::ApplyRoll(double r)
+{
+ if (r > 1) r = 1;
+ else if (r < -1) r = -1;
+
+ dr_acc = (float) r * roll_rate;
+}
+
+void
+Physical::ApplyPitch(double p)
+{
+ if (p > 1) p = 1;
+ else if (p < -1) p = -1;
+
+ dp_acc = (float) p * pitch_rate;
+}
+
+void
+Physical::ApplyYaw(double y)
+{
+ if (y > 1) y = 1;
+ else if (y < -1) y = -1;
+
+ dy_acc = (float) y * yaw_rate;
+}
+
+void
+Physical::SetAngularRates(double r, double p, double y)
+{
+ roll_rate = (float) r;
+ pitch_rate = (float) p;
+ yaw_rate = (float) y;
+}
+
+void
+Physical::GetAngularRates(double& r, double& p, double& y)
+{
+ r = roll_rate;
+ p = pitch_rate;
+ y = yaw_rate;
+}
+
+void
+Physical::SetAngularDrag(double r, double p, double y)
+{
+ dr_drg = (float) r;
+ dp_drg = (float) p;
+ dy_drg = (float) y;
+}
+
+void
+Physical::GetAngularDrag(double& r, double& p, double& y)
+{
+ r = dr_drg;
+ p = dp_drg;
+ y = dy_drg;
+}
+
+void
+Physical::GetAngularThrust(double& r, double& p, double& y)
+{
+ r = 0;
+ p = 0;
+ y = 0;
+
+ if (dr_acc > 0.05 * roll_rate) r = 1;
+ else if (dr_acc < -0.05 * roll_rate) r = -1;
+ else if (dr > 0.01 * roll_rate) r = -1;
+ else if (dr < -0.01 * roll_rate) r = 1;
+
+ if (dy_acc > 0.05 * yaw_rate) y = 1;
+ else if (dy_acc < -0.05 * yaw_rate) y = -1;
+ else if (dy > 0.01 * yaw_rate) y = -1;
+ else if (dy < -0.01 * yaw_rate) y = 1;
+
+ if (dp_acc > 0.05 * pitch_rate) p = 1;
+ else if (dp_acc < -0.05 * pitch_rate) p = -1;
+ else if (dp > 0.01 * pitch_rate) p = -1;
+ else if (dp < -0.01 * pitch_rate) p = 1;
+}
+
+
+void
+Physical::SetPrimary(const Point& l, double m)
+{
+ primary_loc = l;
+ primary_mass = m;
+}
+
+void
+Physical::SetGravity(double g)
+{
+ if (g >= 0)
+ g_accel = (float) g;
+}
+
+void
+Physical::SetBaseDensity(double d)
+{
+ if (d >= 0)
+ Do = (float) d;
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::InflictDamage(double damage, int /*type*/)
+{
+ integrity -= (float) damage;
+
+ if (integrity < 1.0f)
+ integrity = 0.0f;
+}
+
+// +--------------------------------------------------------------------+
+
+int
+Physical::CollidesWith(Physical& o)
+{
+ // representation collision test (will do bounding spheres first):
+ if (rep && o.rep)
+ return rep->CollidesWith(*o.rep);
+
+ Point delta_loc = Location() - o.Location();
+
+ // bounding spheres test:
+ if (delta_loc.length() > radius + o.radius)
+ return 0;
+
+ // assume collision:
+ return 1;
+}
+
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::ElasticCollision(Physical& a, Physical& b)
+{
+ double mass_sum = a.mass + b.mass;
+ double mass_delta = a.mass - b.mass;
+
+ Point vel_a = (Point(b.velocity) * (2 * b.mass) + Point(a.velocity) * mass_delta) * (1/mass_sum);
+ Point vel_b = (Point(a.velocity) * (2 * a.mass) - Point(b.velocity) * mass_delta) * (1/mass_sum);
+
+ a.velocity = vel_a;
+ b.velocity = vel_b;
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::InelasticCollision(Physical& a, Physical& b)
+{
+ double mass_sum = a.mass + b.mass;
+
+ Point vel_a = (Point(a.velocity) * a.mass + Point(b.velocity) * b.mass) * (1/mass_sum);
+
+ a.velocity = vel_a;
+ b.velocity = vel_a;
+}
+
+// +--------------------------------------------------------------------+
+
+void
+Physical::SemiElasticCollision(Physical& a, Physical& b)
+{
+ double mass_sum = a.mass + b.mass;
+ double mass_delta = a.mass - b.mass;
+
+ Point avel = a.Velocity();
+ Point bvel = b.Velocity();
+ Point dv = avel - bvel;
+
+ // low delta-v: stick
+ if (dv.length() < 20) {
+ if (a.mass > b.mass) {
+ b.velocity = a.velocity;
+ }
+
+ else {
+ a.velocity = b.velocity;
+ }
+ }
+
+ // high delta-v: bounce
+ else {
+ Point Ve_a = (bvel * (2 * b.mass) + avel * mass_delta) * (1/mass_sum) * 0.65;
+ Point Ve_b = (avel * (2 * a.mass) - bvel * mass_delta) * (1/mass_sum) * 0.65;
+ Point Vi_ab = (avel * a.mass + bvel * b.mass) * (1/mass_sum) * 0.35;
+
+ a.arcade_velocity = Point();
+ b.arcade_velocity = Point();
+
+ a.velocity = Ve_a + Vi_ab;
+ b.velocity = Ve_b + Vi_ab;
+ }
+}
+
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