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Advanced Ballistics - Utilize vector library
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@ulteq
ulteq committed Oct 29, 2017
1 parent 4f78062 commit 3d1e9db
Showing 1 changed file with 63 additions and 104 deletions.
167 changes: 63 additions & 104 deletions extensions/advanced_ballistics/AdvancedBallistics.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@
#include <cmath>
#include <sstream>

#include "vector.hpp"

#define DT_ZERO 0.02
#define DT_SIMULATION 0.005
#define GRAVITY 9.8066f
Expand Down Expand Up @@ -40,8 +42,8 @@ struct Bullet {
double stabilityFactor;
double twistDirection;
double transonicStabilityCoef;
std::vector<double> bulletVelocity;
std::vector<double> origin;
ace::vector3<double> bulletVelocityPreviousFrame;
ace::vector3<double> origin;
double latitude;
double temperature;
double altitude;
Expand Down Expand Up @@ -408,8 +410,8 @@ void __stdcall RVExtension(char *output, int outputSize, const char *function)
bulletDatabase[index].stabilityFactor = stabilityFactor;
bulletDatabase[index].twistDirection = twistDirection;
bulletDatabase[index].transonicStabilityCoef = transonicStabilityCoef;
bulletDatabase[index].bulletVelocity = bulletVelocity;
bulletDatabase[index].origin = origin;
bulletDatabase[index].bulletVelocityPreviousFrame = { bulletVelocity[0], bulletVelocity[1], bulletVelocity[2] };
bulletDatabase[index].origin = { origin[0], origin[1], origin[2] };
bulletDatabase[index].latitude = latitude / 180 * M_PI;
bulletDatabase[index].temperature = temperature;
bulletDatabase[index].altitude = altitude;
Expand Down Expand Up @@ -460,186 +462,143 @@ void __stdcall RVExtension(char *output, int outputSize, const char *function)
heightAGL = strtod(strtok_s(NULL, ":", &next_token), NULL);
tickTime = strtod(strtok_s(NULL, ":", &next_token), NULL);

ace::vector3<double> bulletVelocityCurrentFrame = { velocity[0], velocity[1], velocity[2] };
ace::vector3<double> bulletPosition = { position[0], position[1], position[2] };
ace::vector3<double> windVelocity = { wind[0], wind[1], wind[2] };
ace::vector3<double> gravityAccel = { 0, 0, -GRAVITY };
double ballisticCoefficient = 1.0;
double dragRef = 0.0;
double drag = 0.0;
double accelRef[3] = { 0.0, 0.0, 0.0 };
double accel[3] = { 0.0, 0.0, 0.0 };
ace::vector3<double> accelRef;
ace::vector3<double> accel;
double TOF = tickTime - bulletDatabase[index].startTime;
double deltaT = tickTime - bulletDatabase[index].lastFrame;
double trueVelocity[3] = { 0.0, 0.0, 0.0 };
double trueSpeed = 0.0;
double temperature = bulletDatabase[index].temperature - 0.0065 * position[2];
double pressure = (1013.25 - 10 * bulletDatabase[index].overcast) * pow(1 - (0.0065 * (bulletDatabase[index].altitude + position[2])) / (KELVIN(temperature) + 0.0065 * bulletDatabase[index].altitude), 5.255754495);
ace::vector3<double> trueVelocity;
double temperature = bulletDatabase[index].temperature - 0.0065 * bulletPosition.z();
double pressure = (1013.25 - 10 * bulletDatabase[index].overcast) * pow(1 - (0.0065 * (bulletDatabase[index].altitude + bulletPosition.z())) / (KELVIN(temperature) + 0.0065 * bulletDatabase[index].altitude), 5.255754495);
double windSpeed = 0.0;
double windAttenuation = 1.0;
double velocityOffset[3] = { 0.0, 0.0, 0.0 };
ace::vector3<double> velocityOffset;

bulletDatabase[index].lastFrame = tickTime;

windSpeed = sqrt(pow(wind[0], 2) + pow(wind[1], 2) + pow(wind[2], 2));
if (windSpeed > 0.1) {
double windSourceTerrain[3];
if (windVelocity.magnitude() > 0.1) {
double windAttenuation = 1.0;
ace::vector3<double> windSourceTerrain;

windSourceTerrain[0] = position[0] - wind[0] / windSpeed * 100;
windSourceTerrain[1] = position[1] - wind[1] / windSpeed * 100;
windSourceTerrain[2] = position[2] - wind[2] / windSpeed * 100;
windSourceTerrain = bulletPosition - windVelocity.normalize() * 100;

int gridX = (int)floor(windSourceTerrain[0] / 50);
int gridY = (int)floor(windSourceTerrain[1] / 50);
int gridX = (int)floor(windSourceTerrain.x() / 50);
int gridY = (int)floor(windSourceTerrain.y() / 50);
int gridCell = gridX * map->mapGrids + gridY;

if (gridCell >= 0 && (std::size_t)gridCell < map->gridHeights.size() && (std::size_t)gridCell < map->gridBuildingNums.size()) {
double gridHeight = map->gridHeights[gridCell];

if (gridHeight > position[2]) {
double angle = atan((gridHeight - position[2]) / 100);
if (gridHeight > bulletPosition.z()) {
double angle = atan((gridHeight - bulletPosition.z()) / 100);
windAttenuation *= pow(abs(cos(angle)), 2);
}
}
}

if (windSpeed > 0.1) {
double windSourceObstacles[3];
if (heightAGL > 0 && heightAGL < 20) {
ace::vector3<double> windSourceObstacles;

windSourceObstacles[0] = position[0] - wind[0] / windSpeed * 25;
windSourceObstacles[1] = position[1] - wind[1] / windSpeed * 25;
windSourceObstacles[2] = position[2] - wind[2] / windSpeed * 25;
windSourceObstacles = bulletPosition - windVelocity.normalize() * 25;

if (heightAGL > 0 && heightAGL < 20) {
double roughnessLength = calculateRoughnessLength(windSourceObstacles[0], windSourceObstacles[1]);
double roughnessLength = calculateRoughnessLength(windSourceObstacles.x(), windSourceObstacles.y());
windAttenuation *= abs(log(heightAGL / roughnessLength) / log(20 / roughnessLength));
}
}

if (windAttenuation < 1) {
wind[0] *= windAttenuation;
wind[1] *= windAttenuation;
wind[2] *= windAttenuation;
windSpeed = sqrt(pow(wind[0], 2) + pow(wind[1], 2) + pow(wind[2], 2));
windVelocity = windVelocity * windAttenuation;
}

std::vector<double> bulletVelocity = bulletDatabase[index].bulletVelocity;
ace::vector3<double> bulletVelocity = bulletDatabase[index].bulletVelocityPreviousFrame;
double time = 0.0;

while (time < deltaT) {
double dt = std::min(deltaT - time, DT_SIMULATION);

double bulletSpeed = sqrt(pow(bulletVelocity[0], 2) + pow(bulletVelocity[1], 2) + pow(bulletVelocity[2], 2));

dragRef = -bulletDatabase[index].airFriction * bulletSpeed * bulletSpeed;

accelRef[0] = (bulletVelocity[0] / bulletSpeed) * dragRef;
accelRef[1] = (bulletVelocity[1] / bulletSpeed) * dragRef;
accelRef[2] = (bulletVelocity[2] / bulletSpeed) * dragRef;
dragRef = -bulletDatabase[index].airFriction * bulletVelocity.magnitude_squared();

velocityOffset[0] += accelRef[0] * dt;
velocityOffset[1] += accelRef[1] * dt;
velocityOffset[2] += accelRef[2] * dt;
accelRef = bulletVelocity.normalize() * dragRef;

bulletVelocity[0] -= accelRef[0] * dt;
bulletVelocity[1] -= accelRef[1] * dt;
bulletVelocity[2] -= accelRef[2] * dt + GRAVITY * dt;
velocityOffset += accelRef * dt;
bulletVelocity -= accelRef * dt;
bulletVelocity += gravityAccel * dt;

time += dt;
}

bulletVelocity = bulletDatabase[index].bulletVelocity;
bulletVelocity = bulletDatabase[index].bulletVelocityPreviousFrame;
time = 0.0;
TOF -= deltaT;

while (time < deltaT) {
double dt = std::min(deltaT - time, DT_SIMULATION * 2);

trueVelocity[0] = bulletVelocity[0] - wind[0];
trueVelocity[1] = bulletVelocity[1] - wind[1];
trueVelocity[2] = bulletVelocity[2] - wind[2];
trueSpeed = sqrt(pow(trueVelocity[0], 2) + pow(trueVelocity[1], 2) + pow(trueVelocity[2], 2));
trueVelocity = bulletVelocity - windVelocity;

if (bulletDatabase[index].transonicStabilityCoef < 1.0f && trueSpeed < 1.2 * SPEED_OF_SOUND(temperature) && trueSpeed > SPEED_OF_SOUND(temperature)) {
if (bulletDatabase[index].transonicStabilityCoef < 1.0f && trueVelocity.magnitude() < 1.2 * SPEED_OF_SOUND(temperature) && trueVelocity.magnitude() > SPEED_OF_SOUND(temperature)) {
std::uniform_real_distribution<double> distribution(-10.0, 10.0);
ace::vector3<double> offset(distribution(bulletDatabase[index].randGenerator), distribution(bulletDatabase[index].randGenerator), distribution(bulletDatabase[index].randGenerator));
double coef = 1.0f - bulletDatabase[index].transonicStabilityCoef;

trueVelocity[0] += distribution(bulletDatabase[index].randGenerator) * coef;
trueVelocity[1] += distribution(bulletDatabase[index].randGenerator) * coef;
trueVelocity[2] += distribution(bulletDatabase[index].randGenerator) * coef;

double speed = sqrt(pow(trueVelocity[0], 2) + pow(trueVelocity[1], 2) + pow(trueVelocity[2], 2));

trueVelocity[0] *= trueSpeed / speed;
trueVelocity[1] *= trueSpeed / speed;
trueVelocity[2] *= trueSpeed / speed;
double trueSpeed = trueVelocity.magnitude();
trueVelocity += offset * coef;
trueVelocity = trueVelocity.normalize() * trueSpeed;
};

if (bulletDatabase[index].ballisticCoefficients.size() == bulletDatabase[index].velocityBoundaries.size() + 1) {
ballisticCoefficient = bulletDatabase[index].ballisticCoefficients[0];
for (int i = (int)bulletDatabase[index].velocityBoundaries.size() - 1; i >= 0; i = i - 1) {
if (trueSpeed < bulletDatabase[index].velocityBoundaries[i]) {
if (trueVelocity.magnitude() < bulletDatabase[index].velocityBoundaries[i]) {
ballisticCoefficient = bulletDatabase[index].ballisticCoefficients[i + 1];
break;
}
}

ballisticCoefficient = calculateAtmosphericCorrection(ballisticCoefficient, temperature, pressure, bulletDatabase[index].humidity, bulletDatabase[index].atmosphereModel);

drag = calculateRetard(bulletDatabase[index].dragModel, ballisticCoefficient, trueSpeed, SPEED_OF_SOUND(temperature));
}
else {
drag = calculateRetard(bulletDatabase[index].dragModel, ballisticCoefficient, trueVelocity.magnitude(), SPEED_OF_SOUND(temperature));
} else {
double airDensity = calculateAirDensity(temperature, pressure, bulletDatabase[index].humidity);
double airFriction = bulletDatabase[index].airFriction * airDensity / STD_AIR_DENSITY_ICAO;

drag = -airFriction * trueSpeed * trueSpeed;
drag = -airFriction * trueVelocity.magnitude_squared();
}

accel[0] = (trueVelocity[0] / trueSpeed) * drag;
accel[1] = (trueVelocity[1] / trueSpeed) * drag;
accel[2] = (trueVelocity[2] / trueSpeed) * drag;

velocityOffset[0] -= accel[0] * dt;
velocityOffset[1] -= accel[1] * dt;
velocityOffset[2] -= accel[2] * dt;
accel = trueVelocity.normalize() * drag;

bulletVelocity[0] -= accel[0] * dt;
bulletVelocity[1] -= accel[1] * dt;
bulletVelocity[2] -= accel[2] * dt;
velocityOffset -= accel * dt;
bulletVelocity -= accel * dt;

if (TOF > 0) {
double bulletDir = atan2(bulletVelocity[0], bulletVelocity[1]);
double bulletDir = atan2(bulletVelocity.x(), bulletVelocity.y());
double driftAccel = bulletDatabase[index].twistDirection * (0.0482251 * (bulletDatabase[index].stabilityFactor + 1.2)) / pow(TOF, 0.17);
double driftVelocity = 0.0581025 *(bulletDatabase[index].stabilityFactor + 1.2) * pow(TOF, 0.83);
double dragCorrection = (driftVelocity / trueSpeed) * drag;
double velocityOffsetX = sin(bulletDir + M_PI / 2) * (driftAccel + dragCorrection) * dt;
double velocityOffsetY = cos(bulletDir + M_PI / 2) * (driftAccel + dragCorrection) * dt;

velocityOffset[0] += velocityOffsetX;
velocityOffset[1] += velocityOffsetY;

bulletVelocity[0] += velocityOffsetX;
bulletVelocity[1] += velocityOffsetY;
double dragCorrection = (driftVelocity / trueVelocity.magnitude()) * drag;
double magnitude = (driftAccel + dragCorrection) * dt;
ace::vector3<double> offset(sin(bulletDir + M_PI / 2) * magnitude, cos(bulletDir + M_PI / 2) * magnitude, 0);
velocityOffset += offset;
bulletVelocity += offset;
}

double lat = bulletDatabase[index].latitude;
accel[0] = 2 * EARTH_ANGULAR_SPEED * +(bulletVelocity[1] * sin(lat) - bulletVelocity[2] * cos(lat));
accel[1] = 2 * EARTH_ANGULAR_SPEED * -(bulletVelocity[0] * sin(lat));
accel[2] = 2 * EARTH_ANGULAR_SPEED * +(bulletVelocity[0] * cos(lat));

velocityOffset[0] += accel[0] * dt;
velocityOffset[1] += accel[1] * dt;
velocityOffset[2] += accel[2] * dt;
ace::vector3<double> accel;
accel.x(2 * EARTH_ANGULAR_SPEED * +(bulletVelocity.y() * sin(lat) - bulletVelocity.z() * cos(lat)));
accel.y(2 * EARTH_ANGULAR_SPEED * -(bulletVelocity.x() * sin(lat)));
accel.z(2 * EARTH_ANGULAR_SPEED * +(bulletVelocity.x() * cos(lat)));

bulletVelocity[0] += accel[0] * dt;
bulletVelocity[1] += accel[1] * dt;
bulletVelocity[2] += accel[2] * dt - GRAVITY * dt;
velocityOffset += accel * dt;
bulletVelocity += accel * dt + gravityAccel * dt;

TOF += dt;
time += dt;
}

bulletDatabase[index].bulletVelocity[0] = velocity[0] + velocityOffset[0];
bulletDatabase[index].bulletVelocity[1] = velocity[1] + velocityOffset[1];
bulletDatabase[index].bulletVelocity[2] = velocity[2] + velocityOffset[2];
bulletDatabase[index].bulletVelocityPreviousFrame = bulletVelocityCurrentFrame + velocityOffset;

outputStr << "[" << velocityOffset[0] << "," << velocityOffset[1] << "," << velocityOffset[2] << "]";
outputStr << "[" << velocityOffset.x() << "," << velocityOffset.y() << "," << velocityOffset.z() << "]";
strncpy_s(output, outputSize, outputStr.str().c_str(), _TRUNCATE);
EXTENSION_RETURN();
} else if (!strcmp(mode, "set")) {
Expand Down

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