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https://github.com/acemod/ACE3.git
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075d1d6d9e
Gradually increase simulation step as the projectile approaches the target and improve the calculation of the final bullet drop. Untested. (#65)
123 lines
3.5 KiB
C++
123 lines
3.5 KiB
C++
/*
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* ace_fcs.cpp
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*
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* Calculates firing solution.
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*
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* Takes:
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* initSpeed,airFriction,angle,distance as string
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* Example: "900,-0.0004,2,1050"
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*
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* Returns:
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* Correction to angle
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*/
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#include "stdafx.h"
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#define _USE_MATH_DEFINES
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#include <math.h>
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#include <sstream>
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#include <vector>
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#include <string>
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#define MAXELEVATION 20
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#define MAXITERATIONS 120
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#define PRECISION 0.1
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#define RADIANS(X) (X / (180 / M_PI))
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static char version[] = "1.0";
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extern "C" {
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__declspec (dllexport) void __stdcall RVExtension(char *output, int outputSize, const char *function);
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};
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std::vector<std::string> splitString(std::string input) {
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std::istringstream ss(input);
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std::string token;
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std::vector<std::string> output;
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while (std::getline(ss, token, ',')) {
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output.push_back(token);
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}
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return output;
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}
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double traceBullet(double initSpeed, double airFriction, double angle, double angleTarget, double distance) {
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double velX, velY, posX, posY, lastPosX, lastPosY, posTargetX, posTargetY, velMag;
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velX = cos(RADIANS(angle)) * initSpeed;
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velY = sin(RADIANS(angle)) * initSpeed;
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posX = 0;
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posY = 0;
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posTargetX = cos(RADIANS(angleTarget)) * distance;
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posTargetY = sin(RADIANS(angleTarget)) * distance;
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double simulationStep = 0.05;
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int i = 0;
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while (i < MAXITERATIONS) {
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lastPosX = posX;
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lastPosY = posY;
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simulationStep = 0.1 - 0.049 * (posX / posTargetX);
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velMag = sqrt(pow(velX, 2) + pow(velY, 2));
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velX += simulationStep * (velX * velMag * airFriction);
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velY += simulationStep * (velY * velMag * airFriction - 9.81);
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posX += velX * simulationStep;
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posY += velY * simulationStep;
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if (posX >= posTargetX) { break; }
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i++;
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}
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double coef = (posTargetX - lastPosX) / (posX - lastPosX);
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return (lastPosY + (posY - lastPosY) * coef) - posTargetY;
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}
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double getSolution(double initSpeed, double airFriction, double angleTarget, double distance) {
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double posTargetX, posTargetY;
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posTargetX = cos(RADIANS(angleTarget)) * distance;
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posTargetY = sin(RADIANS(angleTarget)) * distance;
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if (traceBullet(initSpeed, airFriction, MAXELEVATION, angleTarget, distance) < 0) {
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return MAXELEVATION - angleTarget;
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}
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double a1 = angleTarget;
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double a2 = MAXELEVATION;
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double f1, f2, tmp;
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f1 = traceBullet(initSpeed, airFriction, a1, angleTarget, distance);
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if (fabs(f1) <= PRECISION) { return 0; }
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while (fabs(f1) > PRECISION) {
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f2 = traceBullet(initSpeed, airFriction, a2, angleTarget, distance);
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tmp = a2 - f2 * (a2 - a1) / (f2 - f1);
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a1 = a2;
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a2 = tmp;
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f1 = f2;
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}
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return a2 - angleTarget;
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}
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// i like to live dangerously. jk, fix strncpy sometime pls.
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#pragma warning( push )
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#pragma warning( disable : 4996 )
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void __stdcall RVExtension(char *output, int outputSize, const char *function) {
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if (!strcmp(function, "version")) {
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strncpy(output, version, outputSize);
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} else {
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std::vector<std::string> argStrings = splitString(function);
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double initSpeed = std::stod(argStrings[0]);
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double airFriction = std::stod(argStrings[1]);
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double angleTarget = std::stod(argStrings[2]);
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double distance = std::stod(argStrings[3]);
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double result = getSolution(initSpeed, airFriction, angleTarget, distance);
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std::string resultString = std::to_string(result);
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strcpy(output, resultString.c_str());
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output[outputSize - 1] = '\0';
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}
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}
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#pragma warning( pop )
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