Prediction Algorithm?

[Joh]

Hi,

i did a prediction algorithm but it's not good enough for me, do you know some good prediction algorithm?

 

In my project the projectile is slower then a gunshoot, so i need to predict where it will be the target and where i should aim to hit it.

What i did is predicting good but is not so fast as i expected so did you have any good one?

 

Thx.

[Joh]

Never mind, found it.

 

distance_to_origin(P+t*V) = s*t

dot_product(P+t*V,P+t*V) = s^2*t^2

dot_product(P,P)+2*dot_product(P,V)*t+dot_product( V,V)*t^2 = s^2*t^2

dot_product(P,P)+2*dot_product(P,V)*t+(dot_product (V,V)-s^2)*t^2 = 0

[Chiblue]

Why would you not just do a raycast for the distance of the projectile and then calculate a projection curve to hit that point... if you don't hit a target just us a pivot entity to move to the range distance from your weapon... check the raycast to that point and plot a path to there?

 

Alternatively, You could simply create a projectile object, apply mass then apply a force in the relevant direction... so long as the mass and force are appropriate your projectile should travel accordingly using physics and gravity..

[Joh]

You misunderstood i should predict WHERE to hit.. It's for Ai agent, as projectile is not fast as a gun (you fire, and it will hit few millisecs later) i should predict where the target will be to be able to hit it.

[Sanctus]

Well you know a target moves. You know it's speed and direction. You know the distance to the target as well. Based on that distance you calculate the time needed for a bullet to get there (in millisecs). Knowing that time you calculate where the target will be by that time. Then just fire there.

[Joh]

mmm did i wrote incorrectly? In second post i said i found.

Anyway in the way you suggest the projectile won't be precise.. Just immagine the target is moving far to you on right.. You'll never hit in that way.

Anyway i found the solution (second post) should i write solved on title? How?

Sorry i am pretty new on this forum.

[Joh]

Anyway for who need it more clear here there is the whole code.

This code need to be converted on Leadwers.

 

#include <iostream>
#include <cmath>

typedef double Real;

struct Vector3D {
 Real x, y, z;
 Vector3D(Real x, Real y, Real z) : x(x), y(y), z(z) {
 }

};

std::ostream &operator<<(std::ostream &os, Vector3D const &v) {
 return os << '(' << v.x << ',' << v.y << ',' << v.z << ')';
}

Vector3D operator+(Vector3D const &v1, Vector3D const &v2) {
 return Vector3D(v1.x+v2.x, v1.y+v2.y, v1.z+v2.z);
}

Vector3D operator-(Vector3D const &v1, Vector3D const &v2) {
 return Vector3D(v1.x-v2.x, v1.y-v2.y, v1.z-v2.z);
}

Vector3D operator*(Real s, Vector3D const &v) {
 return Vector3D(s*v.x, s*v.y, s*v.z);
}

Real dot_product(Vector3D const &v1, Vector3D const &v2) {
 return v1.x*v2.x + v1.y*v2.y + v1.z*v2.z;
}

struct Point3D {
 Real x, y, z;
 Point3D(Real x, Real y, Real z) : x(x), y(y), z(z) {
 }
};

Vector3D operator-(Point3D const &p1, Point3D const &p2) {
 return Vector3D(p1.x-p2.x, p1.y-p2.y, p1.z-p2.z);
}

Real largest_root_of_second_degree_equation(double a, double b, double c) {
 return (-b+std::sqrt(b*b-4*a*c))/(2*a);
}

Vector3D shooting_direction(Point3D const &target_position,
		    Vector3D const &target_velocity,
		    Point3D const &shooter_position,
		    Vector3D const &shooter_velocity,
		    Real bullet_speed) {
 Vector3D P = target_position - shooter_position;
 Vector3D V = target_velocity - shooter_velocity;

 Real a = bullet_speed*bullet_speed - dot_product(V,V);
 Real b = -2*dot_product(P,V);
 Real c = -dot_product(P,P);

 Real t = largest_root_of_second_degree_equation(a,b,c);

 return target_position + t*V;
}

int main() {
 Point3D target(0,0,4);
 Vector3D target_velocity(3,0,0);
 Point3D O(0,0,0);
 Vector3D my_velocity(0,0,0);
 Real bullet_speed = 5;

 std::cout << shooting_direction(target,
			  target_velocity,
			  O,
			  my_velocity,
			  bullet_speed) << '\n';
}