Making particles accelerate toward a mouse point

Question

I'm currently working on a particle simulation program that makes pixels move towards a mouse point continually accelerating, but i'm running into some math issues. Currently my particle will accelerate in the direction of the mouse point, but will not actually accelerate towards a given point(only in it's direction).

To get an idea of what I'm trying to accomplish, my older program does just this but uses the fixed function pipeline. I want to recreate this program using the programmable pipeline and as a result changed around a lot of the program, there is really no similar code between the two at this point. Example of my problem:

As you can see the particle only accelerate in the direction of the cursor, my main equation I'm using is:

//if left mouse button is pressed
if(sf::Mouse::isButtonPressed(sf::Mouse::Left)){
        p.speed += glm::vec3(-pos.x * 30, -pos.y * 30 ,0.0f);   //increase speed in direction
}
//update position of particle with a little bit of spread -- speed(dt) * DRAG * Rand
p.pos += p.speed * (float)(delta) * DRAG * glm::vec3(rand()%5,rand()%5,0);

where my particle struct is:

struct Particle{
    glm::vec3 pos, speed;       //position, speed
    unsigned char r,g,b,a;      //color
    float size, angle, weight;  //?
    float life;                 //remaining life of a particle, if <0 it's super dead
    float cameradistance;       //squared distance to camera : -1.0f if dead

    //used for std::sort, needs an overloaded comparison operator
    bool operator<(const Particle& that) const {
        return this->cameradistance > that.cameradistance;
    }
};

how would I go about simulating the behavior of my first program with this second program I'm writing? I can't seem to wrap my head around doing this as the program structure is so drastically different.

Answer 1

Well if I understand well as @user8363 explained in the comments, your problem is that you are making one direction for all the particles, which makes the particles move in that direction. If you want the particles to accelerate toward the point you need to make a direction vector for each particle. For instance:

foreach particle:
    acc = particle - mousePosition; // assuming mousePosition is actually a vec3.

Then updated each particle accordingly.