I'm using CUDA 4.1 to parse in the update of my Particle system that I've made with DirectX 10. So far, my update method for the particle systems is 1 line of code within a for loop that makes each particle fall down the y axis to simulate a waterfall:

m_particleList[i].positionY = m_particleList[i].positionY - (m_particleList[i].velocity * frameTime * 0.001f);

In my .cu class I've created a struct which I copied from my particle class and is as follows:

struct ParticleType
{
    float positionX, positionY, positionZ;
    float red, green, blue;
    float velocity;
    bool active;
};

Then I have an UpdateParticle method in the .cu as well. This encompass the 3 main parameters my particles need to update themselves based off the initial line of code. :

   __global__ void UpdateParticle(float* position, float* velocity, float frameTime)
{

}

This is my first CUDA program and I'm at a loss to what to do next. I've tried to simply put the particleList line in the UpdateParticle method, but then the particles don't fall down as they should.

I believe it is because I am not calling something that I need to in the class where the particle fall code use to be. Could someone please tell me what it is I am missing to get it working as it should?

If I am doing this completely wrong in general, the please inform me as well.