I'm currently working on porting a particle system to update on the GPU via the use of CUDA. With CUDA, I've already passed over the required data I need to the GPU and allocated and copied the date via the host. When I build the project, it all runs fine, but when I run it, the project says I need to allocate my h_position pointer. This pointer is my host pointer and is meant to hold the data.

I know I need to pass in the current particle position to the required cudaMemcpy call and they are currently stored in a list with a for loop being created and interated for each particle calling the following line of code:

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

My current host side cuda code looks like this:

float* h_position; // Your host pointer. This holds the data (I assume it's already filled with the data.)
    float* d_position; // Your device pointer, we will allocate and fill this
    float* d_velocity;
    float* d_time;
    int threads_per_block = 128; // You should play with this value
    int blocks = m_maxParticles/threads_per_block + ( (m_maxParticles%threads_per_block)?1:0 );
    const int N = 10;
    size_t size = N * sizeof(float);
    cudaMalloc( (void**)&d_position, m_maxParticles * sizeof(float) );
    cudaMemcpy( d_position, h_position, m_maxParticles * sizeof(float), cudaMemcpyHostToDevice);

Both of which were / can be found inside my UpdateParticle() method. I had originally thought it would be a simple case of changing the h_position variable in the cudaMemcpy to m_particleList[i] but then I get the following error:

no suitable conversion function from "ParticleSystemClass::ParticleType" to "const void *" exists

I've probably messed up somewhere, but could someone please help fix the issues I'm facing. Everything else seems to running fine, it's just when I try to run the program that certain things hit the fan.