OpenCL-无法修改值

Question

My Problem is, that I can't modify values in my kernel.

This is the code that does not work:

1st: the kernel:

__kernel void GetCellIndex(__global Particle* particles) {
    int globalID = get_global_id(0);
    particles[globalID].position.x = globalID;
};

2nd: the struct used in the kernel:

typedef struct _Particle
{
    float3 position;
}Particle;

3rd: the pushing from CPU to GPU:

(Particle*) particles = (Particle*)malloc(sizeof(Particle)*200);
for (int i = 0; i < 200; i++)
{
    particles[i].position.x = 5f;
}

cl_mem cl_Particles = clCreateBuffer(context, CL_MEM_READ_WRITE |
    CL_MEM_COPY_HOST_PTR, sizeof(Particle)*maxParticle, &particles[0], NULL);



//init of kernel etc.



err = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void *)&cl_Particles);
if (err != 0) {
    std::cout << "Error: setKernelArg 0 does not work!" << std::endl;
    system("Pause");
}

4th: run the kernel:

size_t localItem = 1;
err = clEnqueueNDRangeKernel(queue, kernel, 1, 0, &(size_t)200+1, &localItem, 0, NULL, NULL);
if (err != 0) {
    std::cout << "Error: EnqueueNDRange does not work!" << std::endl;
}

err = clFlush(queue);
if (err != 0) {
    std::cout << "Error: Flush does not work: " << err << std::endl;
}

err = clFinish(queue);
if (err != 0) {
    std::cout << "Error: Finish does not work: " << err << std::endl;
}

5th: the used struct on the GPU:

typedef struct _Particle
{
    cl_float3 position;
}Particle;

6th: finally the reading of the buffer:

clEnqueueReadBuffer(queue, cl_Particles, CL_TRUE, 0, 200 * sizeof(Particle), particles, 0, NULL, NULL);

after this steps my kernel does not effect the values returned in clEnqueueReadBuffer...

Does anyone know why? what is the problem here

Answer 1

Solved the problem:

Change the malloc line to something like

particles = new Particles[200];

also write the data in a seperate step to the buffer (with clEnqueueWriteBuffer(...) )

and the rest should work just like this code above