Displaying using VBO

Hi I have something that I cannot understand how it works that much. So SDK called SimpleGL somehow uses extern “C” to wrap kernel

function to compile in C style but Im not sure how they can use values in host directly when calling kernel function. Bellow is the code.


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/* This example demonstrates how to use the Cuda OpenGL bindings with the

  * runtime API.

  * Device code.





//! Simple kernel to modify vertex positions in sine wave pattern

//! @param data  data in global memory


__global__ void kernel(float4* pos, unsigned int width, unsigned int height, float time)


    unsigned int x = blockIdx.x*blockDim.x + threadIdx.x;

    unsigned int y = blockIdx.y*blockDim.y + threadIdx.y;

// calculate uv coordinates

    float u = x / (float) width;

    float v = y / (float) height;

    u = u*2.0f - 1.0f;

    v = v*2.0f - 1.0f;

// calculate simple sine wave pattern

    float freq = 4.0f;

    float w = sinf(u*freq + time) * cosf(v*freq + time) * 0.5f;

// write output vertex

    pos[y*width+x] = make_float4(u, w, v, 1.0f);


// Wrapper for the __global__ call that sets up the kernel call

extern "C" void launch_kernel(float4* pos, unsigned int mesh_width, unsigned int mesh_height, float time)


    // execute the kernel

    dim3 block(8, 8, 1);

    dim3 grid(mesh_width / block.x, mesh_height / block.y, 1);

    kernel<<< grid, block>>>(pos, mesh_width, mesh_height, time);


#endif // #ifndef _SIMPLEGL_KERNEL_H_

does anybody know how this works? Is there case when I can directly use host memory instead of sending values to GPU using

cudaMemcpy and cudaMalloc? Thank you.



[font=“Courier New”]launch_kernel()[/font] is called with a device pointer as first argument. Declaring it as C linking style doesn’t prevent that.