Displaying using VBO

Accelerated Computing CUDA CUDA Programming and Performance
1

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.

/*

 * Copyright 1993-2010 NVIDIA Corporation.  All rights reserved.

 *

 * Please refer to the NVIDIA end user license agreement (EULA) associated

 * with this source code for terms and conditions that govern your use of

 * this software. Any use, reproduction, disclosure, or distribution of

 * this software and related documentation outside the terms of the EULA

 * is strictly prohibited.

 *

 */

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

  * runtime API.

  * Device code.

  */

#ifndef _SIMPLEGL_KERNEL_H_

#define _SIMPLEGL_KERNEL_H_

///////////////////////////////////////////////////////////////////////////////

//! 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.

Regard,

Masterkiten

2

[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.