cuda编程学习5——波纹ripple

/共有ＤＩＭ×ＤＩＭ个像素，每个像素对应一个线程
dim3 blocks(DIM/16,DIM/16);//2维
dim3 threads(16,16);//2维
kernel<<<blocks,threads>>>(d->dev_bitmap,ticks);

代码：

/*
============================================================================
Name : ripple.cu
Author : can
Version :
Copyright : Your copyright notice
Description : CUDA compute reciprocals
============================================================================
*/

#include <iostream>
#include <math.h>
#include"cpu_anim.h"
using namespace std;

static void CheckCudaErrorAux (const char *, unsigned, const char *, cudaError_t);
#define CUDA_CHECK_RETURN(value) CheckCudaErrorAux(__FILE__,__LINE__, #value, value)
#define DIM 160

struct DataBlock
{
unsigned char *dev_bitmap;
CPUAnimBitmap *bitmap;
};
void cleanup(DataBlock *d)
{
cudaFree(d->dev_bitmap);
}
void generate_frame(DataBlock *d,int ticks);
__global__ void kernel(unsigned char *ptr,int ticks)
{
//将threadId和blockId映射到像素位置
int x=threadIdx.x+blockIdx.x*blockDim.x;
int y=threadIdx.y+blockIdx.y*blockDim.y;
int offset=x+y*blockDim.x*gridDim.x;
float fx=x-DIM/2;
float fy=y-DIM/2;
float d=sqrtf(fx*fx+fy*fy);
unsigned char grey=(unsigned char)(128.0f+127.0f*cos(d/10.0f-ticks/7.0f)/(d/10.0f+1.0f));
ptr[offset*4+0]=grey;
ptr[offset*4+1]=grey;
ptr[offset*4+2]=grey;
ptr[offset*4+3]=255;
}
int main()
{
DataBlock data;
CPUAnimBitmap bitmap(DIM,DIM,&data);
data.bitmap = &bitmap;
CUDA_CHECK_RETURN(cudaMalloc((void **)&data.dev_bitmap,bitmap.image_size()));
bitmap.anim_and_exit((void (*)(void*,int))generate_frame,(void (*)(void*))cleanup);
}
void generate_frame(DataBlock *d,int ticks)
{
//共有ＤＩＭ×ＤＩＭ个像素，每个像素对应一个线程
dim3 blocks(DIM/16,DIM/16);//2维
dim3 threads(16,16);//2维
kernel<<<blocks,threads>>>(d->dev_bitmap,ticks);
CUDA_CHECK_RETURN(cudaMemcpy(d->bitmap->get_ptr(),d->dev_bitmap,d->bitmap->image_size(),cudaMemcpyDeviceToHost));
}
static void CheckCudaErrorAux (const char *file, unsigned line, const char *statement, cudaError_t err)
{
if (err == cudaSuccess)
return;
std::cerr << statement<<" returned " << cudaGetErrorString(err) << "("<<err<< ") at "<<file<<":"<<line << std::endl;
exit (1);
}