chapter4_4.cu

//#include <cuda_runtime.h>
#include <device_launch_parameters.h>
#include "cpu_bitmap.h"
#include "cu_complex_cuda.h"
#define DIM 500
__device__ int julia(int x, int y) {
	const float scale = 1.5;
	float jx = scale * (float)(DIM / 2 - x) / (DIM / 2);
	float jy = scale * (float)(DIM / 2 - y) / (DIM / 2);
	cuComplex c(-0.8, 0.156);
	cuComplex a(jx, jy);
	int i = 0;
	for (i = 0; i < 200; i++) {
		a = a * a + c;
		if (a.magnitude2() > 1000)
			return 0;
	}
	return 1;
}
__global__ void kernel(unsigned char* ptr) {
	int x = blockIdx.x;
	int y = blockIdx.y;
	int offset = x + y * gridDim.x;
	int juliaValue = julia(x, y);
	ptr[offset * 4 + 0] = 255 * juliaValue;
	ptr[offset * 4 + 1] = 0;
	ptr[offset * 4 + 2] = 0;
	ptr[offset * 4 + 3] = 255;
}
int main() {
	CPUBitmap bitmap(DIM, DIM);
	unsigned char* dev_bitmap;
	cudaMalloc((void**)&dev_bitmap, bitmap.image_size());
	dim3 grid(DIM, DIM);
	kernel<<<grid, 1>>>(dev_bitmap);
	cudaMemcpy(bitmap.get_ptr(), dev_bitmap, bitmap.image_size()
		, cudaMemcpyDeviceToHost);
	bitmap.display_and_exit();
	cudaFree(dev_bitmap);
}