MandelBrot set Using openCL - opencl

Question

Trying to use the same code (sort of) as what I have used when running using TBB (threading building blocks).
I don't have a great deal of experience with OpenCL, but I think most of the main code is correct. I believe the errors are in the .cl file, where it does the math.
Here is my mandelbrot code in TBB:
Mandelbrot TBB
Here is my code in OpenCL
Mandelbrot OpenCL
Any help would be greatly appreciated.

Answer 1

I changed the code in the kernel, and it ran fine. My new kernel code is the following:
// voronoi kernels
//
// local memory version
//
kernel void voronoiL(write_only image2d_t outputImage)
{
// get id of element in array
int x = get_global_id(0);
int y = get_global_id(1);
int w = get_global_size(0);
int h = get_global_size(1);
float4 result = (float4)(0.0f,0.0f,0.0f,1.0f);
float MinRe = -2.0f;
float MaxRe = 1.0f;
float MinIm = -1.5f;
float MaxIm = MinIm+(MaxRe-MinRe)*h/w;
float Re_factor = (MaxRe-MinRe)/(w-1);
float Im_factor = (MaxIm-MinIm)/(h-1);
float MaxIterations = 50;
//C imaginary
float c_im = MaxIm - y*Im_factor;
//C real
float c_re = MinRe + x*Re_factor;
//Z real
float Z_re = c_re, Z_im = c_im;
bool isInside = true;
bool col2 = false;
bool col3 = false;
int iteration =0;
for(int n=0; n<MaxIterations; n++)
{
// Z - real and imaginary
float Z_re2 = Z_re*Z_re, Z_im2 = Z_im*Z_im;
//if Z real squared plus Z imaginary squared is greater than c squared
if(Z_re2 + Z_im2 > 4)
{
if(n >= 0 && n <= (MaxIterations/2-1))
{
col2 = true;
isInside = false;
break;
}
else if(n >= MaxIterations/2 && n <= MaxIterations-1)
{
col3 = true;
isInside = false;
break;
}
}
Z_im = 2*Z_re*Z_im + c_im;
Z_re = Z_re2 - Z_im2 + c_re;
iteration++;
}
if(col2)
{
result = (float4)(iteration*0.05f,0.0f, 0.0f, 1.0f);
}
else if(col3)
{
result = (float4)(255, iteration*0.05f, iteration*0.05f, 1.0f);
}
else if(isInside)
{
result = (float4)(0.0f, 0.0f, 0.0f, 1.0f);
}
write_imagef(outputImage, (int2)(x, y), result);
}
You can also find it here:
https://docs.google.com/file/d/0B6DBARvnB__iUjNSTWJubFhUSDA/edit

Answer 2

See this link. It's developed by #eric-bainville. The CPU code both native and with OpenCL is not optimal (it does not use SSE/AVX) but I think the GPU code may be good. For the CPU you can speed up the code quite a bit by using AVX and operating on eight pixels at once.
http://www.bealto.com/mp-mandelbrot.html