Sorry I do not use OpenCL nor C# but You can do this fully inside shaders using GLSL (but you might have precision problems as for Julia like fractals is sometimes even 64bit double not enough). Anyway here a simple example of Mandelbrot set I did some years back...
CPU side app C++/OpenGL/GLSL/VCL code::
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "Unit1.h" // VCL window header
#include "gl\\OpenGL3D_double.cpp" // my GL engine
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
OpenGLscreen scr;
GLSLprogram shd;
float mx=0.0,my=0.0,mx0=0.0,my0=0.0,mx1=0.0,my1=0.0;
TShiftState sh0,sh1;
int xs=1,ys=1;
int txrmap=-1;
float zoom=1.000;
unsigned int queryID[2];
//---------------------------------------------------------------------------
void gl_draw()
{
float x,y,dx,dy;
scr.cls();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// matrix for old GL rendering
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
// GLSL uniforms
shd.bind();
shd.set1i("txrmap",0); // texture unit
shd.set2f("p0",mx,my); // pan position
shd.set1f("zoom",zoom); // zoom
// issue the first query
// Records the time only after all previous
// commands have been completed
glQueryCounter(queryID[0], GL_TIMESTAMP);
// QUAD covering screen
scr.txrs.bind(txrmap);
glColor3f(1.0,1.0,1.0);
glBegin(GL_QUADS);
glTexCoord2f(0.0,0.0); glVertex2f(-1.0,+1.0);
glTexCoord2f(0.0,1.0); glVertex2f(-1.0,-1.0);
glTexCoord2f(1.0,1.0); glVertex2f(+1.0,-1.0);
glTexCoord2f(1.0,0.0); glVertex2f(+1.0,+1.0);
glEnd();
shd.unbind();
scr.txrs.unbind();
// issue the second query
// records the time when the sequence of OpenGL
// commands has been fully executed
glQueryCounter(queryID[1], GL_TIMESTAMP);
// GL driver info and GLSL log
scr.text_init_pix(1.0);
glColor4f(0.0,0.2,1.0,0.8);
scr.text(glGetAnsiString(GL_VENDOR));
scr.text(glGetAnsiString(GL_RENDERER));
scr.text("OpenGL ver: "+glGetAnsiString(GL_VERSION));
glColor4f(0.4,0.7,0.8,0.8);
for (int i=1;i<=shd.log.Length();) scr.text(str_load_lin(shd.log,i,true));
scr.text_exit();
scr.exe();
scr.rfs();
// wait until the results are available
int e;
unsigned __int64 t0,t1;
for (e=0;!e;) glGetQueryObjectiv(queryID[0],GL_QUERY_RESULT_AVAILABLE,&e);
for (e=0;!e;) glGetQueryObjectiv(queryID[1],GL_QUERY_RESULT_AVAILABLE,&e);
glGetQueryObjectui64v(queryID[0], GL_QUERY_RESULT, &t0);
glGetQueryObjectui64v(queryID[1], GL_QUERY_RESULT, &t1);
Form1->Caption=AnsiString().sprintf("Time spent on the GPU: %f ms\n", (t1-t0)/1000000.0);
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner):TForm(Owner)
{
scr.init(this);
OpenGLtexture txr;
txr.load ("gradient.jpg");
txrmap=scr.txrs.add(txr);
shd.set_source_file("","","","Mandelbrot_set.glsl_vert","Mandelbrot_set.glsl_frag");
glGenQueries(2, queryID);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
scr.exit();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormResize(TObject *Sender)
{
scr.resize();
xs=ClientWidth;
ys=ClientHeight;
gl_draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormPaint(TObject *Sender)
{
gl_draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseMove(TObject *Sender, TShiftState Shift, int X,int Y)
{
bool q0,q1;
mx1=1.0-divide(X+X,xs-1);
my1=divide(Y+Y,ys-1)-1.0;
sh1=Shift;
q0=sh0.Contains(ssLeft);
q1=sh1.Contains(ssLeft);
if (q1)
{
mx-=(mx1-mx0)*zoom;
my-=(my1-my0)*zoom;
}
mx0=mx1; my0=my1; sh0=sh1;
gl_draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseDown(TObject *Sender, TMouseButton Button,TShiftState Shift, int X, int Y)
{
FormMouseMove(Sender,Shift,X,Y);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseUp(TObject *Sender, TMouseButton Button,TShiftState Shift, int X, int Y)
{
FormMouseMove(Sender,Shift,X,Y);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseWheelDown(TObject *Sender, TShiftState Shift, TPoint &MousePos, bool &Handled)
{
zoom*=1.2;
gl_draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormMouseWheelUp(TObject *Sender, TShiftState Shift, TPoint &MousePos, bool &Handled)
{
zoom/=1.2;
gl_draw();
}
//---------------------------------------------------------------------------
You can ignore most of the code the important stuff is gl_draw() rendering single QUAD covering whole screen and passing zoom and pan position. This code uses old style glBegin/glEnd and default nVidia locations so it may not work on different vendor gfx drivers. The mesh should be in VAO/VBO so the layout locations will match to see how to do it take a look at the link on the end of answer or port the shaders to compatibility profile.
Vertex:
// Vertex
#version 420 core
layout(location=0) in vec2 pos; // glVertex2f <-1,+1>
out smooth vec2 p; // texture end point <0,1>
void main()
{
p=pos;
gl_Position=vec4(pos,0.0,1.0);
}
Fragment:
// Fragment
#version 420 core
uniform sampler2D txrmap; // texture unit for light map
uniform vec2 p0=vec2(0.0,0.0); // mouse position <-1,+1>
uniform float zoom=1.000; // zoom [-]
in smooth vec2 p;
out vec4 col;
void main()
{
int i,n;
vec2 pp;
float x,y,q,xx,yy;
pp=(p*zoom)-p0; // y (-1, 1)
pp.x=(1.75*pp.x)-0.75; // x (-2.5, 1)
for (x=0.0,y=0.0,xx=0.0,yy=0.0,i=0,n=200;(i<n)&&(xx+yy<4.0);i++)
{
q=xx-yy+pp.x;
y=(2.0*x*y)+pp.y;
x=q;
xx=x*x;
yy=y*y;
}
q=float(i)/float(n);
col=texture2D(txrmap,vec2(q,0.5));
// col=vec4(q,q,q,1.0);
}
using this texture as gradient:
![gradient]()
Here result screenshot:
![screenshot]()
In case you need to get started with GLSL (to replace my gl engine stuff) see:
but I am sure there must be tons of tutorials for this in C# so google
If you are interested in color enhancing see:
