OpenCL to OpenGL texture problems

问题

I'm trying to use OpenCL to draw to a cl_image that I got from a OpenGL texture and then render that texture. The problem is when I run my code on CL_DEVICE_TYPE_CPU it works fine however when I run on CL_DEVICE_TYPE_GPU the texture appears to be some random pixels. I'm new to OpenCL and not sure what's goin on so I'll post code below, also using OpenCL on OSX.

Host Code:

#import "GLView.h"
#import <GLKit/GLKit.h>
#import <OpenCL/OpenCL.h>
#import "kernel.cl.h"

#define WIDTH 500
#define HEIGHT 500

static GLfloat squareVertexData[] =
{
    -0.5f, -0.5f, 0.0f,     0.0f, 0.0f,
    0.5f, -0.5f, 0.0f,      1.0f, 0.0f,
    0.5f, 0.5f, 0.0f,       1.0f, 1.0f,
    -0.5f, -0.5f, 0.0f,     0.0f, 0.0f,
    0.5f, 0.5f, 0.0f,       1.0f, 1.0f,
    -0.5f, 0.5f, 0.0f,      0.0f, 1.0f
};

@interface GLView ()

@property (strong, nonatomic) GLKBaseEffect *effect;
@property (nonatomic) GLuint vertexArray;
@property (nonatomic) GLuint vertexBuffer;
@property (nonatomic) GLuint tex;
@property (nonatomic) cl_image clImage;
@property (nonatomic) dispatch_queue_t queue;

@end

@implementation GLView

#pragma mark - Lifecycle methods

- (void)awakeFromNib
{
    NSOpenGLPixelFormatAttribute attrs[] =
    {
        NSOpenGLPFADoubleBuffer,
        NSOpenGLPFAOpenGLProfile,
        NSOpenGLProfileVersion3_2Core,
        NSOpenGLPFAColorSize, 8,
        NSOpenGLPFAAlphaSize, 8,
        0
    };

    NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attrs];
    [self setPixelFormat:pixelFormat];

    NSOpenGLContext *context = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];
    CGLEnable([context CGLContextObj], kCGLCECrashOnRemovedFunctions);
    [self setOpenGLContext:context];
}

- (void)dealloc
{
    [self.openGLContext makeCurrentContext];

    glDeleteBuffers(1, &_vertexBuffer);
    glDeleteVertexArrays(1, &_vertexArray);

    glDeleteTextures(1, &_tex);
    gcl_release_image(self.clImage);
}

#pragma mark - NSOpenGLView methods

- (void)prepareOpenGL
{
    GLint swapInterval = 1;
    [self.openGLContext setValues:&swapInterval forParameter:NSOpenGLCPSwapInterval];

    glGenVertexArrays(1, &_vertexArray);
    glBindVertexArray(self.vertexArray);

    glGenBuffers(1, &_vertexBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(squareVertexData), squareVertexData, GL_STATIC_DRAW);

    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 20, (char *)NULL + (0));

    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
    glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 20, (char *)NULL + (12));

    glBindVertexArray(0);

    self.effect = [[GLKBaseEffect alloc] init];
    self.effect.transform.projectionMatrix = GLKMatrix4MakeOrtho(-1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f);

    glGenTextures(1, &_tex);
    glBindTexture(GL_TEXTURE_2D, self.tex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, WIDTH, HEIGHT, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

    self.effect.texture2d0.name = self.tex;

    CGLShareGroupObj sharegroup = CGLGetShareGroup(self.openGLContext.CGLContextObj);
    gcl_gl_set_sharegroup(sharegroup);

    self.clImage = gcl_gl_create_image_from_texture(GL_TEXTURE_2D, 0, self.tex);

    self.queue = gcl_create_dispatch_queue(CL_DEVICE_TYPE_GPU, NULL);

    dispatch_sync(self.queue, ^{

        cl_ndrange range = {
            2,
            { 0 },
            { WIDTH, HEIGHT },
            { 0 }
        };

        mykernel_kernel(&range, self.clImage);
    });

    glClearColor(0.65f, 0.65f, 0.65f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glBindVertexArray(self.vertexArray);

    [self.effect prepareToDraw];

    glDrawArrays(GL_TRIANGLES, 0, 6);

    glBindVertexArray(0);

    [self.openGLContext flushBuffer];
}

@end

Kernel Code:

kernel void mykernel(write_only image2d_t image)
{
    size_t x = get_global_id(0);
    size_t y = get_global_id(1);

    uint4 color;
    color.x = 255;
    color.w = 255;

    write_imageui(image, (int2) (x,y), color);
}