Pointer into input struct of Compute Shader

Question

Once more I have a problem with my compute shader... I would like to pass a structure containing a pointer into a compute shader. This is my structure example:

struct couleurStruct {
    float r;
    float g;
    float b;
    float a;
    float *x;
};

Here is my SSBO initialization :

couleurStruct *coul;
coul = (couleurStruct *)glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, 1 * sizeof(couleurStruct), bufMask);
//coul->x = (float *)glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, 1 * sizeof(float), bufMask);

coul->r = 0.0;
coul->g = 1.0;
coul->b = 0.0;
coul->a = 1.0;
coul->x[0] = 0.5;

glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);

glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, structBuffer);

I tried a lot of different initializations but without success...

So, is there a way to allocate all the memory needed (because I know the memory I will need inside each of the arrays pointed by my pointers) and pass it to the compute shader? Or is it really impossible to pass a pointer to a compute shader?

Thank you for your help!

Answer 1

Shaders in OpenGL (and Vulkan/D3D for that matter) cannot have pointers. The most you can do is provide an index into some other data structure. So you could make x an index into some other array. Though it's not clear exactly why it needs to be a pointer.