How can I have an array uniform buffer block in glsl?

Question

The error I get with the following declaration of a buffer is:

Binding point for uniform block must be equal or greater than 0 and less than: GL_MAX_UNIFORM_BUFFER_BINDINGS.

My GL_MAX_UNIFORM_BUFFER_BINDINGS is 90. I want 128 of the following structs:

layout(binding = 3, std140) uniform lightsBuffer
{
    mat4 viewMatrix;
    vec3 colour;
    float padding;
}lights[128];

It seems I've created 128 of these structs each at different binding points. How do I have the array of 128 structs at binding 2?

Edit: Is it like this:

layout(binding = 3, std140) uniform lightsBuffer
{
    struct Light
    {
        mat4 viewMatrix;
        vec3 colour;
        float padding;
    }lights[128];
};

@Rabbid76 Can I define the Light struct inside or do I have to define struct Light { } beforehand, and then do what you said? — Zebrafish
– Zebrafish, Commented Oct 4, 2020 at 16:23

Nicol Bolas · Accepted Answer · 2020-10-04 16:23:56Z

2

That's not a struct; it's a uniform block. You can tell because you didn't use the keyword struct ;) So what you're creating is an array of uniform blocks.

If you want an array within a uniform block, you can create that using standard syntax:

layout(...) uniform lightsBuffer
{
    StructName lights[128];
};

Where StructName is a previously-defined struct.

Can I define the Light struct inside

No. Why would you want to?

answered Oct 4, 2020 at 16:23

Nicol Bolas

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3 Comments

Zebrafish Over a year ago

I see, define the struct beforehand. It cannot be inside the block like I did?

Zebrafish Over a year ago

@Rabbid76 What I meant was something like uniform lightsBuffer { struct Light { float a; } lights[128]; }; This seems to have worked in my program.

Nicol Bolas Over a year ago

@Zebrafish: Then your compiler has a bug. The grammar technically allows it, but there's a explicit statement in the text forbidding it: "Structure definitions cannot be nested inside a block"

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