如何将顶点缓冲区绑定到 Gfx-rs 中的统一数组？

Question

I am trying to pass a list of Uniform s to a vertex shader using gfx-rs. The data is defined as follows

gfx_defines! {
    vertex Vertex { ... }

    constant MyConst {
        valoo: i32 = "my_val",
    }

    pipeline pipe {
        my_const: gfx::ConstantBuffer<MyConst> = "my_const",
        vbuf: gfx::VertexBuffer<Vertex> = (),
        out: gfx::RenderTarget<ColorFormat> = "Target0",
    }
}

The vertex shader is as follows:

#version 150 core

struct MyConst
{
    uint my_val;
};

in vec2 a_Pos;
in vec3 a_Color;
uniform MyConst my_const[];
out vec4 v_Color;

void main() {
    MyConst cc = my_const[0];
    v_Color = vec4(a_Color, 1.0);
    gl_Position = vec4(a_Pos, 0.0, 1.0);
}

When I introduce the first line in main() , the application crashes with the error:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: DescriptorInit(GlobalConstant("my_const[0].my_val", None))'

Full code

Answer 1

How to bind a vertex buffer to a uniform array [...]

In OpenGL a vertex buffer cannot be "bound" to a uniform array.

A vertex attribute can address a named vertex buffer object (stored in the state vector of the Vertex Array Object), but a uniform can't. See Vertex Specification .

If you want to bind some kind of buffer to some kind of uniform, then you've to use a Uniform Buffer Object which is available since OpenGL 3.1 respectively GLSL version 1.40.

Or you can use a Shader Storage Buffer Object , where the last element of the buffer can be an array of variable size. SSBOs are available since OpenGL 4.3 (GLSL version 4.30) respectively by the extension ARB_shader_storage_buffer_object .

eg:

layout(std430, binding = 0) buffer MyConst
{
    uint my_const[];
};

See also Using Shader Storage Buffer Objects (SSBOs)