Issue with the GLSL Compiler on M1 OpenGL driver?

Hello,

I am doing a cross-platform project that uses C++ and OpenGL ( I know I should be using MoltenVK or Metal, but OpenGL is nice and simple for starting out and is cross platform). I am also doing most of my development on a M1 Macbook Pro, which supports up to OpenGL 4.1.

The M1 also only supports up to 16 active fragment shader samplers ( maximum number of supported image units)

I am currently working on a batch rendering system that uses an array of textures thats uploaded to the GPU and the shader can switch based off of the index into a sampler array. Heres the shader that I am using ( the vertex and fragment shaders are combined, but the program parses them separately) :

#type vertex
#version 410 core

layout(location = 0) in vec3 a_Position;
layout(location = 1) in vec4 a_Color;
layout(location = 2) in vec2 a_TexCoord;
layout(location = 3) in float a_TexIndex;
layout(location = 4) in float a_TilingFactor;

uniform mat4 u_ViewProjection;

out vec4 v_Color;
out vec2 v_TexCoord;
out float v_TexIndex;
out float v_TilingFactor;

void main()
{
    v_Color = a_Color;
    v_TexCoord = a_TexCoord;
    v_TexIndex = a_TexIndex;
    v_TilingFactor = a_TilingFactor;
    gl_Position = u_ViewProjection * vec4(a_Position, 1.0);
}

#type fragment
#version 410 core

layout(location = 0) out vec4 color;

in vec4 v_Color;
in vec2 v_TexCoord;
in float v_TexIndex;
in float v_TilingFactor;

uniform sampler2D u_Textures[16];

void main()
{
    color = texture(u_Textures[int(v_TexIndex)], v_TexCoord * v_TilingFactor) * v_Color;
}

However, when the program runs I get this message: UNSUPPORTED (log once): POSSIBLE ISSUE: unit 2 GLD_TEXTURE_INDEX_2D is unloadable and bound to sampler type (Float) - using zero texture because texture unloadable

I double and triple checked my code and im binding everything correctly to the shader (if im not feel free to point it out :), and the only thing I found on the web relating to this error was saying that it was an error within the GLSL compiler on the new M1s. Is this true? Or is it a code issue?

Thanks

side note: I am using EMACS to run Cmake and do C++ development, so if you try and test my project on Xcode and it doesnt include the shaders its most likely a Cmake/Xcode copy issue.

  • I am encountering this same problem on my M1 Pro MacBook.

  • I have the same issue on a new MAC Mini - since it seems to work fine on other systems, it seems like a compiler issue on the M1s.

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Did you manage to solve this problem?

  • Nope. I ended up using a bunch of if statements to get it run properly

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