global variable used in functions will be converted to parameters in metal shaders, sometimes resulting in parameters passed in wrong order.

[mattiasljungstrom]

This isn't a major issue, but something I noticed and figured it's worth documenting. No error is shown, instead you get corrupted results during rendering.

Example code (bad):

sampler2D texture;

vec4 calc_something(vec2 uv, float scale)
{
    vec4 color = texture(texture, uv) * scale;
    return color;
}

The generated shader code on metal will add the sampler as an argument on the end of the calc_something() function, but will call it with the sampler as the first argument...

The issue can be avoided by passing in all parameters in the code, like this:

sampler2D texture;

vec4 calc_something(sampler2D tex, vec2 uv, float scale)
{
    vec4 color = texture(tex, uv) * scale;
    return color;
}

[floooh]

Hmm, that's annoying :) Strange that it doesn't generate an error though.