concinnity_core/
platform.rs

1//! The shader `Platform` selector: which shader source language the running
2//! backend consumes. Pure (no I/O, cfg-resolved), so it sits in the runtime
3//! foundation rather than the build module -- the engine picks a `Shader` stage's
4//! current-platform source at runtime, and the build pipeline reuses the same
5//! selection at compile time.
6
7/// Shader source language families supported by the engine. Each variant
8/// matches one render backend: Metal, HLSL (DirectX), or GLSL (Vulkan).
9///
10/// A given build only ever constructs the variant for its own backend (see
11/// `current`), so the other two read as never-constructed; `key` still matches
12/// all three, so the type stays whole.
13#[derive(Debug, Clone, Copy, PartialEq, Eq)]
14pub enum Platform {
15    /// Metal Shading Language, for the Metal backend.
16    Metal,
17    /// HLSL, for the DirectX backend.
18    Hlsl,
19    /// GLSL, for the Vulkan backend.
20    Glsl,
21}
22
23impl Platform {
24    /// The shader platform the current binary's rendering backend was built
25    /// for. Resolved from the backend cfg (see build.rs), not the target OS, so
26    /// a Windows Vulkan build correctly selects GLSL rather than HLSL.
27    pub fn current() -> Self {
28        #[cfg(backend_metal)]
29        {
30            Platform::Metal
31        }
32        #[cfg(backend_dx)]
33        {
34            Platform::Hlsl
35        }
36        #[cfg(backend_vk)]
37        {
38            Platform::Glsl
39        }
40    }
41
42    /// String key used in the `sources` map of a `Shader` stage.
43    pub fn key(self) -> &'static str {
44        match self {
45            Platform::Metal => "metal",
46            Platform::Hlsl => "hlsl",
47            Platform::Glsl => "glsl",
48        }
49    }
50
51    /// Whether a shader source with the given file extension is usable on this
52    /// platform. The matching extension (`metal` / `hlsl` / `glsl`) is accepted;
53    /// a non-matching shader extension is rejected so a single-path source
54    /// authored for one backend doesn't get fed to another; an unknown
55    /// extension is accepted by default (the build step surfaces a real compile
56    /// error later if the file truly can't be built).
57    ///
58    /// Shared by the per-platform source selection of `Shader` stages and
59    /// `SdfVolume` so both apply identical fallback rules.
60    pub fn accepts_ext(self, ext: &str) -> bool {
61        !matches!(ext, "metal" | "hlsl" | "glsl") || ext == self.key()
62    }
63}
64
65#[cfg(test)]
66mod tests {
67    use super::*;
68
69    #[test]
70    fn platform_key_and_accepts_ext_cover_all_variants() {
71        assert_eq!(Platform::Metal.key(), "metal");
72        assert_eq!(Platform::Hlsl.key(), "hlsl");
73        assert_eq!(Platform::Glsl.key(), "glsl");
74
75        // The matching extension is accepted; another backend's shader
76        // extension is rejected; an unknown extension is accepted by default.
77        assert!(Platform::Metal.accepts_ext("metal"));
78        assert!(!Platform::Metal.accepts_ext("hlsl"));
79        assert!(!Platform::Metal.accepts_ext("glsl"));
80        assert!(Platform::Hlsl.accepts_ext("hlsl"));
81        assert!(!Platform::Hlsl.accepts_ext("metal"));
82        assert!(Platform::Glsl.accepts_ext("glsl"));
83        assert!(!Platform::Glsl.accepts_ext("hlsl"));
84        assert!(Platform::Metal.accepts_ext("txt"));
85    }
86}
concinnity_core/platform.rs

concinnity_core/
platform.rs
