Ole André Vadla Ravnås
02ca1ff8a5
glslang and SPIRV-Cross build under neither SwiftPM nor Xcode, so CI makes them into an xcframework and publishes it against a tag. The manifest names that artifact; a build downloads it and needs nothing local.
62 lines
2.3 KiB
Swift
62 lines
2.3 KiB
Swift
#if canImport(Metal)
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import CShaderTranslate
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import Foundation
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/// Turns GLSL written at runtime into Metal Shading Language, so an effect
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/// typed into a snippet reaches a Metal host without a build step. The GTK
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/// host needs none of this: OpenGL takes the GLSL as it stands.
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public enum ShaderTranslator {
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/// The preamble every authored effect is compiled against, naming the
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/// uniforms it may read. It matches what `LumaShaderCompiler` prepends at
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/// build time, so an effect reads the same whether it was authored here or
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/// shipped in `Shaders/`.
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/// What a screen-filling effect is compiled against: the vertex stage is
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/// the host's, handing down only where on screen the pixel sits.
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public static var preamble: String {
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"""
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\(ShaderVocabulary.header)
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layout(location = 0) in vec2 v_uv;
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layout(location = 0) out vec4 frag_color;
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\(ShaderVocabulary.uniformBlock)
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"""
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}
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/// Answers the Metal source for `body`, which carries only its own helpers
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/// and `main()`.
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public static func metalSource(for body: String, entryPoint: String) throws -> String {
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try metalSource(forComplete: preamble + body, stage: .fragment, entryPoint: entryPoint)
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}
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public enum Stage: Int32 {
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case vertex = 0
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case fragment = 1
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}
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/// Translates a whole shader, preamble and all, for callers that build
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/// their own -- a canvas whose attributes the author declared.
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public static func metalSource(forComplete glsl: String, stage: Stage, entryPoint: String) throws -> String {
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var message: UnsafeMutablePointer<CChar>?
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let translated = luma_shader_translate_to_msl(glsl, stage.rawValue, entryPoint, &message)
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guard let translated else {
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let detail = message.map { String(cString: $0) } ?? "no detail"
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message.map { free($0) }
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throw ShaderTranslationError(message: detail)
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}
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defer { free(translated) }
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return String(cString: translated)
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}
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}
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/// Carries what the shader compiler said, so a mistyped effect is reported
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/// where it was written rather than drawing nothing.
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public struct ShaderTranslationError: Error, CustomStringConvertible {
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public let message: String
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public var description: String { message }
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}
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#endif
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