// Campaign V slice V2 shared preamble (docs/plans/2026-07-27-vulkan-campaign.md
// §3.4, §5.2). GL has no #include, so AcDream.App.Rendering.Shader
// concatenates this file's text into every shader source that opts in
// (Shader(gl, vertPath, fragPath, includeCommonPreamble: true)), inserted
// right after the leading #version / #extension block so it can declare new
// layout bindings and macros before the rest of the shader body runs.
//
// --- set 1 (uniform buffers) ------------------------------------------------
// GL keeps the SSBO and UBO binding-number namespaces separate, so today's
// SceneLighting UBO (binding=1) never collides with BatchBuffer's SSBO
// (also binding=1). Vulkan has ONE binding namespace per set, so the Vulkan
// backend (from V6 on) moves every uniform buffer to its own set (1) to keep
// both binding numbers. ACDREAM_UBO_SET is a no-op under GL today and is
// redefined to `set = 1,` when the same source is compiled for Vulkan, so
// applying it to every UBO layout now costs nothing and needs no source edit
// at the call sites later.
#define ACDREAM_UBO_SET

// --- set 0 binding 9 / set 2 (the global texture table) --------------------
// GL emulates Vulkan's set 2 variable-count sampled-texture descriptor array
// (GpuBindingModel.TextureTableSet) with a plain storage buffer of packed
// GL_ARB_bindless_texture handles at set 0 binding 9
// (GpuBindingModel.StorageTextureTable). A batch/pass no longer carries a
// 64-bit bindless handle directly into its GPU-visible struct; it carries a
// small integer slot index into this table instead, which is what makes the
// CPU-side data model backend-neutral (Campaign V slice V2). The table itself
// — and every per-renderer GL-side handle-slot allocator that fills it
// (WbDrawDispatcher, EnvCellRenderer, TerrainModernRenderer, ParticleRenderer)
// — is deleted once each renderer moves onto IGpuDevice's own retirement-gated
// table at V4c/V4d/V4e; see the campaign doc's §5.2 for why V2 cannot reach
// that table yet.
layout(std430, binding = 9) readonly buffer TextureTableBuf {
    uvec2 gTextureTable[];
};

// Looks up the packed bindless handle for table slot `idx`. Callers still
// wrap the result in `sampler2DArray(...)` themselves at the use site (kept
// explicit rather than folded into one sampler-returning macro) because every
// existing call site already follows that exact pattern and a function cannot
// return an opaque sampler type built from a runtime value in GLSL.
#define ACDREAM_TEXTURE_HANDLE(idx) gTextureTable[idx]

// Campaign V slice V6d: samples a table slot that holds a plain 2-D texture.
//
// The two backends disagree about what a 2-D table entry IS, and this macro is
// the one place that difference lives. Under GL a bindless handle carries its
// own texture type, so a GL_TEXTURE_2D entry is reconstructed as a sampler2D
// and read with a 2-component UV. Under Vulkan the table is one descriptor
// array whose element type is fixed at sampler2DArray, so the same entry is a
// one-layer array read at layer 0 (see tools/ShaderCompiler/VulkanGlslPreamble.cs).
//
// That asymmetry is deliberate and is what keeps the retained UI's textures
// exactly as they are on GL — including the paperdoll/appraisal FBO colour
// texture, which is an externally-owned GL_TEXTURE_2D registered by the §7.1
// transitional seam and cannot be made an array before V4g moves its renderer.
#define ACDREAM_SAMPLE_2D(idx, uv) texture(sampler2D(gTextureTable[idx]), uv)