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phase(N.5) Task 7 fixup: BatchData Pack=8 for ulong alignment

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Code quality review caught that BatchData uses Pack=4 but contains a
ulong field. With the current field order (TextureHandle first), offset
0 is always 8-byte aligned so std430 works. But adding a 4-byte field
before TextureHandle without bumping Pack would silently misalign the
GPU struct. Pack=8 makes the alignment requirement explicit and adds
a comment documenting expected std430 offsets.

No runtime change — current offsets (0/8/12) are identical under both
Pack values for this field order.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-05-08 20:29:58 +02:00
parent 86c471d2d1
commit 1b6995d2df
1 changed files with 7 additions and 1 deletions
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8
src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
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@ -80,7 +80,13 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
private int _transparentByteOffset;
#pragma warning restore CS0169
[StructLayout(LayoutKind.Sequential, Pack = 4)]
// std430 layout: ulong TextureHandle (uvec2) at offset 0, uint TextureLayer
// at offset 8, uint Flags at offset 12. Total 16 bytes.
// Pack=8 (not 4) because std430's uvec2 requires 8-byte alignment — Pack=4
// works today by accident (TextureHandle is the first field, so offset 0 is
// always 8-byte aligned), but adding a 4-byte field before TextureHandle
// without bumping Pack would silently misalign the GPU struct.
[StructLayout(LayoutKind.Sequential, Pack = 8)]
private struct BatchData
{
public ulong TextureHandle; // bindless handle (uvec2 in GLSL)