Ports WorldBuilder's GL sampler-object pattern
(references/WorldBuilder/Chorizite.OpenGLSDLBackend/OpenGLGraphicsDevice.cs:115-132,
SkyboxRenderManager.cs:312). Two persistent samplers (Repeat +
ClampToEdge) are created once at GL init; the sky pass binds the
appropriate one to texture unit 0 per submesh instead of mutating
per-texture GL_TEXTURE_WRAP_S/T state.
Why this is better than the prior M1 track-and-restore hack:
1. Sampler state is decoupled from texture state. Two renderers can
share the same texture handle but sample it with different wrap
modes simultaneously and safely — sampler state at the bind point
overrides the texture's own wrap parameters.
2. No bookkeeping. Drops the HashSet<uint> clamped-textures tracking
and the end-of-pass restore loop. The only restore needed is
BindSampler(0, 0) to release unit 0 back to per-texture state.
3. Constant cost. Sampler objects are created once per GL context,
not per draw. Filter modes match TextureCache's upload defaults
(Linear/Linear, no mipmaps) so the binding is purely a wrap-mode
selection.
Field count: SkyRenderer.cs -28 lines, +14 lines. GameWindow.cs gets
the SamplerCache field + ctor + Dispose. SkyRenderer disposed before
SamplerCache so the sky teardown path doesn't reference a freed
sampler handle.
dotnet build green, dotnet test green: 695 / 393 / 243 = 1331 passed
(unchanged).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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