Add NIF previewer plugin with Linux-specific fixes

Vendored from github.com/Parapets/mo2-preview_nif and adapted for Linux:

- BSA texture resolution via MO2 virtual tree with case-insensitive
  fallback walk (Linux FS is case-sensitive; NIFs reference textures
  with arbitrary case against files on disk)
- Process-wide cached BSA candidate list, keyed by profile path,
  priority-sorted, filtering disabled mods
- Path backslash normalization before loose-file lookup
- Polygon offset on SLSF1_Decal-flagged shapes to break z-ties with
  coincident base meshes (road decals, moss overlays)
- Opaque framebuffer via glColorMask alpha lock so alpha-blended shapes
  can't bleed the dialog background through the preview area
- QMouseEvent::globalPosition().toPoint() for Qt6 compatibility

Preview dialog behavior (organizercore.cpp):
- Switch previewFile and previewFileWithAlternatives from stack-allocated
  exec() to heap + ApplicationModal + show() + WA_DeleteOnClose.
- Parent passed as nullptr so preview lifetime is decoupled from the
  stack-allocated ModInfoDialog that spawns it. Nested exec() inside
  the enclosing dialog's exec() was softlocking on close.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/libs/preview_nif/src/TextureManager.h b/libs/preview_nif/src/TextureManager.h
new file mode 100644
index 0000000..7ba1c9a
--- /dev/null
+++ b/libs/preview_nif/src/TextureManager.h
@@ -0,0 +1,53 @@
+#pragma once
+
+#include <imoinfo.h>
+#include <gli/gli.hpp>
+#include <QOpenGLTexture>
+#include <QSet>
+#include <QStringList>
+#include <map>
+
+class TextureManager
+{
+public:
+    TextureManager(MOBase::IOrganizer* organizer);
+    ~TextureManager() = default;
+    TextureManager(const TextureManager&) = delete;
+    TextureManager(TextureManager&&) = delete;
+    TextureManager& operator=(const TextureManager&) = delete;
+    TextureManager& operator=(TextureManager&&) = delete;
+
+    void cleanup();
+
+    QOpenGLTexture* getTexture(const std::string& texturePath);
+    QOpenGLTexture* getTexture(QString texturePath);
+
+    QOpenGLTexture* getErrorTexture();
+    QOpenGLTexture* getBlackTexture();
+    QOpenGLTexture* getWhiteTexture();
+    QOpenGLTexture* getFlatNormalTexture();
+
+private:
+    QOpenGLTexture* loadTexture(QString texturePath);
+    QOpenGLTexture* makeTexture(const gli::texture& texture);
+    QOpenGLTexture* makeSolidColor(QVector4D color);
+
+    QString resolvePath(const MOBase::IPluginGame* game, QString path);
+
+    // Build priority-sorted BSA candidate list. Shared process-wide, keyed by
+    // the current instance's profile path so switching instances rebuilds.
+    // Conflict semantics: only active mods contribute, highest profile
+    // priority first, then vanilla archives. No plugin-attachment filter —
+    // matches BodySlide's "load all BSAs" approach which is what MO2's
+    // virtual data tree effectively does.
+    const QStringList& bsaCandidates();
+    void rebuildBsaCandidates();
+
+    MOBase::IOrganizer* m_MOInfo;
+    QOpenGLTexture* m_ErrorTexture = nullptr;
+    QOpenGLTexture* m_BlackTexture = nullptr;
+    QOpenGLTexture* m_WhiteTexture = nullptr;
+    QOpenGLTexture* m_FlatNormalTexture = nullptr;
+
+    std::map<std::wstring, QOpenGLTexture*> m_Textures;
+};