Function RenderPostProcessShaderPicker

port/gui/PortMenu.cpp:142–298

Render the post-process shader picker as a single combo widget that opens onto a tree of bundled + user-installed shaders. Drives the two LUS cvars LUS::Run reads each frame: gPostProcessEnabled (int, 0/1) gPostProcessShader (string, short name as accepted by Fast::LoadPostProcessShader) The combo's preview text reflects the current cvar state, so a fresh launch picks up the previously-selected s

// fresh launch picks up the previously-selected shader without the
// picker needing to know about state-restore.
void RenderPostProcessShaderPicker(WidgetInfo& /*widget*/) {
    const bool enabled = CVarGetInteger("gPostProcessEnabled", 0) != 0;
    const char* currentRaw = CVarGetString("gPostProcessShader", "");
    const std::string current = currentRaw ? currentRaw : std::string();

    std::string preview = "Off";
    if (enabled && !current.empty()) {
        if (const char* friendly = PostProcessShaderLabel(current)) {
            preview = friendly;
        } else {
            preview = current;
        }
    }

    ImGui::TextUnformatted("Post-Process Shader");
    ImGui::SetNextItemWidth(ImGui::GetContentRegionAvail().x);
    if (!ImGui::BeginCombo("##gPostProcessShaderPicker", preview.c_str())) {
        return;
    }

    // Filter input persists across frames inside the open popup
    // only — closing the combo clears it. ImGui draws the combo
    // content inside its own internal child window each frame, so
    // a static-local is the simplest persistence story without a
    // companion cvar.
    static char filterBuf[128] = "";
    ImGui::SetNextItemWidth(ImGui::GetContentRegionAvail().x);
    ImGui::InputTextWithHint("##gPostProcessShaderFilter", "Filter...", filterBuf, sizeof(filterBuf));
    const std::string filter = filterBuf;

    auto matchesFilter = [&filter](const std::string& s) -> bool {
        if (filter.empty()) {
            return true;
        }
        // Case-insensitive substring match.
        std::string hay = s;
        std::string needle = filter;
        std::transform(hay.begin(), hay.end(), hay.begin(),
                       [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
        std::transform(needle.begin(), needle.end(), needle.begin(),
                       [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
        return hay.find(needle) != std::string::npos;
    };

    auto selectShader = [](const std::string& name) {
        if (name.empty()) {
            CVarSetInteger("gPostProcessEnabled", 0);
            return;
        }
        CVarSetString("gPostProcessShader", name.c_str());
        CVarSetInteger("gPostProcessEnabled", 1);

        // Trigger the Low Resolution Mode warn modal when the picked
        // shader expects a native-resolution source FB but the user's
        // current latched mode is "off". The shader still loads — we
        // never block selection — but the modal nudges them toward
        // enabling N64 mode + restart so the picture isn't a tiny
        // render in the corner of the window.