HSDollyCam/HS_CamFov.lsl

/*
    HS_DollyCam - FOV Helper
    - Central place that actually sends RLVa @setcam_fov
    - Receives CE_CMD_FOV link messages: "rad|quiet" or "rad|quiet|flags"
    - Dedupe + optional force flag (and optional sync hook via CE_CMD_GET_STATE if you want later)

    Put this script into the HUD linkset.
*/

integer CE_CMD_FOV       = 1040; // payload: rad|quiet|flags(optional)
integer CE_CMD_RELEASE   = 1001; // for cleanup
integer CE_CMD_GET_STATE = 1060; // optional sync (not required for basic)
integer CE_EVT_STATE     = 2060; // optional sync response

// --- RLVa ---
string RLV_FOV_CMD = "setcam_fov"; // if your viewer uses another name, change here
float  RLV_FOV_MIN_DEG = 10.0;
float  RLV_FOV_MAX_DEG = 179.0;    // allow wide values (e.g. rad ~ 3.0)

// flags (optional third field)
integer FOVF_SYNC  = 1; // request state before deciding (optional)
integer FOVF_FORCE = 2; // bypass dedupe

// runtime
key   gOwner;

float gLastSentRad = -1.0;
float gEpsRad      = 0.0005; // ~0.03deg
float gMinInterval = 0.02;   // small safety throttle (senders already throttle)
float gLastSendT   = 0.0;

// optional sync
integer gSyncPend = FALSE;
string  gSyncReq  = "";
float   gSyncRad  = 0.0;
integer gSyncQuiet= 1;
integer gSyncFlags= 0;

// debug (keep OFF in production)
integer DEBUG_FOV = FALSE;
dbg(string s){ if (DEBUG_FOV) llOwnerSay("[FOV] " + s); }

float clampf(float v, float lo, float hi){ if (v<lo) return lo; if (v>hi) return hi; return v; }
float deg2rad(float d){ return d * PI / 180.0; }
float rad2deg(float r){ return r * 180.0 / PI; }

float clampFovRad(float rad)
{
    float deg = rad2deg(rad);
    deg = clampf(deg, RLV_FOV_MIN_DEG, RLV_FOV_MAX_DEG);
    return deg2rad(deg);
}

integer camTrackOk()
{
    return ((llGetPermissions() & PERMISSION_TRACK_CAMERA) && (llGetPermissionsKey() == gOwner));
}

float getViewerFovRadOrNeg()
{
    if (!camTrackOk()) return -1.0;
    float f = llGetCameraFOV();
    if (f <= 0.0001) return -1.0;
    return clampFovRad(f);
}

sendRlvaFov(float rad, integer quiet, integer flags)
{
    rad = clampFovRad(rad);

    float now = llGetTime();
    if ((now - gLastSendT) < gMinInterval) {
        // tiny global throttle (prevents double-sends from multiple sources same frame)
        if (!(flags & FOVF_FORCE)) return;
    }

    if (!(flags & FOVF_FORCE)) {
        // Prefer dedupe against ACTUAL viewer FOV (resists manual viewer changes)
        float cur = getViewerFovRadOrNeg();
        if (cur > 0.0) {
            if (llFabs(rad - cur) < gEpsRad) return; // viewer already at this FOV
        } else {
            // fallback: dedupe against last value we sent
            if (gLastSentRad > 0.0 && llFabs(rad - gLastSentRad) < gEpsRad) return;
        }
    }

    gLastSendT = now;
    gLastSentRad = rad;

    // RLVa commands are sent via owner chat from attachment scripts.
    // Many viewers hide "@..." automatically.
    string cmd = "@" + RLV_FOV_CMD + ":" + (string)rad + "=force";

    if (!quiet) {
        dbg("send " + cmd + "  (" + (string)rad2deg(rad) + " deg)");
    }

    llOwnerSay(cmd);
}

string newReqId()
{
    // unique enough
    return "FOVSYNC:" + (string)llGetUnixTime() + ":" + (string)((integer)llFrand(1000000.0));
}

requestSyncThenMaybeSend(float rad, integer quiet, integer flags)
{
    // optional path: ask Core for state (which can include fov if you patched it),
    // then decide whether to send. Good for "manual viewer change" corrections
    gSyncPend  = TRUE;
    gSyncRad   = rad;
    gSyncQuiet = quiet;
    gSyncFlags = flags;
    gSyncReq   = newReqId();

    llMessageLinked(LINK_SET, CE_CMD_GET_STATE, gSyncReq, gOwner);
}

default
{
    state_entry()
    {
        gOwner = llGetOwner();
    }

    on_rez(integer sp)
    {
        gOwner = llGetOwner();
        gLastSentRad = -1.0;
        gLastSendT = 0.0;
        gSyncPend = FALSE;
        gSyncReq = "";
    }

    attach(key id)
    {
        gOwner = llGetOwner();
        if (id == NULL_KEY) {
            // detach cleanup
            gLastSentRad = -1.0;
            gLastSendT = 0.0;
            gSyncPend = FALSE;
            gSyncReq = "";
        }
    }

    link_message(integer sender, integer num, string str, key id)
    {
        if (num == CE_CMD_RELEASE) {
            // reset internal state; do NOT spam RLVa on release
            gLastSentRad = -1.0;
            gLastSendT = 0.0;
            gSyncPend = FALSE;
            gSyncReq = "";
            return;
        }

        if (num == CE_CMD_FOV) {
            if (id != gOwner) return;

            list p = llParseString2List(str, ["|"], []);
            integer L = llGetListLength(p);
            if (L < 1) return;

            float rad = (float)llList2String(p, 0);
            integer quiet = 1;
            if (L >= 2) quiet = (integer)llList2String(p, 1);

            integer flags = 0;
            if (L >= 3) flags = (integer)llList2String(p, 2);

            // If you don't want sync at all, just ignore FOVF_SYNC and always send:
            if (flags & FOVF_SYNC) {
                requestSyncThenMaybeSend(rad, quiet, flags);
            } else {
                sendRlvaFov(rad, quiet, flags);
            }
            return;
        }

        // optional sync response (only if you patched Core to append fov to CE_EVT_STATE)
        if (num == CE_EVT_STATE) {
            if (!gSyncPend) return;

            list p2 = llParseString2List(str, ["|"], []);
            if (llGetListLength(p2) < 1) return;

            string reqId = llList2String(p2, 0);
            if (reqId != gSyncReq) return;

            // field 4 (index 4) expected to be fov rad if available
            float curFov = -1.0;
            if (llGetListLength(p2) >= 5) {
                curFov = (float)llList2String(p2, 4);
                if (curFov > 0.0001) curFov = clampFovRad(curFov);
                else curFov = -1.0;
            }
            
            // If Core did not provide a usable FOV, force-send to avoid stale cache dedupe
            if (curFov < 0.0 && !(gSyncFlags & FOVF_FORCE)) {
                gSyncFlags = gSyncFlags | FOVF_FORCE;
            }            

            // clear pending first
            gSyncPend = FALSE;
            gSyncReq  = "";

            // if we have current fov, use it for dedupe decision
            if (curFov > 0.0 && !(gSyncFlags & FOVF_FORCE)) {
                float want = clampFovRad(gSyncRad);
                if (llFabs(want - curFov) < gEpsRad) return;
            }

            sendRlvaFov(gSyncRad, gSyncQuiet, gSyncFlags);
            return;
        }
    }
}