From f918c1d4371ecfa9faf9e124e7bf2d166817b005 Mon Sep 17 00:00:00 2001
From: tim <humbletim@gmail.com>
Date: Thu, 16 May 2024 16:25:05 -0400
Subject: [PATCH] FIRE-33613: [OpenSim] [PBR] Camera cannot be located at
 negative Z

- mitigate SL-20206 Underwater visuals problematic when camera is swung below Z=0
- add support for `OpenSimExtras.MinSimHeight` Simulation Feature to `LLViewerRegion`
- apply region minimum simulation height as gruond plane for camera minZ constraints
---
 indra/newview/llagentcamera.cpp  | 13 ++++++++++++-
 indra/newview/llviewerregion.cpp |  8 +++++++-
 indra/newview/llviewerregion.h   |  4 +++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/indra/newview/llagentcamera.cpp b/indra/newview/llagentcamera.cpp
index ddfa38336f..0c896dc182 100644
--- a/indra/newview/llagentcamera.cpp
+++ b/indra/newview/llagentcamera.cpp
@@ -2145,10 +2145,21 @@ LLVector3d LLAgentCamera::calcCameraPositionTargetGlobal(BOOL *hit_limit)
     }
 // [/RLVa:KB]
 
+// <FS:humbletim> FIRE-33613: [OpenSim] [PBR] Camera cannot be located at negative Z
+    F32 camera_ground_plane = F_ALMOST_ZERO;
+#ifdef OPENSIM
+    // integrate OpenSimExtras.MinSimHeight into the camera ground plane calculation
+    if (auto regionp = LLWorld::getInstance()->getRegionFromPosGlobal(camera_position_global))
+    {
+      camera_ground_plane += regionp->getMinSimHeight();
+    }
+#endif
+// </FS:humbletim>
+
     // Don't let camera go underground
     F32 camera_min_off_ground = getCameraMinOffGround();
     camera_land_height = LLWorld::getInstance()->resolveLandHeightGlobal(camera_position_global);
-    F32 minZ = llmax(F_ALMOST_ZERO, camera_land_height + camera_min_off_ground);
+    F32 minZ = llmax(camera_ground_plane, camera_land_height + camera_min_off_ground);
     if (camera_position_global.mdV[VZ] < minZ)
     {
         camera_position_global.mdV[VZ] = minZ;
diff --git a/indra/newview/llviewerregion.cpp b/indra/newview/llviewerregion.cpp
index 920ec2f8fd..efba2669ef 100755
--- a/indra/newview/llviewerregion.cpp
+++ b/indra/newview/llviewerregion.cpp
@@ -675,7 +675,8 @@ LLViewerRegion::LLViewerRegion(const U64 &handle,
 // </FS:Beq>
     // <FS:CR> Aurora Sim
     mWidth(region_width_meters),
-    mWidthScaleFactor(region_width_meters / REGION_WIDTH_METERS) // <FS:Ansariel> FIRE-19563: Scaling for OpenSim VarRegions
+    mWidthScaleFactor(region_width_meters / REGION_WIDTH_METERS), // <FS:Ansariel> FIRE-19563: Scaling for OpenSim VarRegions
+    mMinSimHeight(0.f) // <FS:humbletim> FIRE-33613: [OpenSim] [PBR] Camera cannot be located at negative Z
 {
     // Moved this up... -> mWidth = region_width_meters;
 // </FS:CR>
@@ -2632,6 +2633,11 @@ void LLViewerRegion::setSimulatorFeatures(const LLSD& sim_features)
     mMaxTEs   = LLAvatarAppearanceDefines::ETextureIndex::TEX_NUM_INDICES;
 #endif // OPENSIM
 // </FS:Beq>
+// <FS:humbletim> FIRE-33613: [OpenSim] [PBR] Camera cannot be located at negative Z
+#ifdef OPENSIM
+    mMinSimHeight = !mSimulatorFeatures.has("OpenSimExtras") ? 0.0f : mSimulatorFeatures["OpenSimExtras"]["MinSimHeight"].asReal();
+#endif
+// </FS:humbletim>
 }
 
 //this is called when the parent is not cacheable.
diff --git a/indra/newview/llviewerregion.h b/indra/newview/llviewerregion.h
index 928a6909d8..49138d3243 100644
--- a/indra/newview/llviewerregion.h
+++ b/indra/newview/llviewerregion.h
@@ -249,6 +249,7 @@ public:
 
     F32 getWidth() const                        { return mWidth; }
     F32 getWidthScaleFactor() const             { return mWidthScaleFactor; } // <FS:Ansariel> FIRE-19563: Scaling for OpenSim VarRegions
+    F32 getMinSimHeight() const                 { return mMinSimHeight; } // <FS:humbletim/> FIRE-33613: [OpenSim] [PBR] Camera cannot be located at negative Z
 
     // regions are expensive to release, this function gradually releases cache from memory
     static void idleCleanup(F32 max_update_time);
@@ -548,7 +549,8 @@ public:
     S32         mLastUpdate; //last time called idleUpdate()
     F32         mWidthScaleFactor; // <FS:Ansariel> FIRE-19563: Scaling for OpenSim VarRegions
     S32         mMaxBakes; // <FS:Beq/> store max bakes on the region
-    S32         mMaxTEs; // <FS:Beq/> store max bakes on the region
+    S32         mMaxTEs; // <FS:Beq/> store max texture entries on the region
+    F32         mMinSimHeight; // <FS:humbletim/> FIRE-33613: [OpenSim] [PBR] Camera cannot be located at negative Z
     // simulator name
     std::string mName;
     std::string mZoning;