1 files changed, 45 insertions, 24 deletions

diff --git a/indra/newview/llviewertexture.cpp b/indra/newview/llviewertexture.cpp
index 452d6f2c04..99f8db00f2 100644
--- a/indra/newview/llviewertexture.cpp
+++ b/indra/newview/llviewertexture.cpp
@@ -511,44 +511,52 @@ void LLViewerTexture::updateClass()
 
     F32 over_pct = (used - target) / target;
 
-    bool is_low = over_pct > 0.f;
+    bool is_sys_low = isSystemMemoryLow();
+    bool is_low = is_sys_low || over_pct > 0.f;
 
-    if (isSystemMemoryLow())
+    static bool was_low = false;
+    static bool was_sys_low = false;
+
+    if (is_low && !was_low)
+    {
+        // slam to 1.5 bias the moment we hit low memory (discards off screen textures immediately)
+        sDesiredDiscardBias = llmax(sDesiredDiscardBias, 1.5f);
+
+        if (is_sys_low)
+        { // if we're low on system memory, emergency purge off screen textures to avoid a death spiral
+            LL_WARNS() << "Low system memory detected, emergency downrezzing off screen textures" << LL_ENDL;
+            for (auto& image : gTextureList)
+            {
+                gTextureList.updateImageDecodePriority(image, false /*will modify gTextureList otherwise!*/);
+            }
+        }
+    }
+
+    was_low = is_low;
+    was_sys_low = is_sys_low;
+
+    if (is_low)
     {
-        is_low = true;
-        // System RAM is low -> ramp up discard bias over time to free memory
+        // ramp up discard bias over time to free memory
         if (sEvaluationTimer.getElapsedTimeF32() > MEMORY_CHECK_WAIT_TIME)
         {
             static LLCachedControl<F32> low_mem_min_discard_increment(gSavedSettings, "RenderLowMemMinDiscardIncrement", .1f);
-            sDesiredDiscardBias += (F32) low_mem_min_discard_increment * (F32) gFrameIntervalSeconds;
+            sDesiredDiscardBias += (F32)low_mem_min_discard_increment * (F32)gFrameIntervalSeconds;
             sEvaluationTimer.reset();
         }
     }
     else
     {
-        sDesiredDiscardBias = llmax(sDesiredDiscardBias, 1.f + over_pct);
+        // don't execute above until the slam to 1.5 has a chance to take effect
+        sEvaluationTimer.reset();
 
+        // lower discard bias over time when free memory is available
         if (sDesiredDiscardBias > 1.f && over_pct < 0.f)
         {
             sDesiredDiscardBias -= gFrameIntervalSeconds * 0.01f;
         }
     }
 
-    static bool was_low = false;
-    if (is_low && !was_low)
-    {
-        LL_WARNS() << "Low system memory detected, emergency downrezzing off screen textures" << LL_ENDL;
-        sDesiredDiscardBias = llmax(sDesiredDiscardBias, 1.5f);
-
-        for (auto& image : gTextureList)
-        {
-            gTextureList.updateImageDecodePriority(image, false /*will modify gTextureList otherwise!*/);
-        }
-    }
-
-    was_low = is_low;
-
-
     // set to max discard bias if the window has been backgrounded for a while
     static bool was_backgrounded = false;
     static LLFrameTimer backgrounded_timer;
@@ -1545,6 +1553,17 @@ void LLViewerFetchedTexture::postCreateTexture()
 
     setActive();
 
+    // rebuild any volumes that are using this texture for sculpts in case their LoD has changed
+    for (U32 i = 0; i < mNumVolumes[LLRender::SCULPT_TEX]; ++i)
+    {
+        LLVOVolume* volume = mVolumeList[LLRender::SCULPT_TEX][i];
+        if (volume)
+        {
+            volume->mSculptChanged = true;
+            gPipeline.markRebuild(volume->mDrawable);
+        }
+    }
+
     if (!needsToSaveRawImage())
     {
         mNeedsAux = false;
@@ -2639,7 +2658,7 @@ void LLViewerFetchedTexture::destroyRawImage()
     if (mAuxRawImage.notNull() && !needsToSaveRawImage())
     {
         sAuxCount--;
-        mAuxRawImage = NULL;
+        mAuxRawImage = nullptr;
     }
 
     if (mRawImage.notNull())
@@ -2654,7 +2673,7 @@ void LLViewerFetchedTexture::destroyRawImage()
             }
         }
 
-        mRawImage = NULL;
+        mRawImage = nullptr;
 
         mIsRawImageValid = false;
         mRawDiscardLevel = INVALID_DISCARD_LEVEL;
@@ -2766,7 +2785,9 @@ void LLViewerFetchedTexture::readbackRawImage()
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
 
-    if (mGLTexturep.notNull() && mGLTexturep->getTexName() != 0 && mRawImage.isNull())
+    // readback the raw image from vram if the current raw image is null or smaller than the texture
+    if (mGLTexturep.notNull() && mGLTexturep->getTexName() != 0 &&
+        (mRawImage.isNull() || mRawImage->getWidth() < mGLTexturep->getWidth() || mRawImage->getHeight() < mGLTexturep->getHeight() ))
     {
         mRawImage = new LLImageRaw();
         if (!mGLTexturep->readBackRaw(-1, mRawImage, false))