2 files changed, 16 insertions, 2 deletions
diff --git a/indra/llrender/llrendertarget.cpp b/indra/llrender/llrendertarget.cpp
index 38bc5ff331..c72f8fa2ba 100644
--- a/indra/llrender/llrendertarget.cpp
+++ b/indra/llrender/llrendertarget.cpp
@@ -51,6 +51,7 @@ void check_framebuffer_status()
 }
 
 bool LLRenderTarget::sUseFBO = false;
+bool LLRenderTarget::sClearOnInvalidate = false;
 U32 LLRenderTarget::sCurFBO = 0;
 
 
@@ -473,6 +474,13 @@ void LLRenderTarget::clear(U32 mask_in)
     }
 }
 
+void LLRenderTarget::invalidate(U32 mask_in)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
+    if (!sClearOnInvalidate) { return; }
+    clear(mask_in);
+}
+
 U32 LLRenderTarget::getTexture(U32 attachment) const
 {
     if (attachment >= mTex.size())
@@ -584,7 +592,6 @@ void LLRenderTarget::swapFBORefs(LLRenderTarget& other)
     llassert(!other.isBoundInStack());
 
     // Must be same type
-    llassert(sUseFBO == other.sUseFBO);
     llassert(mResX == other.mResX);
     llassert(mResY == other.mResY);
     llassert(mInternalFormat == other.mInternalFormat);
diff --git a/indra/llrender/llrendertarget.h b/indra/llrender/llrendertarget.h
index cd3290cf66..f066534cf4 100644
--- a/indra/llrender/llrendertarget.h
+++ b/indra/llrender/llrendertarget.h
@@ -63,6 +63,7 @@ class LLRenderTarget
 public:
     // Whether or not to use FBO implementation
     static bool sUseFBO;
+    static bool sClearOnInvalidate;
     static U32 sBytesAllocated;
     static U32 sCurFBO;
     static U32 sCurResX;
@@ -128,11 +129,17 @@ public:
     //  Asserts that this target is not currently bound in the stack
     void bindTarget();
 
-    //clear render targer, clears depth buffer if present,
+    //clear render target, clears depth buffer if present,
     //uses scissor rect if in copy-to-texture mode
     // asserts that this target is currently bound
     void clear(U32 mask = 0xFFFFFFFF);
 
+    //same as clear, except may be a no-op depending on configuration
+    //useful to indicate the buffer is about to be overwritten and we
+    //don't care about its previous contents
+    //depending on the GPU, one may be more expensive than the other
+    void invalidate(U32 mask = 0xFFFFFFFF);
+
     //get applied viewport
     void getViewport(S32* viewport);