- reset the viewpoint buffer only once per scene, not per viewpoint.

This doesn't work for camera textures because they are a separate viewpoint.

src/gl/renderer/gl_renderer.cpp

@@ -135,6 +135,7 @@ FGLRenderer::~FGLRenderer()
 
 	if (swdrawer) delete swdrawer;
 	if (mBuffers) delete mBuffers;
+	if (mSaveBuffers) delete mSaveBuffers;
 	if (mPresentShader) delete mPresentShader;
 	if (mPresent3dCheckerShader) delete mPresent3dCheckerShader;
 	if (mPresent3dColumnShader) delete mPresent3dColumnShader;
@@ -221,6 +222,7 @@ sector_t *FGLRenderer::RenderView(player_t* player)
 		P_FindParticleSubsectors();
 
 		mLights->Clear();
+		mViewpoints->Clear();
 
 		// NoInterpolateView should have no bearing on camera textures, but needs to be preserved for the main view below.
 		bool saved_niv = NoInterpolateView;
@@ -322,6 +324,7 @@ void FGLRenderer::WriteSavePic (player_t *player, FileWriter *file, int width, i
     gl_RenderState.SetVertexBuffer(mVBO);
     mVBO->Reset();
     mLights->Clear();
+	mViewpoints->Clear();
 
     // This shouldn't overwrite the global viewpoint even for a short time.
     FRenderViewpoint savevp;

src/gl/scene/gl_scene.cpp

@@ -449,7 +449,6 @@ sector_t * FGLRenderer::RenderViewpoint (FRenderViewpoint &mainvp, AActor * came
     // Render (potentially) multiple views for stereo 3d
 	// Fixme. The view offsetting should be done with a static table and not require setup of the entire render state for the mode.
 	auto vrmode = VRMode::GetVRMode(mainview && toscreen);
-	mViewpoints->Clear();
 	for (int eye_ix = 0; eye_ix < vrmode->mEyeCount; ++eye_ix)
 	{
 		const auto &eye = vrmode->mEyes[eye_ix];