MythRenderOpenGL: Remove framebuffer discard support

- this is not working as intended and further digging suggests it is not
appropriate for our prospective use case

mythtv/libs/libmythtv/openglvideo.cpp

@@ -64,15 +64,6 @@ OpenGLVideo::OpenGLVideo(MythRenderOpenGL *Render, VideoColourSpace *ColourSpace
     m_features      = m_render->GetFeatures();
     m_extraFeatures = m_render->GetExtraFeatures();
 
-    // Enable/Disable certain features based on settings
-    if (m_render->isOpenGLES())
-    {
-        if ((m_extraFeatures & kGLExtFBDiscard) && gCoreContext->GetBoolSetting("OpenGLDiscardFB", false))
-            LOG(VB_GENERAL, LOG_INFO, LOC + "Enabling Framebuffer discards");
-        else
-            m_extraFeatures &= ~kGLExtFBDiscard;
-    }
-
     // Create initial input texture. Hardware textures are created on demand.
     MythGLTexture *texture = nullptr;
     if (kGLInterop != m_frameType)
@@ -678,8 +669,6 @@ void OpenGLVideo::PrepareFrame(VideoFrame *Frame, bool TopFieldFirst, FrameScanT
         LOG(VB_PLAYBACK, LOG_INFO, LOC + "Enabled resizing");
     }
 
-    bool discardframebuffer = false;
-
     if (resize)
     {
         // render to texture stage
@@ -729,7 +718,6 @@ void OpenGLVideo::PrepareFrame(VideoFrame *Frame, bool TopFieldFirst, FrameScanT
         inputtextures.clear();
         inputtextures.push_back(m_frameBufferTexture);
         program = Default;
-        discardframebuffer = true;
         deinterlacing = false;
     }
 
@@ -775,14 +763,6 @@ void OpenGLVideo::PrepareFrame(VideoFrame *Frame, bool TopFieldFirst, FrameScanT
     // draw
     m_render->DrawBitmap(textures, numtextures, nullptr, trect, m_displayVideoRect, m_shaders[program]);
 
-    // discard
-    if (m_extraFeatures & kGLExtFBDiscard)
-    {
-        if (discardframebuffer && m_frameBuffer)
-            m_render->DiscardFramebuffer(m_frameBuffer);
-        m_render->DiscardFramebuffer(nullptr);
-    }
-
     if (VERBOSE_LEVEL_CHECK(VB_GPU, LOG_INFO))
         m_render->logDebugMarker(LOC + "PREP_FRAME_END");
 }

mythtv/libs/libmythui/mythrender_opengl.cpp

@@ -142,7 +142,6 @@ MythRenderOpenGL::MythRenderOpenGL(const QSurfaceFormat& Format, QPaintDevice* D
     m_glDeleteFencesAPPLE(nullptr),
     m_glSetFenceAPPLE(nullptr),
     m_glFinishFenceAPPLE(nullptr),
-    m_glDiscardFramebuffer(nullptr),
     m_openglDebugger(nullptr),
     m_window(nullptr)
 {
@@ -289,10 +288,6 @@ bool MythRenderOpenGL::Init(void)
         m_glSetFenceAPPLE  && m_glFinishFenceAPPLE)
         m_extraFeatures |= kGLAppleFence;
 
-    // Framebuffer discard - GLES only
-    if (isOpenGLES() && hasExtension("GL_EXT_discard_framebuffer") && m_glDiscardFramebuffer)
-        m_extraFeatures |= kGLExtFBDiscard;
-
     // Rectangular textures
     if (!isOpenGLES() && (hasExtension("GL_NV_texture_rectangle") ||
                           hasExtension("GL_ARB_texture_rectangle") ||
@@ -345,7 +340,6 @@ void MythRenderOpenGL::DebugFeatures(void)
     LOG(VB_GENERAL, LOG_INFO, LOC + QString("RGBA16 textures      : %1").arg(GLYesNo(m_extraFeatures & kGLExtRGBA16)));
     LOG(VB_GENERAL, LOG_INFO, LOC + QString("Buffer mapping       : %1").arg(GLYesNo(m_extraFeatures & kGLBufferMap)));
     LOG(VB_GENERAL, LOG_INFO, LOC + QString("Framebuffer objects  : %1").arg(GLYesNo(m_features & Framebuffers)));
-    LOG(VB_GENERAL, LOG_INFO, LOC + QString("Framebuffer discard  : %1").arg(GLYesNo(m_extraFeatures & kGLExtFBDiscard)));
     LOG(VB_GENERAL, LOG_INFO, LOC + QString("Fence                : %1")
         .arg(GLYesNo((m_extraFeatures & kGLAppleFence) || (m_extraFeatures & kGLNVFence))));
 
@@ -874,19 +868,6 @@ void MythRenderOpenGL::ClearFramebuffer(void)
     doneCurrent();
 }
 
-void MythRenderOpenGL::DiscardFramebuffer(QOpenGLFramebufferObject *Framebuffer)
-{
-    if (!(m_extraFeaturesUsed & kGLExtFBDiscard))
-        return;
-
-    makeCurrent();
-    static const GLenum fbdiscards[] = { GL_COLOR_ATTACHMENT0 };
-    static const GLenum dfdiscards[] = { GL_COLOR_EXT };
-    BindFramebuffer(Framebuffer);
-    m_glDiscardFramebuffer(GL_FRAMEBUFFER, 1, (Framebuffer ? true : defaultFramebufferObject()) ? fbdiscards : dfdiscards);
-    doneCurrent();
-}
-
 void MythRenderOpenGL::DrawBitmap(MythGLTexture *Texture, QOpenGLFramebufferObject *Target,
                                   const QRect &Source, const QRect &Destination,
                                   QOpenGLShaderProgram *Program, int Alpha,
@@ -1251,7 +1232,6 @@ void MythRenderOpenGL::InitProcs(void)
     m_glDeleteFencesAPPLE = reinterpret_cast<MYTH_GLDELETEFENCESAPPLEPROC>(GetProcAddress("glDeleteFencesAPPLE"));
     m_glSetFenceAPPLE = reinterpret_cast<MYTH_GLSETFENCEAPPLEPROC>(GetProcAddress("glSetFenceAPPLE"));
     m_glFinishFenceAPPLE = reinterpret_cast<MYTH_GLFINISHFENCEAPPLEPROC>(GetProcAddress("glFinishFenceAPPLE"));
-    m_glDiscardFramebuffer = reinterpret_cast<MYTH_GLDISCARDFRAMEBUFFER>(GetProcAddress("glDiscardFramebufferEXT"));
 }
 
 QFunctionPointer MythRenderOpenGL::GetProcAddress(const QString &Proc) const

mythtv/libs/libmythui/mythrender_opengl.h

@@ -29,12 +29,11 @@
 typedef enum
 {
     kGLFeatNone    = 0x0000,
-    kGLExtFBDiscard= 0x0001,
-    kGLNVFence     = 0x0002,
-    kGLAppleFence  = 0x0004,
-    kGLBufferMap   = 0x0008,
-    kGLExtRects    = 0x0010,
-    kGLExtRGBA16   = 0x0020
+    kGLNVFence     = 0x0001,
+    kGLAppleFence  = 0x0002,
+    kGLBufferMap   = 0x0004,
+    kGLExtRects    = 0x0008,
+    kGLExtRGBA16   = 0x0010
 } GLFeatures;
 
 #define TEX_OFFSET 8
@@ -142,7 +141,6 @@ class MUI_PUBLIC MythRenderOpenGL : public QOpenGLContext, public QOpenGLFunctio
     void  DeleteFramebuffer(QOpenGLFramebufferObject *Framebuffer);
     void  BindFramebuffer(QOpenGLFramebufferObject *Framebuffer);
     void  ClearFramebuffer(void);
-    void  DiscardFramebuffer(QOpenGLFramebufferObject *Framebuffer);
 
     QOpenGLShaderProgram* CreateShaderProgram(const QString &Vertex, const QString &Fragment);
     void  DeleteShaderProgram(QOpenGLShaderProgram* Program);
@@ -247,8 +245,6 @@ class MUI_PUBLIC MythRenderOpenGL : public QOpenGLContext, public QOpenGLFunctio
     MYTH_GLDELETEFENCESAPPLEPROC         m_glDeleteFencesAPPLE;
     MYTH_GLSETFENCEAPPLEPROC             m_glSetFenceAPPLE;
     MYTH_GLFINISHFENCEAPPLEPROC          m_glFinishFenceAPPLE;
-    // Framebuffer discard
-    MYTH_GLDISCARDFRAMEBUFFER            m_glDiscardFramebuffer;
 
   private:
     void DebugFeatures (void);

mythtv/programs/mythfrontend/globalsettings.cpp

@@ -130,16 +130,6 @@ static HostCheckBoxSetting *OpenGLExtraStage()
 
     return gc;
 }
-
-static HostCheckBoxSetting *OpenGLDiscardFB()
-{
-    HostCheckBoxSetting *gc = new HostCheckBoxSetting("OpenGLDiscardFB");
-    gc->setLabel(PlaybackSettings::tr("Discard OpenGL Framebuffers"));
-    gc->setHelpText(PlaybackSettings::tr(
-        "Enable to improve performance on some OpenGL ES GPU implementations (e.g. ARM Mali, Qualcomm Adreno) EXPERIMENTAL."));
-    gc->setValue(false);
-    return gc;
-}
 #endif
 
 #if CONFIG_DEBUGTYPE
@@ -4262,17 +4252,7 @@ void PlaybackSettings::Load(void)
     avsync2->addTargetedChild("1",AVSync2AdjustMS());
 
 #ifdef USE_OPENGL_PAINTER
-    bool isOpenGLES = false;
-    MythMainWindow* main = static_cast<MythMainWindow*>(gCoreContext->GetGUIObject());
-    if (main)
-    {
-        MythRenderOpenGL* render = static_cast<MythRenderOpenGL*>(main->GetRenderDevice());
-        if (render)
-            isOpenGLES = render->isOpenGLES();
-    }
     advanced->addChild(OpenGLExtraStage());
-    if (isOpenGLES)
-        advanced->addChild(OpenGLDiscardFB());
 #endif
     addChild(advanced);