opengl: track state of active and bound textures in context

Add TextureState which is responsible to track the state of
texture binding (and unbinding) and changing the current active
texture unit. This is necessary because all GL calls reset the
internal state without checking what the current state actually
is and this can accumulate to a large amount of overhead.

We also unbound the textures (glBindTexture with 0 as ID) after
every operation which is also a major unneeded overhead which is
fixed by this commit.

Change-Id: I770a6a744c0c41850c576b928f027375962088aa
Reviewed-on: https://gerrit.libreoffice.org/24503
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

7 files changed, 160 insertions, 47 deletions

diff --git a/include/vcl/opengl/OpenGLContext.hxx b/include/vcl/opengl/OpenGLContext.hxx
index 44b8d67fd8d9..723a99404ef8 100644
--- a/include/vcl/opengl/OpenGLContext.hxx
+++ b/include/vcl/opengl/OpenGLContext.hxx
@@ -62,6 +62,7 @@ class OpenGLProgram;
 class OpenGLTexture;
 class SalGraphicsImpl;
 class OpenGLTests;
+class RenderState;
 
 /// Holds the information of our new child window
 struct GLWindow
@@ -166,6 +167,11 @@ public:
     OpenGLProgram*      UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
     void                UseNoProgram();
 
+    std::unique_ptr<RenderState>& state()
+    {
+        return mpRenderState;
+    }
+
     /// Is this GL context the current context ?
     bool isCurrent();
     /// release bound resources from the current context
@@ -249,6 +255,8 @@ private:
     ProgramCollection maPrograms;
     OpenGLProgram* mpCurrentProgram;
 
+    std::unique_ptr<RenderState> mpRenderState;
+
 public:
     vcl::Region maClipRegion;
     int mnPainting;
diff --git a/vcl/inc/opengl/RenderState.hxx b/vcl/inc/opengl/RenderState.hxx
new file mode 100644
index 000000000000..a184f2ebe41b
--- /dev/null
+++ b/vcl/inc/opengl/RenderState.hxx
@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ */
+
+#ifndef INCLUDED_VCL_INC_OPENGL_RENDER_STATE_H
+#define INCLUDED_VCL_INC_OPENGL_RENDER_STATE_H
+
+#include "opengl/TextureState.hxx"
+
+class RenderState
+{
+    TextureState maTexture;
+
+public:
+    RenderState()
+    {}
+
+    TextureState& texture() { return maTexture; }
+};
+
+#endif // INCLUDED_VCL_INC_OPENGL_RENDER_STATE_H
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/inc/opengl/TextureState.hxx b/vcl/inc/opengl/TextureState.hxx
new file mode 100644
index 000000000000..945b3b4a95d3
--- /dev/null
+++ b/vcl/inc/opengl/TextureState.hxx
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ */
+
+#ifndef INCLUDED_VCL_INC_OPENGL_TEXTURE_STATE_H
+#define INCLUDED_VCL_INC_OPENGL_TEXTURE_STATE_H
+
+#include <vcl/opengl/OpenGLHelper.hxx>
+
+class TextureState
+{
+private:
+    GLuint mnCurrentTextureUnit;
+    std::vector<GLuint> maBoundTextures;
+
+public:
+    TextureState()
+        : mnCurrentTextureUnit(0)
+        , maBoundTextures(4, 0)
+    {}
+
+    void generate(GLuint& nTexture)
+    {
+        glGenTextures(1, &nTexture);
+        CHECK_GL_ERROR();
+    }
+
+    void active(GLuint nTextureUnit)
+    {
+        if (mnCurrentTextureUnit != nTextureUnit)
+        {
+            glActiveTexture(GL_TEXTURE0 + nTextureUnit);
+            CHECK_GL_ERROR();
+            mnCurrentTextureUnit = nTextureUnit;
+        }
+
+    }
+
+    void bind(GLuint nTexture)
+    {
+        if (maBoundTextures[mnCurrentTextureUnit] != nTexture)
+        {
+            glBindTexture(GL_TEXTURE_2D, nTexture);
+            CHECK_GL_ERROR();
+            maBoundTextures[mnCurrentTextureUnit] = nTexture;
+        }
+    }
+
+    void unbindAndDelete(GLuint nTexture)
+    {
+        unbind(nTexture);
+        glDeleteTextures(1, &nTexture);
+    }
+
+    void unbind(GLuint nTexture)
+    {
+        for (size_t i = 0; i < maBoundTextures.size(); i++)
+        {
+            if (nTexture == maBoundTextures[i])
+                maBoundTextures[i] = 0;
+        }
+    }
+
+};
+
+
+
+#endif // INCLUDED_VCL_INC_OPENGL_TEXTURE_STATE_H
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/opengl/program.cxx b/vcl/opengl/program.cxx
index c8b0583f56a2..c4f5c0e5ec02 100644
--- a/vcl/opengl/program.cxx
+++ b/vcl/opengl/program.cxx
@@ -7,9 +7,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-#include <opengl/program.hxx>
+#include "opengl/program.hxx"
+#include "opengl/RenderState.hxx"
 
 #include <vcl/opengl/OpenGLHelper.hxx>
+#include <vcl/opengl/OpenGLContext.hxx>
 
 #include <glm/glm.hpp>
 #include <glm/gtc/type_ptr.hpp>
@@ -62,19 +64,11 @@ bool OpenGLProgram::Use()
 bool OpenGLProgram::Clean()
 {
     // unbind all textures
-    if( !maTextures.empty() )
+    for (OpenGLTexture& rTexture : maTextures)
     {
-        int nIndex( maTextures.size() - 1 );
-        TextureList::reverse_iterator it( maTextures.rbegin() );
-        while( it != maTextures.rend() )
-        {
-            glActiveTexture( GL_TEXTURE0 + nIndex-- );
-            CHECK_GL_ERROR();
-            it->Unbind();
-            ++it;
-        }
-        maTextures.clear();
+        rTexture.Unbind();
     }
+    maTextures.clear();
 
     // disable any enabled vertex attrib array
     if( mnEnabledAttribs )
@@ -252,10 +246,12 @@ void OpenGLProgram::SetTexture( const OString& rName, OpenGLTexture& rTexture )
 
     glUniform1i( nUniform, nIndex );
     CHECK_GL_ERROR();
-    glActiveTexture( GL_TEXTURE0 + nIndex );
-    CHECK_GL_ERROR();
+
+    std::unique_ptr<RenderState>& rState = OpenGLContext::getVCLContext()->state();
+    rState->texture().active(nIndex);
+
     rTexture.Bind();
-    maTextures.push_back( rTexture );
+    maTextures.push_back(rTexture);
 }
 
 void OpenGLProgram::SetTransform(
diff --git a/vcl/opengl/texture.cxx b/vcl/opengl/texture.cxx
index 232b2cd002f0..e9fca75befa1 100644
--- a/vcl/opengl/texture.cxx
+++ b/vcl/opengl/texture.cxx
@@ -29,6 +29,8 @@
 #include "opengl/framebuffer.hxx"
 #include "opengl/texture.hxx"
 #include "opengl/zone.hxx"
+#include "opengl/RenderState.hxx"
+
 namespace
 {
 
@@ -47,10 +49,11 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nWidth, int nHeight, bool bAllocate )
 {
     OpenGLVCLContextZone aContextZone;
 
-    glGenTextures( 1, &mnTexture );
-    CHECK_GL_ERROR();
-    glBindTexture( GL_TEXTURE_2D, mnTexture );
-    CHECK_GL_ERROR();
+    auto& rState = OpenGLContext::getVCLContext()->state();
+    rState->texture().generate(mnTexture);
+    rState->texture().active(0);
+    rState->texture().bind(mnTexture);
+
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
     CHECK_GL_ERROR();
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
@@ -64,8 +67,6 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nWidth, int nHeight, bool bAllocate )
         glTexImage2D( GL_TEXTURE_2D, 0, constInternalFormat, nWidth, nHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr );
         CHECK_GL_ERROR();
     }
-    glBindTexture( GL_TEXTURE_2D, 0 );
-    CHECK_GL_ERROR();
 
     VCL_GL_INFO( "OpenGLTexture " << mnTexture << " " << nWidth << "x" << nHeight << " allocate" );
 }
@@ -84,10 +85,11 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nX, int nY, int nWidth, int nHeight )
     // FIXME We need the window height here
     // nY = GetHeight() - nHeight - nY;
 
-    glGenTextures( 1, &mnTexture );
-    CHECK_GL_ERROR();
-    glBindTexture( GL_TEXTURE_2D, mnTexture );
-    CHECK_GL_ERROR();
+    auto& rState = OpenGLContext::getVCLContext()->state();
+    rState->texture().generate(mnTexture);
+    rState->texture().active(0);
+    rState->texture().bind(mnTexture);
+
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
     CHECK_GL_ERROR();
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
@@ -98,8 +100,6 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nX, int nY, int nWidth, int nHeight )
     CHECK_GL_ERROR();
     glCopyTexImage2D( GL_TEXTURE_2D, 0, constInternalFormat, nX, nY, nWidth, nHeight, 0 );
     CHECK_GL_ERROR();
-    glBindTexture( GL_TEXTURE_2D, 0 );
-    CHECK_GL_ERROR();
 
     VCL_GL_INFO( "OpenGLTexture " << mnTexture << " " << nWidth << "x" << nHeight << " from x" << nX << ", y" << nY );
 }
@@ -115,10 +115,11 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nWidth, int nHeight, int nFormat, int
 {
     OpenGLVCLContextZone aContextZone;
 
-    glGenTextures( 1, &mnTexture );
-    CHECK_GL_ERROR();
-    glBindTexture( GL_TEXTURE_2D, mnTexture );
-    CHECK_GL_ERROR();
+    auto& rState = OpenGLContext::getVCLContext()->state();
+    rState->texture().generate(mnTexture);
+    rState->texture().active(0);
+    rState->texture().bind(mnTexture);
+
     glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
     CHECK_GL_ERROR();
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
@@ -131,8 +132,6 @@ ImplOpenGLTexture::ImplOpenGLTexture( int nWidth, int nHeight, int nFormat, int
     CHECK_GL_ERROR();
     glTexImage2D( GL_TEXTURE_2D, 0, constInternalFormat, mnWidth, mnHeight, 0, nFormat, nType, pData );
     CHECK_GL_ERROR();
-    glBindTexture( GL_TEXTURE_2D, 0 );
-    CHECK_GL_ERROR();
 
     VCL_GL_INFO( "OpenGLTexture " << mnTexture << " " << nWidth << "x" << nHeight << " from data" );
 }
@@ -187,8 +186,8 @@ void ImplOpenGLTexture::Dispose()
                 glDeleteRenderbuffers( 1, &mnOptStencil );
                 mnOptStencil = 0;
             }
-            glDeleteTextures( 1, &mnTexture );
-
+            auto& rState = pContext->state();
+            rState->texture().unbindAndDelete(mnTexture);
             mnTexture = 0;
         }
         else
@@ -203,14 +202,15 @@ bool ImplOpenGLTexture::InsertBuffer(int nX, int nY, int nWidth, int nHeight, in
 {
     if (!pData || mnTexture == 0)
         return false;
-    glBindTexture(GL_TEXTURE_2D, mnTexture);
-    CHECK_GL_ERROR();
+
+    rtl::Reference<OpenGLContext> xContext = OpenGLContext::getVCLContext();
+    xContext->state()->texture().active(0);
+    xContext->state()->texture().bind(mnTexture);
+
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
     CHECK_GL_ERROR();
     glTexSubImage2D(GL_TEXTURE_2D, 0, nX, mnHeight - nY - nHeight, nWidth, nHeight, nFormat, nType, pData);
     CHECK_GL_ERROR();
-    glBindTexture(GL_TEXTURE_2D, 0);
-    CHECK_GL_ERROR();
 
     VCL_GL_INFO( "OpenGLTexture " << mnTexture << " Insert buff. to " << nX << " " << nY
                                              << " size " << nWidth << "x" << nHeight << " from data" );
@@ -492,10 +492,10 @@ void OpenGLTexture::SetFilter( GLenum nFilter )
 
 void OpenGLTexture::Bind()
 {
-    if( mpImpl )
+    if (mpImpl)
     {
-        glBindTexture( GL_TEXTURE_2D, mpImpl->mnTexture );
-        CHECK_GL_ERROR();
+        std::unique_ptr<RenderState>& rState = OpenGLContext::getVCLContext()->state();
+        rState->texture().bind(mpImpl->mnTexture);
     }
     else
         VCL_GL_INFO( "OpenGLTexture::Binding invalid texture" );
@@ -505,10 +505,10 @@ void OpenGLTexture::Bind()
 
 void OpenGLTexture::Unbind()
 {
-    if( mpImpl )
+    if (mpImpl)
     {
-        glBindTexture( GL_TEXTURE_2D, 0 );
-        CHECK_GL_ERROR();
+        std::unique_ptr<RenderState>& rState = OpenGLContext::getVCLContext()->state();
+        rState->texture().unbind(mpImpl->mnTexture);
     }
 }
 
diff --git a/vcl/opengl/x11/gdiimpl.cxx b/vcl/opengl/x11/gdiimpl.cxx
index fc49e2520e58..61dba9b78db3 100644
--- a/vcl/opengl/x11/gdiimpl.cxx
+++ b/vcl/opengl/x11/gdiimpl.cxx
@@ -22,6 +22,7 @@
 #include <opengl/texture.hxx>
 #include <opengl/x11/gdiimpl.hxx>
 #include <opengl/x11/salvd.hxx>
+#include "opengl/RenderState.hxx"
 
 #include <vcl/opengl/OpenGLContext.hxx>
 #include <vcl/opengl/OpenGLHelper.hxx>
@@ -144,8 +145,8 @@ bool X11OpenGLSalGraphicsImpl::RenderPixmap(X11Pixmap* pPixmap, X11Pixmap* pMask
 
     rCombo.mpTexture.reset(new OpenGLTexture(pPixmap->GetWidth(), pPixmap->GetHeight(), false));
 
-    glActiveTexture( GL_TEXTURE0 );
-    CHECK_GL_ERROR();
+    mpContext->state()->texture().active(0);
+
     rCombo.mpTexture->Bind();
     glXBindTexImageEXT( pDisplay, pGlxPixmap, GLX_FRONT_LEFT_EXT, nullptr );
     rCombo.mpTexture->Unbind();
diff --git a/vcl/source/opengl/OpenGLContext.cxx b/vcl/source/opengl/OpenGLContext.cxx
index 2b1e6bead8cd..b5881fe18c90 100644
--- a/vcl/source/opengl/OpenGLContext.cxx
+++ b/vcl/source/opengl/OpenGLContext.cxx
@@ -41,6 +41,8 @@
 #include <opengl/texture.hxx>
 #include <opengl/zone.hxx>
 
+#include "opengl/RenderState.hxx"
+
 using namespace com::sun::star;
 
 #define MAX_FRAMEBUFFER_COUNT 30
@@ -74,6 +76,7 @@ OpenGLContext::OpenGLContext():
     mpFirstFramebuffer(nullptr),
     mpLastFramebuffer(nullptr),
     mpCurrentProgram(nullptr),
+    mpRenderState(new RenderState),
     mnPainting(0),
     mpPrevContext(nullptr),
     mpNextContext(nullptr)