From 45f42cdea993f3e173588f4254dc432be58c69ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Gr=C3=A4=C3=9Flin?= <kde@martin-graesslin.com>
Date: Sat, 11 Dec 2010 15:52:21 +0100
Subject: [PATCH] Adding a shared VBO for streaming data.

---
 lib/kwinglutils.cpp | 17 +++++++++++++++++
 lib/kwinglutils.h   | 14 +++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/lib/kwinglutils.cpp b/lib/kwinglutils.cpp
index 051026dfaa..ae0ed72453 100644
--- a/lib/kwinglutils.cpp
+++ b/lib/kwinglutils.cpp
@@ -1498,6 +1498,7 @@ class GLVertexBufferPrivate
         int dimension;
         bool useShader;
         static bool supported;
+        static GLVertexBuffer *streamingBuffer;
         QVector<float> legacyVertices;
         QVector<float> legacyTexCoords;
         bool useColor;
@@ -1508,6 +1509,7 @@ class GLVertexBufferPrivate
         void corePainting( const QRegion& region, GLenum primitiveMode );
     };
 bool GLVertexBufferPrivate::supported = false;
+GLVertexBuffer *GLVertexBufferPrivate::streamingBuffer = NULL;
 
 void GLVertexBufferPrivate::legacyPainting( QRegion region, GLenum primitiveMode )
     {
@@ -1721,6 +1723,16 @@ void GLVertexBuffer::setColor(const QColor& color, bool enable)
     d->color = color;
 }
 
+void GLVertexBuffer::reset()
+{
+    d->useColor       = false;
+    d->color          = QColor(0, 0, 0, 255);
+    d->numberVertices = 0;
+    d->dimension      = 2;
+    d->useShader      = false;
+    d->useTexCoords   = true;
+}
+
 void GLVertexBuffer::initStatic()
     {
 #ifdef KWIN_HAVE_OPENGLES
@@ -1728,8 +1740,13 @@ void GLVertexBuffer::initStatic()
 #else
     GLVertexBufferPrivate::supported = hasGLExtension( "GL_ARB_vertex_buffer_object" );
 #endif
+    GLVertexBufferPrivate::streamingBuffer = new GLVertexBuffer(GLVertexBuffer::Stream);
     }
 
+GLVertexBuffer *GLVertexBuffer::streamingBuffer()
+{
+    return GLVertexBufferPrivate::streamingBuffer;
+}
 
 } // namespace
 
diff --git a/lib/kwinglutils.h b/lib/kwinglutils.h
index 8ff045b71d..7e9eebb705 100644
--- a/lib/kwinglutils.h
+++ b/lib/kwinglutils.h
@@ -62,7 +62,6 @@ void KWIN_EXPORT initGL();
 // Initializes EGL function pointers
 void KWIN_EXPORT initEGL();
 
-
 // Number of supported texture units
 extern KWIN_EXPORT int glTextureUnitsCount;
 
@@ -552,6 +551,13 @@ class KWIN_EXPORT GLVertexBuffer
          **/
         void setUseColor(bool enable);
 
+        /**
+         * Resets the instance to default values.
+         * Useful for shared buffers.
+         * @since 4.7
+         **/
+        void reset();
+
         /**
          * @internal
          */
@@ -563,6 +569,12 @@ class KWIN_EXPORT GLVertexBuffer
          */
         static bool isSupported();
 
+        /**
+         * @return A shared VBO for streaming data
+         * @since 4.7
+         **/
+        static GLVertexBuffer *streamingBuffer();
+
     private:
         GLVertexBufferPrivate* const d;
 };