Removed PBO texture upload from QGLContextPrivate::bindTexture().

The PBO code path causes a crash on certain AMD graphics cards, plus
seems to perform worse than the straight forward glTexImage2D code path
on several configurations.

Task-number: 257353
Reviewed-by: Gunnar Sletta

2 files changed, 4 insertions, 41 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index e031fb5..af807dd 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -1302,7 +1302,6 @@ void QGLContextPrivate::init(QPaintDevice *dev, const QGLFormat &format)
 #if defined(QT_OPENGL_ES)
     eglContext = 0;
 #endif
-    pbo = 0;
     fbo = 0;
     crWin = false;
     initDone = false;
@@ -1646,12 +1645,6 @@ QGLContext::~QGLContext()
 
 void QGLContextPrivate::cleanup()
 {
-    Q_Q(QGLContext);
-    if (pbo) {
-        QGLContext *ctx = q;
-        glDeleteBuffers(1, &pbo);
-        pbo = 0;
-    }
 }
 
 typedef QHash<QString, GLuint> QGLDDSCache;
@@ -1915,14 +1908,6 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
 
     QGLContext *ctx = q;
 
-    bool use_pbo = false;
-    if (QGLExtensions::glExtensions & QGLExtensions::PixelBufferObject) {
-
-        use_pbo = qt_resolve_buffer_extensions(ctx);
-        if (use_pbo && pbo == 0)
-            glGenBuffers(1, &pbo);
-    }
-
     // the GL_BGRA format is only present in GL version >= 1.2
     GLenum texture_format = (QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_1_2)
                             ? GL_BGRA : GL_RGBA;
@@ -1957,20 +1942,10 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
         glTexParameterf(target, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
 #endif
         glTexParameterf(target, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-
-        // Mipmap generation causes huge slowdown with PBO's for some reason
-        use_pbo = false;
     } else {
         glTexParameterf(target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     }
 
-    uchar *ptr = 0;
-    if (use_pbo) {
-        glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
-        glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, img.width() * img.height() * 4, 0, GL_STREAM_DRAW_ARB);
-        ptr = reinterpret_cast<uchar *>(glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY_ARB));
-    }
-
     QImage::Format target_format = img.format();
     // Note: the clean param is only true when a texture is bound
     // from the QOpenGLPaintEngine - in that case we have to force
@@ -1980,21 +1955,10 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
     if (img.format() != target_format)
         img = img.convertToFormat(target_format);
 
-    if (ptr) {
-        QImage buffer(ptr, img.width(), img.height(), target_format);
-        convertToGLFormatHelper(buffer, img, texture_format);
-        glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
-        glTexImage2D(target, 0, format, img.width(), img.height(), 0, texture_format,
-                     GL_UNSIGNED_BYTE, 0);
-    } else {
-        QImage tx(scale ? QSize(tx_w, tx_h) : img.size(), target_format);
-        convertToGLFormatHelper(tx, img, texture_format);
-        glTexImage2D(target, 0, format, tx.width(), tx.height(), 0, texture_format,
-                     GL_UNSIGNED_BYTE, tx.bits());
-    }
-
-    if (use_pbo)
-        glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+    QImage tx(scale ? QSize(tx_w, tx_h) : img.size(), target_format);
+    convertToGLFormatHelper(tx, img, texture_format);
+    glTexImage2D(target, 0, format, tx.width(), tx.height(), 0, texture_format,
+                 GL_UNSIGNED_BYTE, tx.bits());
 
     // this assumes the size of a texture is always smaller than the max cache size
     int cost = img.width()*img.height()*4/1024;
diff --git a/src/opengl/qgl_p.h b/src/opengl/qgl_p.h
index 92aea6c..ab040ed 100644
--- a/src/opengl/qgl_p.h
+++ b/src/opengl/qgl_p.h
@@ -252,7 +252,6 @@ public:
 #endif
     QGLFormat glFormat;
     QGLFormat reqFormat;
-    GLuint pbo;
     GLuint fbo;
 
     uint valid : 1;