UniformBuffer: wraps around the GL calls needed to have a UBO

Will be used by the RenderShaderData internally to map the CPU side buffer to
the GPU side Uniform Buffer Object.

Change-Id: I6b8ffdbff49d806bb8668df81ec59872feafe611
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/render/io/uniformbuffer.cpp b/src/render/io/uniformbuffer.cpp
new file mode 100644
index 000000000..b41b44f1a
--- /dev/null
+++ b/src/render/io/uniformbuffer.cpp
@@ -0,0 +1,96 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "uniformbuffer_p.h"
+#include <private/qgraphicscontext_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+namespace Render {
+
+UniformBuffer::UniformBuffer()
+    : m_bufferId(-1)
+    , m_isCreated(false)
+{
+}
+
+void UniformBuffer::create(QGraphicsContext *ctx)
+{
+    ctx->openGLContext()->functions()->glGenBuffers(1, &m_bufferId);
+    m_isCreated = true;
+}
+
+void UniformBuffer::destroy(QGraphicsContext *ctx)
+{
+    ctx->openGLContext()->functions()->glDeleteBuffers(1, &m_bufferId);
+    m_isCreated = false;
+}
+
+void UniformBuffer::allocate(QGraphicsContext *ctx, uint size, bool dynamic)
+{
+    ctx->openGLContext()->functions()->glBindBuffer(GL_UNIFORM_BUFFER, m_bufferId);
+    // Either GL_STATIC_DRAW OR GL_DYNAMIC_DRAW depending on  the use case
+    // TO DO: find a way to know how a buffer/QShaderData will be used to use the right usage
+    ctx->openGLContext()->functions()->glBufferData(GL_UNIFORM_BUFFER, size, NULL, dynamic ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
+    ctx->openGLContext()->functions()->glBindBuffer(GL_UNIFORM_BUFFER, 0);
+}
+
+void UniformBuffer::update(QGraphicsContext *ctx, const void *data, uint size)
+{
+    ctx->openGLContext()->functions()->glBindBuffer(GL_UNIFORM_BUFFER, m_bufferId);
+    // TO DO: At the moment, replaces the whole buffer,
+    // look at updating only the parts that have change
+    ctx->openGLContext()->functions()->glBufferSubData(GL_UNIFORM_BUFFER, 0, size, data);
+    ctx->openGLContext()->functions()->glBindBuffer(GL_UNIFORM_BUFFER, 0);
+}
+
+void UniformBuffer::bindToUniformBlock(QGraphicsContext *ctx, int bindingPoint)
+{
+    ctx->bindBufferBase(GL_UNIFORM_BUFFER, bindingPoint, m_bufferId);
+}
+
+} // Render
+
+} // Qt3D
+
+QT_END_NAMESPACE