OpenSceneGraph/include/osg/BufferIndexBinding
Robert Osfield e5a9eaa711 From Tim Moore, "Here is initial support for uniform buffer objects. The binding between a buffer object and an indexed target is implemented as a new StateAttribute, UniformBufferBinding. I've included an example program based on the code in the ARB_uniform_buffer_object specification.
A few things remain to do:
* The binding between a uniform block in a shader program and a buffer indexed target number is fixed, like a vertex attribute binding. This is too restrictive because that binding can be changed without relinking the program. This mapping should be done by name in the same way that uniform values are handled i.e., like a pseudo state attribute;

* There's no direct way yet to query for the offset of uniforms in uniform block, so only the std140 layout is really usable. A helper class that implemented the std140 rules would be quite helpful for setting up uniform blocks without having to link a program first;

* There's no direct support for querying parameters such as the maximum block length, minimum offset alignment, etc. Having that information available outside of the draw thread would make certain instancing techniques easier to implement."
2010-11-29 17:43:27 +00:00

130 lines
4.8 KiB
C++

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
* Copyright (C) 2010 Tim Moore
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* OpenSceneGraph Public License for more details.
*/
#ifndef OSG_BUFFERINDEXBINDING
#define OSG_BUFFERINDEXBINDING 1
#include <osg/Export>
#include <osg/BufferObject>
#include <osg/StateAttribute>
namespace osg {
class State;
/** Encapsulate binding buffer objects to index targets. This
* specifically supports the uniform buffer and transform feedback
* targets.
*/
// Common implementation superclass
class OSG_EXPORT BufferIndexBinding : public StateAttribute
{
protected:
BufferIndexBinding(GLenum target, GLuint index);
BufferIndexBinding(GLenum target, GLuint index, BufferObject* bo, GLintptr offset,
GLsizeiptr size);
BufferIndexBinding(const BufferIndexBinding& rhs, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
public:
// The member value is part of the key to this state attribute in
// the State class. Using the index target, we can seperately
// track the bindings for many different index targets.
virtual unsigned getMember() const { return static_cast<unsigned int>(_index); }
GLenum getTarget() const { return _target; }
/** Get the index target.
*/
GLuint getIndex() const { return _index; }
/** Set the buffer object that will be bound to the index target.
*/
void setBufferObject(BufferObject *bo) { _bufferObject = bo; }
/** Get the buffer object to be bound.
*/
BufferObject* getBufferObject() const { return _bufferObject.get(); }
/** Set the starting offset into the buffer object for data for
the indexed target. Note: the required alignment on the offset
may be quite large (e.g., 256 bytes on NVidia 8600M). This
should be checked with glGetIntegerv(GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT...).
*/
void setOffset(GLintptr offset) { _offset = offset; }
GLintptr getOffset() const { return _offset; }
/** Set the size of data for the indexed target.
*/
void setSize(GLsizeiptr size) { _size = size; }
GLsizeiptr getSize() const { return _size; }
virtual void apply(State& state) const;
protected:
virtual ~BufferIndexBinding();
const GLenum _target;
const GLuint _index;
ref_ptr<BufferObject> _bufferObject;
GLintptr _offset;
GLsizeiptr _size;
};
/** StateAttribute for binding a uniform buffer index target.
*/
class OSG_EXPORT UniformBufferBinding : public BufferIndexBinding
{
public:
UniformBufferBinding();
UniformBufferBinding(GLuint index);
/** Create a binding for a uniform buffer index target.
* @param index the index target
* @param bo associated buffer object
* @param offset offset into buffer object
* @param size size of data in buffer object
*/
UniformBufferBinding(GLuint index, BufferObject* bo, GLintptr offset, GLsizeiptr size);
UniformBufferBinding(const UniformBufferBinding& rhs, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
META_StateAttribute(osg, UniformBufferBinding, UNIFORMBUFFERBINDING);
virtual int compare(const StateAttribute& bb) const
{
COMPARE_StateAttribute_Types(UniformBufferBinding, bb)
COMPARE_StateAttribute_Parameter(_target)
COMPARE_StateAttribute_Parameter(_index)
COMPARE_StateAttribute_Parameter(_bufferObject)
COMPARE_StateAttribute_Parameter(_offset)
COMPARE_StateAttribute_Parameter(_size)
return 0;
}
};
/** StateAttribute for binding a transform feedback index target.
*/
class OSG_EXPORT TransformFeedbackBufferBinding : public BufferIndexBinding
{
public:
TransformFeedbackBufferBinding(GLuint index = 0);
TransformFeedbackBufferBinding(GLuint index, BufferObject* bo, GLintptr offset, GLsizeiptr size);
TransformFeedbackBufferBinding(const TransformFeedbackBufferBinding& rhs, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
META_StateAttribute(osg, TransformFeedbackBufferBinding, TRANSFORMFEEDBACKBUFFERBINDING);
virtual int compare(const StateAttribute& bb) const
{
COMPARE_StateAttribute_Types(TransformFeedbackBufferBinding, bb)
COMPARE_StateAttribute_Parameter(_target)
COMPARE_StateAttribute_Parameter(_index)
COMPARE_StateAttribute_Parameter(_bufferObject)
COMPARE_StateAttribute_Parameter(_offset)
COMPARE_StateAttribute_Parameter(_size)
return 0;
}
};
}
#endif