////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2011, Computer Graphics Group RWTH Aachen University         //
// All rights reserved.                                                       //
////////////////////////////////////////////////////////////////////////////////

#ifndef ACGL_OPENGL_OBJECTS_ELEMENTBUFFERDATA_HH
#define ACGL_OPENGL_OBJECTS_ELEMENTBUFFERDATA_HH

/**
 * An ElementArrayBuffer is an index into ArrayBuffers and defines which
 * elements of that array should be drawn in which order.
 *
 * The combination of (multiple) attributes of (multiple) ArrayBuffers
 * and one (optional) ElementArrayBuffer is a VertexBufferObject or VertexArrayObject.
 *
 * Note: In some documents ElementArrayBuffer are called VertexBufferObjects, VBOs
 *       or IndexBufferObjects (IBOs). But ArrayBuffers can also be called VBOs...
 *       The original extension that introduced these two new buffer types was called
 *       ARB_vertex_buffer_object but the buffers itself are called ArrayBuffer and
 *       ElementArrayBuffer.
 */

#include <ACGL/ACGL.hh>

#include <ACGL/Base/Macros.hh>
#include <ACGL/OpenGL/GL.hh>
#include <ACGL/OpenGL/Tools.hh>
#include <ACGL/OpenGL/Objects/Buffer.hh>


namespace ACGL{
namespace OpenGL{

class ElementArrayBuffer : public Buffer
{
    // ========================================================================================================= \/
    // ============================================================================================ CONSTRUCTORS \/
    // ========================================================================================================= \/
public:
    ElementArrayBuffer( GLenum _type = GL_UNSIGNED_INT)
        : Buffer(GL_ELEMENT_ARRAY_BUFFER), mType(_type)
    {}

    ElementArrayBuffer( SharedBufferObject _pBuffer, GLenum _type  = GL_UNSIGNED_INT)
         : Buffer(_pBuffer, GL_ELEMENT_ARRAY_BUFFER), mType(_type)
    {}

    // ==================================================================================================== \/
    // ============================================================================================ GETTERS \/
    // ==================================================================================================== \/
public:
    inline GLenum getType(void) const { return mType; }

    // ==================================================================================================== \/
    // ============================================================================================ SETTERS \/
    // ==================================================================================================== \/
public:
    //! _type has to be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, GL_UNSIGNED_INT and indicates the
    //! datatype of the indices
    inline void setType (GLenum _type) { mType = _type; }

    //! Returns the number of indices:
    GLuint getElements() {
        return (GLuint)( getSize() / getGLTypeSize(mType));
    }

    //! Overloaded from the base class to _prevent_ redefining of the binding target! (see Buffer)
    inline void setTarget( GLenum ) {
        ACGL::Utils::error() << "DON'T redefine the target binding point of an ElementArrayBuffer" << std::endl;
    }

    // =================================================================================================== \/
    // ============================================================================================ FIELDS \/
    // =================================================================================================== \/
protected:
    //! index data type: GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, GL_UNSIGNED_INT
    GLenum mType;
};

ACGL_SMARTPOINTER_TYPEDEFS(ElementArrayBuffer)


} // OpenGL
} // ACGL

#endif // ACGL_OPENGL_OBJECTS_ELEMENTBUFFERDATA_HH