StelOpenGLArray.hpp

/*
 * Stellarium
 * Copyright (C) 2016 Florian Schaukowitsch
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335, USA.
 */

#ifndef _STELOPENGLARRAY_HPP_
#define _STELOPENGLARRAY_HPP_

#include "VecMath.hpp"

#include <QLoggingCategory>
#include <QOpenGLBuffer>
#include <QOpenGLFunctions>
#include <QOpenGLVertexArrayObject>
#include <QVector>

class StelOBJ;
class QOpenGLFunctions;

Q_DECLARE_LOGGING_CATEGORY(stelOpenGLArray)

class StelOpenGLArray
{
public:
    enum AttributeLocation
    {
        ATTLOC_VERTEX,
        ATTLOC_TEXCOORD,
        ATTLOC_NORMAL,
        ATTLOC_TANGENT,
        ATTLOC_BITANGENT,
        ATTLOC_SIZE
    };

    StelOpenGLArray();
    ~StelOpenGLArray();

    void clear();

    bool load(const StelOBJ* obj, bool useTangents = true);

    void bind();
    void release();

    inline void draw() const
    {
        draw(0,m_indexCount);
    }
    inline void draw(int offset, int count) const
    {
        gl->glDrawElements(GL_TRIANGLES, count, m_indexBufferType, reinterpret_cast<const GLvoid*>(offset * m_indexBufferTypeSize));
    }

    const QOpenGLBuffer& getVertexBuffer() const { return m_vertexBuffer; }
    const QOpenGLBuffer& getIndexBuffer() const { return m_indexBuffer; }
    const QOpenGLVertexArrayObject& getVAO() const { return m_vao; }

    GLenum getIndexBufferType() const { return m_indexBufferType; }
    size_t getIndexBufferTypeSize() const { return m_indexBufferTypeSize; }
    int getIndexCount() const { return m_indexCount; }

    static void initGL();
    static bool supportsVertexArrayObject() { return s_vaosSupported; }
    static bool supportsIntegerElementIndex() { return s_intElementBuffersSupported; }
private:
    QOpenGLBuffer m_vertexBuffer;
    QOpenGLBuffer m_indexBuffer;
    QOpenGLVertexArrayObject m_vao;
    GLenum m_indexBufferType;
    size_t m_indexBufferTypeSize;
    int m_indexCount;
    size_t m_memoryUsage;

    quintptr m_offsets[ATTLOC_SIZE];
    GLint m_sizes[ATTLOC_SIZE];
    GLenum m_types[ATTLOC_SIZE];
    GLsizei m_strides[ATTLOC_SIZE];

    void bindBuffers();
    void releaseBuffers();

    static QOpenGLFunctions* gl;
    static bool s_vaosSupported;
    static bool s_intElementBuffersSupported;
};

#endif // _STELOPENGLARRAY_HPP_