/// <summary>
/// 将VBO上传到GPU后，就得到VBO的指针。CPU内存中的VBO数据就可以释放掉了。
/// VBO's pointer got from Buffer's GetBufferPtr() method. It's totally OK to free memory of unmanaged array stored in this buffer object now.
/// </summary>
/// <param name="bufferId">用glGenBuffers()得到的VBO的Id。<para>Id got from glGenBuffers();</para></param>
/// <param name="length">此VBO含有多个个元素？<para>How many elements?</para></param>
/// <param name="byteLength">此VBO中的数据在内存中占用多少个字节？<para>How many bytes in this buffer?</para></param>
internal BufferPtr(uint bufferId, int length, int byteLength)
{
if (glBindBuffer == null)
{
glBindBuffer = OpenGL.GetDelegateFor <OpenGL.glBindBuffer>();
glDeleteBuffers = OpenGL.GetDelegateFor <OpenGL.glDeleteBuffers>();
glMapBuffer = OpenGL.GetDelegateFor <OpenGL.glMapBuffer>();
glMapBufferRange = OpenGL.GetDelegateFor <OpenGL.glMapBufferRange>();
glUnmapBuffer = OpenGL.GetDelegateFor <OpenGL.glUnmapBuffer>();
}
this.BufferId = bufferId;
this.Length = length;
this.ByteLength = byteLength;
}
/// <summary>
/// Start to read/write buffer.
/// </summary>
/// <param name="offset"></param>
/// <param name="length"></param>
/// <param name="access"></param>
/// <param name="bind"></param>
/// <returns></returns>
public virtual IntPtr MapBufferRange(int offset, int length, MapBufferRangeAccess access, bool bind = true)
{
if (bind)
{
if (glBindBuffer == null)
{
glBindBuffer = OpenGL.GetDelegateFor <OpenGL.glBindBuffer>();
}
glBindBuffer((uint)this.Target, this.BufferId);
}
if (glMapBufferRange == null)
{
glMapBufferRange = OpenGL.GetDelegateFor <OpenGL.glMapBufferRange>();
}
IntPtr pointer = glMapBufferRange((uint)this.Target, offset, length, (uint)access);
return(pointer);
}
/// <summary>
/// Start to read/write buffer.
/// </summary>
/// <param name="offset"></param>
/// <param name="length"></param>
/// <param name="access"></param>
/// <param name="bind"></param>
/// <returns></returns>
public virtual IntPtr MapBufferRange(int offset, int length, MapBufferRangeAccess access, bool bind = true)
{
if (bind)
{
if (glBindBuffer == null) { glBindBuffer = OpenGL.GetDelegateFor<OpenGL.glBindBuffer>(); }
glBindBuffer((uint)this.Target, this.BufferId);
}
if (glMapBufferRange == null) { glMapBufferRange = OpenGL.GetDelegateFor<OpenGL.glMapBufferRange>(); }
IntPtr pointer = glMapBufferRange((uint)this.Target, offset, length, (uint)access);
return pointer;
}