BufferObject.SetData

public void SetData(DataType[] source, int sourceIndex = 0, int destIndex = 0, int count = -1)
{
#if !RUNS_WITH_SCISSORS
    if (source == null)
        throw new ArgumentNullException("source");

    if (sourceIndex < 0 || sourceIndex >= source.Length)
        throw new ArgumentOutOfRangeException("sourceIndex",
            "The source index must be greater-than or equal to 0 and less-than the source length.");

    if (destIndex < 0 || destIndex >= m_count)
        throw new ArgumentOutOfRangeException("destIndex",
            "The dest index must be greater-than or equal to 0 and less-than the buffer's count.");
#endif
    if (count == -1)
        count = Math.Min(source.Length - sourceIndex, m_count - destIndex);
#if !RUNS_WITH_SCISSORS
    else if (source.Length - sourceIndex < count)
        throw new ArgumentOutOfRangeException("count",
            "The count specified is larger than the source array.");
    else if (m_count - destIndex < count)
        throw new ArgumentOutOfRangeException("count",
            "The count specified is larger than the buffer's count.");
#endif
    IntPtr offset = new IntPtr(m_stride * destIndex);
    IntPtr size = new IntPtr(m_stride * count);
    int sourceOffset = sourceIndex * m_stride;
    int destOffset = destIndex * m_stride;

    GL.BindBuffer(m_target, m_ID);
#if ES20
    GL.BufferSubData(m_target, offset, size, source);
#else
    IntPtr videoMemory = GL.MapBufferRange(m_target, offset, size, BufferAccessMask.MapWriteBit);
    if (videoMemory == IntPtr.Zero)
    {
        videoMemory = GL.MapBuffer(m_target, BufferAccess.WriteOnly);
        if (videoMemory == IntPtr.Zero)
        {
            throw new InvalidOperationException(
                "Unable to map video memory.", new Exception(GL.GetError().ToString()));
        }
    }
    else
        destOffset = 0; // mapped the range, no need for an offset

    GCHandle dataHandle = GCHandle.Alloc(source, GCHandleType.Pinned);
    IntPtr systemMemory = dataHandle.AddrOfPinnedObject();
    unsafe
    {
        byte* sourcePtr = ((byte*)systemMemory) + sourceOffset;
        byte* destPtr = ((byte*)videoMemory) + destOffset;
        for (int i = 0; i < count * m_stride; i++) destPtr[i] = sourcePtr[i];
    }
    dataHandle.Free();

    GL.UnmapBuffer(m_target);
#endif
    GL.BindBuffer(m_target, 0);

    if (m_shadowCopy)
        Array.Copy(source, sourceIndex, m_data, destIndex, count);
}