每帧更新bufferarray OpenTK答案

【问题标题】：Updating bufferarray every frame OpenTK每帧更新bufferarray OpenTK
【发布时间】：2020-09-02 13:27:38
【问题描述】：

我正在 OpenTK 中绘制一个在每一帧中不断改变位置的对象。目前，我通过调用GL.BufferData 不断更改位置数组并缓冲新数据。有没有一种方法可以更新或映射到一个缓冲区数组，而无需在每一帧中创建一个新数组？我注意到我最终得到了Out Of Memory 异常。

private void Drawobject(Vector3 cursorPos)
{           
    float[] cursors = new float[] { cursorPos.X-0.01f , cursorPos.Y-0.01f - 0.2f, cursorPos.Z, cursorPos.X-0.01f, cursorPos.Y-0.01f + 0.2f, cursorPos.Z, cursorPos.X-0.01f - 0.2f, cursorPos.Y-0.01f, cursorPos.Z, cursorPos.X-0.01f + 0.2f, cursorPos.Y-0.01f, cursorPos.Z };
    int VertexBufferCursor, _vao;
    VertexBufferCursor = GL.GenBuffer();
    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferCursor);
    GL.BufferData(BufferTarget.ArrayBuffer, cursors.Count() * sizeof(float), cursors, BufferUsageHint.StaticDraw);
    _vao = GL.GenVertexArray();
    GL.BindVertexArray(_vao);
    GL.EnableVertexAttribArray(0);
    GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 3 * sizeof(float), 0);
    GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
    GL.BindVertexArray(0);
    shader4.Use();
    GL.BindVertexArray(_vao);
    GL.DrawArrays(PrimitiveType.Lines, 0, 4);
    GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
    GL.BindVertexArray(0);
}

protected override void OnRenderFrame(FrameEventArgs e)
{
    Drawobject(currentMousePos);
}

【问题讨论】：

标签： c# opengl vbo opentk vao

【解决方案1】：

在初始化时创建一次Vertex Array Object 和Vertex Buffer Object：

private int VertexBufferCursor;
private int _vao;

private void Init(Vector3 cursorPos)
{           
    float[] cursors = new float[] { cursorPos.X-0.01f , cursorPos.Y-0.01f - 0.2f, cursorPos.Z, cursorPos.X-0.01f, cursorPos.Y-0.01f + 0.2f, cursorPos.Z, cursorPos.X-0.01f - 0.2f, cursorPos.Y-0.01f, cursorPos.Z, cursorPos.X-0.01f + 0.2f, cursorPos.Y-0.01f, cursorPos.Z };
    VertexBufferCursor = GL.GenBuffer();
    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferCursor);
    GL.BufferData(BufferTarget.ArrayBuffer, cursors.Count() * sizeof(float), cursors, BufferUsageHint.StaticDraw);
    _vao = GL.GenVertexArray();
    GL.BindVertexArray(_vao);
    GL.EnableVertexAttribArray(0);
    GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 3 * sizeof(float), 0);
    GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
    GL.BindVertexArray(0);
    GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
}

通过glBufferSubData更新每一帧的缓冲区：

private void Drawobject(Vector3 cursorPos)
{           
    float[] cursors = new float[] { cursorPos.X-0.01f , cursorPos.Y-0.01f - 0.2f, cursorPos.Z, cursorPos.X-0.01f, cursorPos.Y-0.01f + 0.2f, cursorPos.Z, cursorPos.X-0.01f - 0.2f, cursorPos.Y-0.01f, cursorPos.Z, cursorPos.X-0.01f + 0.2f, cursorPos.Y-0.01f, cursorPos.Z };

    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferCursor);
    GL.BufferSubData(BufferTarget.ArrayBuffer, IntPtr.Zero, cursors.Count() * sizeof(float), cursors);
    GL.BindBuffer(BufferTarget.ArrayBuffer, 0);

    shader4.Use();
    GL.BindVertexArray(_vao);
    GL.DrawArrays(PrimitiveType.Lines, 0, 4);
    GL.BindVertexArray(0);
}

【讨论】：