如何将 OpenGL 项目从旧的 glVertexAttribPointer 方法转换为新的 glVertexAttribBinding 方法？

Question

我有一个 OpenGL 项目，该项目以前使用基于 OpenGL 3.0 的方法来绘制数组，我正在尝试将其转换为使用更新的方法（至少从 OpenGL 4.3 开始可用）。但是，到目前为止我还没有能够让它发挥作用。

我将用于解释的这段代码创建了点分组并在它们之间画线。它还可以填充生成的多边形（使用三角形）。我将给出一个使用点绘图例程的示例。这是它过去如何工作的伪代码：

[原始]第一次生成点时（发生一次）：

// ORIGINAL, WORKING CODE RUN ONCE DURING SETUP:
    // NOTE: This code is in c# and uses a library called SharpGL
    // to invoke OpenGL calls via a context herein called "gl"

    float[] xyzArray = [CODE NOT SHOWN -- GENERATES ARRAY OF POINTS]

    // Create a buffer for the vertex data
    // METHOD CODE NOT SHOWN, but uses glGenBuffers to fill class-member buffer IDs
    GenerateBuffers(gl);  // Note: we now have a VerticesBufferId

    // Set the vertex buffer as the current buffer and fill it
    gl.BindBuffer(OpenGL.GL_ARRAY_BUFFER, this.VerticesBufferId);
    gl.BufferData(OpenGL.GL_ARRAY_BUFFER, xyzArray, OpenGL.GL_STATIC_DRAW);

[原始]在绘图的循环中：

// ORIGINAL, WORKING CODE EXECUTED DURING EACH DRAW LOOP:
    // NOTE: This code is in c# and uses a library called SharpGL
    // to invoke OpenGL calls via a context herein called "gl"

    // Note: positionAttributeId (below) was derived from the active
    // shader program via glGetAttribLocation 
    gl.BindBuffer(OpenGL.GL_ARRAY_BUFFER, this.VerticesBufferId);
    gl.EnableVertexAttribArray(positionAttributeId);
    gl.VertexAttribPointer(positionAttributeId, 3, OpenGL.GL_FLOAT, false, 0, IntPtr.Zero);
    
    // Missing code sets some uniforms in the shader program and determines
    // the start (iStart) and length (pointCount) of points to draw

    gl.DrawArrays(OpenGL.GL_LINE_STRIP, iStart, pointCount);

该代码现在已经运行了很长一段时间，但我正在尝试转向更现代的技术。我的大部分代码根本没有改变，这是替换上面代码的新代码：

[After Mods] 首次生成点时（发生一次）：

// MODIFIED CODE RUN ONCE DURING SETUP:
    // NOTE: This code is in c# and uses a library called SharpGL
    // to invoke OpenGL calls via a context herein called "gl"

    float[] xyzArray = [CODE NOT SHOWN -- GENERATES ARRAY OF POINTS]

    // Create a buffer for the vertex data
    // METHOD CODE NOT SHOWN, but uses glGenBuffers to fill class-member buffer IDs
    GenerateBuffers(gl);  // Note: we now have a VerticesBufferId.

    // Set the vertex buffer as the current buffer
    gl.BindBuffer(OpenGL.GL_ARRAY_BUFFER, this.VerticesBufferId);
    gl.BufferData(OpenGL.GL_ARRAY_BUFFER, xyzArray, OpenGL.GL_STATIC_DRAW);

// ^^^ ALL CODE ABOVE THIS LINE IS IDENTIAL TO THE ORIGINAL ^^^
    // Generate Vertex Arrays
    // METHOD CODE NOT SHOWN, but uses glGenVertexArrays to fill class-member array IDs
    GenerateVertexArrays(gl);  // Note: we now have a PointsArrayId

    // My understanding: I'm telling OpenGL to associate following calls
    // with the vertex array generated with the ID PointsArrayId...
    gl.BindVertexArray(PointsArrayId);

    // Here I associate the positionAttributeId (found from the shader program)
    // with the currently bound vertex array (right?)
    gl.EnableVertexAttribArray(positionAttributeId);

    // Here I tell the bound vertex array about the format of the position
    // attribute as it relates to that array -- I think.
    gl.VertexAttribFormat(positionAttributeId, 3, OpenGL.GL_FLOAT, false, 0);

    // As I understand it, I can define my own "local" buffer index
    // in the following calls (?).  Below I use 0, which I then bind
    // to the buffer with id = this.VerticesBufferId (for the purposes
    // of the currently bound vertex array)
    gl.VertexAttribBinding(positionAttributeId, 0);
    gl.BindVertexBuffer(0, this.VerticesBufferId, IntPtr.Zero, 0);

    gl.BindVertexArray(0); // we no longer want to be bound to PointsArrayId

[After Mods] 在绘制的循环中：

// MODIFIED CODE EXECUTED DURING EACH DRAW LOOP::
    // NOTE: This code is in c# and uses a library called SharpGL
    // to invoke OpenGL calls via a context herein called "gl"

    // Here I tell OpenGL to bind the VertexArray I established previously
    // (which should understand how to fill the position attribute in the
    // shader program using the "zeroth" buffer index tied to the 
    // VerticesBufferId data buffer -- because I went through all the trouble
    // of telling it that above, right?)
    gl.BindVertexArray(this.PointsArrayId);

    // \/ \/ \/ NOTE: NO CODE CHANGES IN THE CODE BELOW ThIS LINE  \/ \/ \/
    // Missing code sets some uniforms in the shader program and determines
    // the start (iStart) and length (pointCount) of points to draw

    gl.DrawArrays(OpenGL.GL_LINE_STRIP, iStart, pointCount);

修改后，例程没有在屏幕上绘制任何内容。没有抛出异常或指示（我可以告诉）执行命令时出现问题。它只会留下一个空白屏幕。

一般问题：

我转换到较新的顶点数组方法看起来正确吗？你看到逻辑上有什么错误吗？
我是否应该执行特定的 glEnable 调用以使此方法代替旧方法工作？
我可以在同一个着色器程序中混用这两种填充属性的方法吗？（例如，除了上述之外，我还填写了三角形数据并通过相同的着色器程序使用它。如果我没有将该过程切换到新方法，是否会导致问题）？

如果这里还有什么我遗漏的，请告诉我，我将不胜感激。

Answer 1

进一步调查，我发现了我的错误：

使用glVertexAttribPointer时，可以将步幅参数设置为0（零），OpenGL会自动确定步幅；但是，使用 glVertexAttribFormat 时，您必须自己设置步幅。

一旦我在 glVertexAttribFormat 中手动设置步幅值，一切都按预期进行。

如何将 OpenGL 项目从旧的 glVertexAttribPointer 方法转换为新的 glVertexAttribBinding 方法？

Ho do you convert an OpenGL project from older glVertexAttribPointer methods to newer glVertexAttribBinding methods?

opengl

vertex-buffer

vao