英文:
glEnableClientState vs shader's attribute location
问题
以下是代码部分的中文翻译：
// 使用以下函数将VBO数据与着色器的属性连接起来：
GLint attribVertexPosition = glGetAttribLocation(progId, "vertexPosition");
glEnableVertexAttribArray(attribVertexPosition);
glVertexAttribPointer(attribVertexPosition, 3, GL_FLOAT, false, 0, 0);
// 我分析了一个使用以下函数的旧版OpenGL代码，其中使用了VBO：
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, 0);
旧版代码如何将VBO数据与着色器的属性"vertexPosition"建立连接：
attribute vec3 vertexPosition;
英文:
I can connect a VBO data with the shader's attribute using the followings functions:
GLint attribVertexPosition = glGetAttribLocation(progId, "vertexPosition");
glEnableVertexAttribArray(attribVertexPosition);
glVertexAttribPointer(attribVertexPosition, 3, GL_FLOAT, false, 0, 0);
I analyze a legacy OpenGL code where a VBO is used with the following functions:
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, 0);
How that legacy code makes a connnection between a VBO data and the shader's attribute:
attribute vec3 vertexPosition;
?
答案1
得分: 3
对于这些固定功能函数，缓冲区与顶点属性之间的绑定是固定的。您不需要告诉 glVertexArray 它馈送哪个属性；它 始终 馈送属性 gl_Vertex，该属性在着色器中已为您定义。它无法馈送任何用户定义的属性。
用户定义的属性是与固定功能属性分开的一组属性。
请注意，NVIDIA 硬件已知违反了这个规则。它将某些属性位置与某些内置顶点数组别名，这允许用户定义的属性从固定功能数组中接收数据。也许您正在查看依赖于这种仅在NVIDIA实现中可用的非标准行为的代码。
英文:
For these fixed-function functions, the binding between the buffer and the vertex attribute is fixed. You don't tell glVertexArray which attribute it feeds; it always feeds the attribute gl_Vertex, which is defined for you in the shader. It cannot feed any user-defined attribute.
User-defined attributes are a separate set of attributes from the fixed-functioned ones.
Note that NVIDIA hardware is known to violate this rule. It aliases certain attribute locations with certain built-in vertex arrays, which allows user-defined attributes to receive data from fixed-function arrays. Perhaps you are looking at code that relies on this non-standard behavior that is only available on NVIDIA's implementation.
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