[PyOpenGL-Users] Question on glBufferData / glBufferSubData

[Walter W. <hom...@gm...>]

Hello,

I have a question about PyOpenGL and hope that you can help me.

I am a little bit confused about the follwing.

This works fine:

glBufferData(GL_ARRAY_BUFFER, ADT.arrayByteCount(npData), 	
              ADT.voidDataPointer(npData), GL_STATIC_DRAW)

This also works fine:

glBufferSubData(GL_ARRAY_BUFFER, 0, ADT.arrayByteCount(npData), npData)

But using this results in OpenGL Error 1281 Invalid Type after a few
seconds:

glBufferSubData(GL_ARRAY_BUFFER, 0, ADT.arrayByteCount(npData), 
ADT.voidDataPointer(npData))

I don't understand why using ADT.voidDataPointer(npData) in the
latter does not work as the specification states the that
the type is a void pointer to the data array in both functions:

void glBufferSubData(GLenum target,  GLintptr offset,  GLsizeiptr size, 
  const GLvoid * data);

void glBufferData(GLenum target,  GLsizeiptr size,  const GLvoid * data, 
  GLenum usage);

Kind regards,
Walter