使用glGetFloatv检索pyglet中的modelview矩阵

问题描述

我正在使用pyglet在python中进行3d可视化，并且需要检索modelview和投影矩阵以进行一些选择.我使用以下命令定义窗口:

I'm doing 3d visualization in python using pyglet, and need to retrieve the modelview and projection matrices to do some picking. I define my window using:

from pyglet.gl import *
from pyglet.window import *

win = Window(fullscreen=True, visible=True, vsync=True)

然后定义所有窗口事件:

I then define all of my window events:

@win.event
def on_draw():
    # All of the drawing happens here

@win.event
def on_mouse_release(x, y, button, modifiers):
    if button == mouse.LEFT:

    # This is where I'm having problems
    a = GLfloat()
    mvm = glGetFloatv(GL_MODELVIEW_MATRIX, a)
    print a.value

当我单击时，它将打印...

When I click, it will print...

1.0
Segmentation fault

并崩溃.使用GL_MODELVIEW_MATRIX调用glGetFloatv应该返回16个值，但我不确定如何处理.我尝试定义a = GLfloat * 16，但出现以下错误:

and crash. Calling glGetFloatv with GL_MODELVIEW_MATRIX is supposed to return 16 values, and I'm not exactly sure how to handle that. I tried defining a = GLfloat*16 but I get the following error:

ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: expected LP_c_float instance instead of _ctypes.PyCArrayType

如何检索这些矩阵?

推荐答案

您需要传递16个元素的float数组.为此，请使用以下代码:

You need to pass 16 element float array. To do that use following code:

  a = (GLfloat * 16)()
  mvm = glGetFloatv(GL_MODELVIEW_MATRIX, a)
  print list(a)

当然，您可以使用[0]语法访问"a"的各个元素.

Of course, you can access individual elements of "a" by using a[0] syntax.

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