some questions about OpenGL in pyglet.

[xinmi...@163.com]

 I can use from pyglet.gl import * to use OpenGL, in docs, it is said that pyglet provides an interface to OpenGL and GLU. To use it you will need a good knowledge of OpenGL, C and ctypes. To be honest, I know nothing about OpenGL, but I knew OpenGL has its own versions, and which version is used in pyglet? It seemed that there are modern OpenGL (OpenGL 3 and 4) , and  “old” OpenGL (OpenGL 1 and 2). Is there much difference between them? Could I use pyglet to learn OpenGL, or only C++ is fine?

[Benjamin Moran]

Pyglet's OpenGL bindings should support very recent versions. (If not, please file a bug so that they can be updated).

Internally, Pyglet only uses "classic" OpenGL. This older OpenGL is much simpler, and is enough for most simple games and applications. This is what the pyglet text, sprite, and graphics modules are based on.
Modern OpenGL can be used by simply requesting a newer OpenGL context when creating the window. However, you have to give up on the sprite and graphics modules because they will try to call some older OpenGL functions that may not be available with a newer context.

Working with shaders does require knowing some ctypes, but there is a nice library here that hides that: https://github.com/gabdube/pyshaders
I also wrote a very basic shader program wrapper here: https://bitbucket.org/treehousegames/pyglet/src/28d33a50ba8c1f140613ca90de7791260a3d9daa/pyglet/graphics/shader.py?at=shader_class&fileviewer=file-view-default
I would probably not recommend the one i wrote, but it might give you an idea of the ctypes involved. Ctypes is actually very easy to use, but if you don't understand the basic C concepts it will be challenging.

[Simon]

Hi, Ben, 

Many thanks for your detailed explaination, I think I get the ideas. Well, I think I have already meet ctype problems, I want to use glGet() to get values, and the code I wrote.

    for i in range(10):        

        glPointSize(i+0.5)

        a = GLfloat() * 2

        glGetFloatv(GL_POINT_SIZE_RANGE,a)

        print(a)

        glBegin(GL_POINTS)

        glColor3f(1.0,1.0,0.0)

        glVertex3f(i-5.0,1.0,0.0)

        glEnd()

It does not work, I think I meet the problem of ctypes, I read your code you showed to me, it is precise. I will check the Ctypes first, thank you very much!

BTW, it seemed that my post is auto to be a maillist. ^ v ^ Maybe I can reply it by E-mail instead of VPN. 

在 2016年12月4日星期日 UTC+8下午10:17:14，Benjamin Moran写道：

[Benjamin Moran]

Hi Simon,

You almost got it. You have to create ctypes arrays like this:   "a = (GLfloat * 2)()".  I know it looks a little funny, but oh well.
Also, if you want to print it, you have to type "print(a[:])". Here is a working example:

for i in range(10):        

   glPointSize(i+0.5)

   a = (GLfloat * 2)()

   glGetFloatv(GL_POINT_SIZE_RANGE, a)

   print(a[:])

   glBegin(GL_POINTS)

   glColor3f(1.0,1.0,0.0)

       glVertex3f(i-5.0,1.0,0.0)

       glEnd()

[xinming]

Many thanks! It would save me a lot of time to find the trick ^ v ^

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