# OpenGLDemo

- `Download example`

OpenGLDemo

OpenGLDemo is probably the simplest possible demonstration of using OpenGL from a PyObjC application. It is a port of Apple’s “CocoaGL” example. Note that this requires PyOpenGL to be installed.

See: /Developer/Examples/OpenGL/Cocoa/CocoaGL

  https://pyopengl.sourceforge.net/

The source of this application demonstrates - Using PyOpenGL from Cocoa

Bob Ippolito bob@redivi.com

## Sources

### OpenGLDemo.py

    """OpenGLDemo.py -- A simple demo of using OpenGL with Cocoa

    To build the demo program, run this line in Terminal.app:

        $ python setup.py py2app -A

    This creates a directory "dist" containing OpenGLDemo.app. (The
    -A option causes the files to be symlinked to the .app bundle instead
    of copied. This means you don't have to rebuild the app if you edit the
    sources or nibs.)

    This example requires PyOpenGL
    """

    from Cocoa import (
        NSOpenGLView,
        NSOpenGLPFANoRecovery,
        NSOpenGLPFAWindow,
        NSOpenGLPFAAccelerated,
        NSOpenGLPFADoubleBuffer,
        NSOpenGLPFAColorSize,
        NSOpenGLPFAAlphaSize,
        NSOpenGLPFADepthSize,
        NSOpenGLPFAStencilSize,
        NSOpenGLPFAAccumSize,
        NSOpenGLPixelFormat,
    )
    from OpenGL.GL import (
        glViewport,
        glClearColor,
        glClear,
        GL_COLOR_BUFFER_BIT,
        GL_DEPTH_BUFFER_BIT,
        GL_STENCIL_BUFFER_BIT,
    )
    from PyObjCTools import AppHelper
    import objc
    from objc import super  # noqa: A004

    ClearColors = redIndex, greenIndex, blueIndex, alphaIndex = range(4)

    class OpenGLDemoView(NSOpenGLView):
        def awakeFromNib(self):
            self.color_index = alphaIndex

        def initWithFrame_(self, frame):
            attribs = [
                NSOpenGLPFANoRecovery,
                NSOpenGLPFAWindow,
                NSOpenGLPFAAccelerated,
                NSOpenGLPFADoubleBuffer,
                NSOpenGLPFAColorSize,
                24,
                NSOpenGLPFAAlphaSize,
                8,
                NSOpenGLPFADepthSize,
                24,
                NSOpenGLPFAStencilSize,
                8,
                NSOpenGLPFAAccumSize,
                0,
            ]
            fmt = NSOpenGLPixelFormat.alloc().initWithAttributes_(attribs)
            self = super().initWithFrame_pixelFormat_(frame, fmt)
            return self

        @objc.IBAction
        def setClearColor_(self, sender):
            self.color_index = sender.tag()
            self.setNeedsDisplay_(True)

        def drawRect_(self, pos, size):
            x, y = pos
            w, h = size
            glViewport(0, 0, w, h)
            clear_color = [0.0] * 4
            clear_color[self.color_index] = 1.0
            glClearColor(*clear_color)
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT)
            self.openGLContext().flushBuffer()

    if __name__ == "__main__":
        AppHelper.runEventLoop()

### setup.py

    """
    Script for building the example.

    Usage:
        python3 setup.py py2app
    """

    from setuptools import setup

    plist = {"NSMainNibFile": "OpenGLDemo"}
    setup(
        name="OpenGLDemo",
        app=["OpenGLDemo.py"],
        data_files=["OpenGLDemo.nib"],
        options={"py2app": {"plist": plist}},
        setup_requires=["py2app", "PyOpenGL", "pyobjc-framework-Cocoa"],
    )