a triangle, using a pyglet vertex_list

triangle.py

# triangle.py
# by Dave Pape, for DMS 423
#
# Basic pyglet/OpenGL program to draw a single red triangle using a vertex list

from pyglet.gl import *

window = pyglet.window.Window()

# Create the vertex_list - 3 vertices, with 2-dimensional position data, and nothing else
vlist = pyglet.graphics.vertex_list(3, ('v2f', [0,0, 400,50, 200,300]))

@window.event
def on_draw():
    glClear(pyglet.gl.GL_COLOR_BUFFER_BIT)
    glColor3f(1,0,0)
    vlist.draw(GL_TRIANGLES)

pyglet.app.run()

15 glClear(pyglet.gl.GL_COLOR_BUFFER_BIT)
can be replaced with:
15 glClear(GL_COLOR_BUFFER_BIT)
because all pyglet.gl has already been imported