import numpy as np
from OpenGL import GL, GLU
from PyQt5.QtWidgets import QOpenGLWidget, QApplication

global eyeX, eyeY, eyeZ


# gluLookAt 'eye' coordinates
eyeX = 0.0 
eyeY = 0.0
eyeZ = 10.0

class OpenGLWidget(QOpenGLWidget):

    def initializeGL(self):

        GL.glClearColor(0,0,0,1);
#         GL.glEnable(GL.GL_DEPTH_TEST);
#         GL.glEnable(GL.GL_LIGHT0);
#         GL.glEnable(GL.GL_LIGHTING);
#         GL.glColorMaterial(GL.GL_FRONT_AND_BACK, GL.GL_AMBIENT_AND_DIFFUSE);
#         GL.glEnable(GL.GL_COLOR_MATERIAL);
        
        GL.glMatrixMode(GL.GL_PROJECTION);
        GL.glOrtho(-10.0, 10.0, -10.0, 10.0, -10.0, 10.0)
        GL.glClear(GL.GL_COLOR_BUFFER_BIT)
        GL.glMatrixMode(GL.GL_MODELVIEW);
        GL.glLoadIdentity();
        
        #GL.glClearColor(1.0, 0.0, 1.0, 0.0);
#         vertices = np.array([0.0, 1.0, -1.0, -1.0, 1.0, -1.0], dtype=np.float32)
# 
#         bufferId = GL.glGenBuffers(1)
#         GL.glBindBuffer(GL.GL_ARRAY_BUFFER, bufferId)
#         GL.glBufferData(GL.GL_ARRAY_BUFFER, vertices.nbytes, vertices, GL.GL_STATIC_DRAW)
# 
#         GL.glEnableVertexAttribArray(0)
#         GL.glVertexAttribPointer(0, 2, GL.GL_FLOAT, GL.GL_FALSE, 0, None)

    def paintGL(self):
#         GL.glDrawArrays(GL.GL_TRIANGLES, 0, 3)
        GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
    
        GLU.gluLookAt(eyeX, eyeY, eyeZ,
                      0.0, 0.0, 0.0,
                      0.0, 1.0, 0.0);
#         GL.glBegin(GL.GL_TRIANGLES);
#         GL.glColor3f(1.0, 0.0, 0.0);
#         GL.glVertex3f(-0.5, -0.5, 0);
#         GL.glColor3f(0.0, 1.0, 0.0);
#         GL.glVertex3f( 0.5, -0.5, 0);
#         GL.glColor3f(0.0, 0.0, 1.0);
#         GL.glVertex3f( 0.0,  0.5, 0);
#         GL.glEnd();

        from math import sin, cos
        radius = 0.5
        halfLength = 3.0
        slices = 10
        
        for i in range(slices):
            theta = float(i) * 2.0 * 3.14 / float(slices)
            nextTheta = float(i + 1) * 2.0 * 3.14 / float(slices)
            
            GL.glColor3f(1.0, 0.0, 0.0)
            GL.glBegin(GL.GL_TRIANGLE_STRIP)
            
            GL.glVertex3f(0.0, halfLength, 0.0)
            GL.glVertex3f(radius*cos(theta), halfLength, radius*sin(theta))
            GL.glVertex3f (radius*cos(nextTheta), halfLength, radius*sin(nextTheta))
            
            GL.glVertex3f (radius*cos(nextTheta), -halfLength, radius*sin(nextTheta))
            GL.glVertex3f(radius*cos(theta), -halfLength, radius*sin(theta))
            GL.glVertex3f(0.0, -halfLength, 0.0)
            
            GL.glEnd()


app = QApplication([])
widget = OpenGLWidget()
widget.show()

app.exec_()