Order Independent Transparency

oit.py

import sys
from PyQt5.QtCore import QTimer
from PyQt5.QtWidgets import (QApplication, QMainWindow, QOpenGLWidget,
                             QAction, QActionGroup, QFileDialog)
from OpenGL import GLU, GL
import numpy as np


class GLWidget(QOpenGLWidget):
    def __init__(self, parent=None):
        self.parent = parent
        super().__init__(parent)
        
        self.yRotDeg = 0.0       
        self.render_flag = 0
        self.initGeometry()

    def initializeGL(self):
        GL.glClearColor(1., 1., 1., 1.)
        GL.glEnable(GL.GL_DEPTH_TEST)
        GL.glDisable(GL.GL_CULL_FACE)
        GL.glColorMaterial(GL.GL_FRONT, GL.GL_AMBIENT_AND_DIFFUSE)
        GL.glEnable(GL.GL_COLOR_MATERIAL)
        GL.glShadeModel(GL.GL_SMOOTH)

        ambient = [0.0, 0.0, 0.0, 1.0]
        diffuse = [1.0, 1.0, 1.0, 1.0]
        specular = [1.0, 1.0, 1.0, 1.0]

        light_dir = [1.0, 0.0, 0.0, 0.0]

        GL.glLightfv(GL.GL_LIGHT0, GL.GL_AMBIENT, ambient)
        GL.glLightfv(GL.GL_LIGHT0, GL.GL_DIFFUSE, diffuse)
        GL.glLightfv(GL.GL_LIGHT0, GL.GL_SPECULAR, specular)
        GL.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, light_dir)

        GL.glEnable(GL.GL_LIGHT0)
        GL.glEnable(GL.GL_LIGHTING)

    def resizeGL(self, width, height):
        if height == 0:
            height = 1

        GL.glViewport(0, 0, width, height)
        GL.glMatrixMode(GL.GL_PROJECTION)
        GL.glLoadIdentity()
        aspect = width / float(height)

        GLU.gluPerspective(45.0, aspect, 1.0, 500.0)
        GL.glMatrixMode(GL.GL_MODELVIEW)

    def paintGL(self):
        GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT)
        GL.glLoadIdentity()
        GLU.gluLookAt(0.0, 130.0, 100.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0)       
        GL.glRotate(self.yRotDeg, 0.0, 0.0, 1.0)

        GL.glColor4f(0.42, 0.42, 0.83, 1.0)
        #GL.glColor4f(0.0, 0.0, 1.0, 1.0)
        
        if self.render_flag == 0:
            GL.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_FILL)
        elif self.render_flag == 1:
            GL.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_LINE)
        else:
            GL.glDepthMask(GL.GL_FALSE)
            GL.glEnable(GL.GL_BLEND)
            GL.glBlendFunc(GL.GL_ZERO, GL.GL_ONE_MINUS_SRC_COLOR)

        GL.glEnableClientState(GL.GL_VERTEX_ARRAY)
        GL.glVertexPointerf(self.vertices)
        GL.glEnableClientState(GL.GL_NORMAL_ARRAY)
        GL.glNormalPointerf(self.normals)
        GL.glDrawElementsui(GL.GL_TRIANGLES, self.indices)

        GL.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_FILL)
        GL.glDepthMask(GL.GL_TRUE)
        GL.glDisable(GL.GL_BLEND)

    def initGeometry(self):
        self.vertices = np.loadtxt('vertices.txt', dtype=np.float32)
        self.indices = np.loadtxt('indices.txt', dtype=int)
        self.normals = np.loadtxt('normals.txt', dtype=np.float32)

    def spin(self):
        self.yRotDeg = (self.yRotDeg + 1) % 360.0
        self.parent.statusBar().showMessage('rotation {}'.format(self.yRotDeg))
        self.update()

class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()

        self.resize(500, 500)
        self.setWindowTitle('Order Independent Transparency')

        self.initActions()
        self.initMenus()

        self.glWidget = GLWidget(self)
        self.setCentralWidget(self.glWidget)

        timer = QTimer(self)
        timer.setInterval(20)
        timer.timeout.connect(self.glWidget.spin)
        timer.start()

    def initActions(self):
        self.exitAction = QAction('Quit', self)
        self.exitAction.setShortcut('Ctrl+Q')
        self.exitAction.setStatusTip('Exit application')
        self.exitAction.triggered.connect(self.close)

        self.solidAction = QAction('Show Solid', self)
        self.solidAction.setStatusTip('Show Solid')
        self.solidAction.setCheckable(True)
        self.solidAction.setChecked(True)
        self.solidAction.triggered.connect(self.solid)

        self.wireAction = QAction('Show Wireframe', self)
        self.wireAction.setStatusTip('Show Wireframe')
        self.wireAction.setCheckable(True)
        self.wireAction.triggered.connect(self.wire)

        self.transparentAction = QAction('Show Transparent', self)
        self.transparentAction.setStatusTip('Show Transparent')
        self.transparentAction.setCheckable(True)
        self.transparentAction.triggered.connect(self.transparent)

        action_group = QActionGroup(self)
        action_group.addAction(self.solidAction)
        action_group.addAction(self.wireAction)
        action_group.addAction(self.transparentAction)


    def initMenus(self):
        menuBar = self.menuBar()
        fileMenu = menuBar.addMenu('&File')
        fileMenu.addAction(self.exitAction)

        viewMenu = menuBar.addMenu('View')
        viewMenu.addAction(self.solidAction)
        viewMenu.addAction(self.wireAction)
        viewMenu.addAction(self.transparentAction)

    def wire(self):
        self.glWidget.render_flag = 1
    
    def solid(self):
        self.glWidget.render_flag = 0
    
    def transparent(self):
        self.glWidget.render_flag = 2

app = QApplication(sys.argv)

win = MainWindow()
win.show()

sys.exit(app.exec())