1
在使用openGL紋理時，我遇到了python3/qt5/openGL的奇怪行爲。Qt/openGL紋理無法正常工作
在兩個單獨的窗口中打開兩個QOpenGLWidgets，導致兩個Widget之間的OpenGL紋理混合 - 更改第一個Widget中的紋理，導致第二個Widget中的紋理更改。雖然他們應該有不同的openGL上下文。
提供演示此問題的代碼（請參閱下文） - 請在提出解決方案之前先嚐試一下。代碼緊湊演示了兩種情況：
1）創建共享相同的父窗口部件
- 廠確定兩個的QOpenGLWidgets - 沒有「紋理混合」
2）創建兩個QOpenGLWidgets沒有父母
- 小工具作爲開放各個窗口
- 的QT/OpenGL的系統弄亂OpenGL紋理：在第一個窗口中改變紋理，意外改變第二個窗口的紋理！ （記住要調整/點擊第二個窗口中看到這一點）
爲了修復情況（2），我還試圖迫使這兩個部件共享相同的OpenGLContext ..但沒有成功。
http://doc.qt.io/qt-5/qopenglwidget.html
說以下內容：
創建額外QOpenGLContext情況下想與QOpenGLWidget的背景紋理共享資源也是可能的。調用QOpenGLContext ::創建（）
是前「簡單的」通）從上下文（）以QOpenGLContext :: setShareContext（返回的指針，我可以實例化一個自定義QOpenGLContext共享，但沒有辦法強迫使用該自定義上下文的QOpenGLWidget：QOpenGLWidget自動實例化QOpenGLContext某處（其中？）..我只能在initializeGL（使用「self.context（）」）訪問它，但在此時上下文的「.create（）」方法已經被稱爲..！ ..因此沒有辦法填充我的自定義QOpenGLContext任何地方。
我也試過如下：我們創建一個類變量
glcontext=None
在widget的（請參閱第一下面的完整的示例）initializeGL方法我試圖做到這一點：
if (VideoImageWidget.glcontext==None):
print("VideoImageWidget: initializeGL: creating context for sharing")
VideoImageWidget.glcontext=QtGui.QOpenGLContext()
ok=VideoImageWidget.glcontext.create()
print("VideoImageWidget: initializeGL: created context for sharing",VideoImageWidget.glcontext,ok)
context=self.context()
print("VideoImageWidget: initializeGL: automatically created context:",context)
context.setShareContext(VideoImageWidget.glcontext)
ok=context.create() # must call this ..
print("VideoImageWidget: initializeGL: recreated my context:",ok)
但是這不起作用..沒有圖像出現在VideoImageWidget了。
這是一團糟！幫助高度讚賞！
相關：
Is it possible to use the same OpenGL context between top-level windows in Qt?
How to share OpenGL context or data?
演示程序：
import sys
import time
from PyQt5 import QtWidgets, QtCore, QtGui # Qt5
from OpenGL.GL import *
from PIL import Image
"""
Demonstrating a bug (?) in QOpenGLWidget/Qt OpenGL insfrastructure :
You need:
* to have two tiff images ("base.tif" and "2.tif") in the same directory
* to remove/install some libraries:
sudo apt-get install python3-pyqt5 pip3
sudo apt-get remove python3-opengl # we want the most recent version of the opengl bindings
sudo pip3 install PyOpenGL PyOpenGL_accelerate
sudo pip3 install imutils
Usage:
* look for the tag "TOGGLE HERE" below to switch between nested QWidgets/individual windows
* run program with
python3 context_test.py
What's going on here?
* Press the button a few times : a new image appears to the first widget
* The image should appear only to the first widget
* .. but it appears in both widgets if we set "nested=False", i.e. when the widgets constitute individual windows
* .. confirm this by clicking/resizing the second window after clicking the button a few times
Why this happens?
* Qt creates some sort of "top-level" (?) opengl context that is referring to the same texture ids = bug ?
This code is licensed under the do-with-it-whatever-you-want license, written by Sampsa Riikonen, 2017
"""
def getImg(fname):
im =QtGui.QImage(fname)
im =im.convertToFormat(QtGui.QImage.Format_RGB888)
ix =im.width()
iy =im.height()
ptr=im.bits()
ptr.setsize(im.byteCount())
return ptr.asstring(), ix, iy
class VideoImageWidget(QtWidgets.QOpenGLWidget): # http://doc.qt.io/qt-5/qopenglwidget.html # Qt5
def __init__(self,parent=None):
super().__init__(parent=parent)
self.parent=parent
self.baseimage, self.ix, self.iy =getImg("base.tif")
self.gl_format=GL_RGB
self.ratio =1
self.picratio =1
def changeTexture(self,image,ix,iy):
glBindTexture(GL_TEXTURE_2D, self.tex) # this is the texture we will manipulate
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexImage2D(GL_TEXTURE_2D, 0, self.gl_format, ix, iy, 0, self.gl_format, GL_UNSIGNED_BYTE, image) # load bitmap to texture
self.picratio=self.iy/self.ix
def resetTexture(self):
self.changeTexture(self.baseimage,self.ix,self.iy)
def initializeGL(self):
# "This function should set up any required OpenGL resources and state"
glEnable(GL_TEXTURE_2D)
self.tex = glGenTextures(1) # create a new texture
# https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGenTextures.xml
# "it is guaranteed that none of the returned names was in use immediately before the call"
print("VideoImageWidget: glGenTextures returned:",self.tex)
self.resetTexture()
def paintGL(self):
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) # Clear The Screen And The Depth Buffer
glLoadIdentity() # Reset The View
glBindTexture(GL_TEXTURE_2D, self.tex) # this is the texture we will manipulate
glBegin(GL_QUADS)
dz=0
r=self.ratio/self.picratio # screen h/w // picture h/w
if (r<1): # screen wider than image
dy=1
dx=r
elif (r>1): # screen taller than image
dx=1
dy=1/r
else:
dx=1
dy=1
glTexCoord2f(0.0, 0.0); glVertex3f(-dx, dy, dz)
glTexCoord2f(1.0, 0.0); glVertex3f(dx, dy, dz)
glTexCoord2f(1.0, 1.0); glVertex3f(dx,-dy, dz)
glTexCoord2f(0.0, 1.0); glVertex3f(-dx,-dy, dz)
glEnd()
def resizeGL(self, width, height):
"""Called upon window resizing: reinitialize the viewport.
"""
glViewport(0, 0, width, height)
glLoadIdentity()
glOrtho(-1, 1, 1, -1, -1, 1)
self.ratio=height/width
@QtCore.pyqtSlot(object)
def frameReceived(self,frame):
buf =frame[0]
width =frame[1]
height=frame[2]
print("VideoImageWidget updating with frame",width,height)
self.changeTexture(buf,width,height)
self.update()
class MyGui(QtWidgets.QMainWindow):
f1 = QtCore.pyqtSignal(object)
f2 = QtCore.pyqtSignal(object)
def __init__(self,parent=None):
super().__init__(parent)
self.cw=QtWidgets.QWidget(self)
self.setCentralWidget(self.cw)
self.lay = QtWidgets.QVBoxLayout(self.cw)
self.b = QtWidgets.QPushButton("Send frame",self.cw)
# *** TOGGLE HERE ***
# nested=True # *** widgets sitting in the QMainWindow
nested=False # *** individual windows
self.lay.addWidget(self.b)
if (nested):
self.v1 = VideoImageWidget(parent=self.cw)
self.v2 = VideoImageWidget(parent=self.cw)
self.lay.addWidget(self.v1)
self.lay.addWidget(self.v2)
else:
self.v1 = VideoImageWidget(parent=None)
self.v2 = VideoImageWidget(parent=None)
self.v1.show()
self.v2.show()
self.b.clicked. connect(self.clicked)
self.f1. connect(self.v1.frameReceived)
self.newimage, self.ix, self.iy =getImg("2.tif")
@QtCore.pyqtSlot()
def clicked(self):
print("emitting frame")
self.f1.emit([self.newimage, self.ix, self.iy]) # update _only_ the first VideoImageWidget
if (__name__=="__main__"):
app=QtWidgets.QApplication([])
# *** Set this to apply context sharing ***
# app.setAttribute(QtCore.Qt.AA_ShareOpenGLContexts)
"""
.. but that does not work for textures
See the last comment on this post:
https://stackoverflow.com/questions/29838356/is-it-possible-to-use-the-same-opengl-context-between-top-level-windows-in-qt
"I've realised that this does not solve the problem in the question, as it does not actually share the context, but enables sharing of a subset of resources .."
That is said also in the qt docs, but in an extremely implicit way..
http://doc.qt.io/qt-5/qopenglwidget.html
"Creating extra QOpenGLContext instances that share resources like textures .. "
"""
print("OpenGL context sharing status:",app.testAttribute(QtCore.Qt.AA_ShareOpenGLContexts))
mg=MyGui()
mg.show()
app.exec_()
感謝「採樣」！它上帝****工程..！ –