當我編譯着色器時，PyOpengGL 引發錯誤

Question

我正在瀏覽大量 OpenGL 着色器教程以及混合和匹配內容，試圖實現自定義着色器。 我有以下 Python 代碼和回溯：

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QOpenGLWidget
from PyQt5.QtCore import Qt
from OpenGL.GL import (
                       glLoadIdentity, glTranslatef, glRotatef,
                       glClear, glBegin, glEnd,
                       glColor3fv, glVertex3fv,
                       GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT,
                       GL_QUADS, GL_LINES,
                       shaders, GL_VERTEX_SHADER, GL_FRAGMENT_SHADER
                      )
from OpenGL.GLU import gluPerspective

class mainWindow(QMainWindow):    #Main class.
    def keyPressEvent(self, event):    #This is the keypress detector.
        try:
            key = event.key()
        except:
            key = -1    
        #print(key)
        if key == 16777216:
            exit()

    vertices = [
                (-1, 1, 0),
                (1, 1, 0),
                (1, -1, 0),
                (-1, -1, 0)
               ]
    wires = [
             (0, 1),
             (1, 2),
             (2, 3),
             (0, 3)
            ]
    facets = [
             (0, 1, 2, 3)
            ]
    zoomLevel = -5
    rotateDegreeH = 0
    rotateDegreeV = -45

    vertShaderCode = """#version 120    
void main() {
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}"""
    fragShaderCode = """#version 120
void main() {
    gl_FragColor = vec4( 0, 1, 0, 1 );
}"""

    def __init__(self):
        super(mainWindow, self).__init__()
        self.sizeX = 700    #Variables used for the setting of the size of everything
        self.sizeY = 600
        self.setGeometry(0, 0, self.sizeX + 50, self.sizeY)    #Set the window size

        #make shaders
        VERTEX_SHADER = shaders.compileShader(self.vertShaderCode, GL_VERTEX_SHADER)

        FRAGMENT_SHADER = shaders.compileShader(self.fragShaderCode, GL_FRAGMENT_SHADER)

        self.shader = shaders.compileProgram(VERTEX_SHADER,FRAGMENT_SHADER)

        self.openGLWidget = QOpenGLWidget(self)    #Create the GLWidget
        self.openGLWidget.setGeometry(0, 0, self.sizeX, self.sizeY)
        self.openGLWidget.initializeGL()
        self.openGLWidget.resizeGL(self.sizeX, self.sizeY)    #Resize GL's knowledge of the window to match the physical size?
        self.openGLWidget.paintGL = self.paintGL    #override the default function with my own?

    def nav(self, hVal = 0, vVal = 0, zVal = 0):
        self.zoomLevel += zVal
        self.rotateDegreeH += hVal
        self.rotateDegreeV += vVal
        self.openGLWidget.update()

    def paintGL(self):
        #This function uses shape objects, such as cube() or mesh(). Shape objects require the following:
        #a list named 'vertices' - This list is a list of points, from which edges and faces are drawn.
        #a list named 'wires'    - This list is a list of tuples which refer to vertices, dictating where to draw wires.
        #a list named 'facets'   - This list is a list of tuples which refer to vertices, ditating where to draw facets.
        #a bool named 'render'   - This bool is used to dictate whether or not to draw the shape.
        #a bool named 'drawWires' - This bool is used to dictate whether wires should be drawn.
        #a bool named 'drawFaces' - This bool is used to dictate whether facets should be drawn.

        shaders.glUseProgram(self.shader)
        glLoadIdentity()
        gluPerspective(45, self.sizeX / self.sizeY, 0.1, 110.0)    #set perspective?
        glTranslatef(0, 0, self.zoomLevel)    #I used -10 instead of -2 in the PyGame version.
        glRotatef(self.rotateDegreeV, 1, 0, 0)    #I used 2 instead of 1 in the PyGame version.
        glRotatef(self.rotateDegreeH, 0, 0, 1)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

        glBegin(GL_LINES)

        for w in self.wires:
            for v in w:
                glVertex3fv(self.vertices[v])
        glEnd()

        glBegin(GL_QUADS)

        for f in self.facets:
            for v in f:
                glVertex3fv(self.vertices[v])
        glEnd()

app = QApplication([])
window = mainWindow()
window.show()
sys.exit(app.exec_())

C:\Users\ccronk22\Documents\Python\glShaders>pygl002.py
Traceback (most recent call last):
  File "C:\Users\ccronk22\AppData\Local\Programs\Python\Python38\lib\site-packages\OpenGL\latebind.py", line 43, in __call__
    return self._finalCall( *args, **named )
TypeError: 'NoneType' object is not callable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\ccronk22\Documents\Python\glShaders\pyGL002.py", line 109, in <module>
    window = mainWindow()
  File "C:\Users\ccronk22\Documents\Python\glShaders\pyGL002.py", line 59, in __init__
    VERTEX_SHADER = shaders.compileShader(self.vertShaderCode, GL_VERTEX_SHADER)
  File "C:\Users\ccronk22\AppData\Local\Programs\Python\Python38\lib\site-packages\OpenGL\GL\shaders.py", line 228, in compileShader
    shader = glCreateShader(shaderType)
  File "C:\Users\ccronk22\AppData\Local\Programs\Python\Python38\lib\site-packages\OpenGL\latebind.py", line 46, in __call__
    self._finalCall = self.finalise()
  File "C:\Users\ccronk22\AppData\Local\Programs\Python\Python38\lib\site-packages\OpenGL\extensions.py", line 242, in finalise
    raise error.NullFunctionError(
OpenGL.error.NullFunctionError: Attempt to call an undefined alternate function (glCreateShader, glCreateShaderObjectARB), check for bool(glCreateShader) before calling

C:\Users\ccronk22\Documents\Python\glShaders>

如果您將 compileShader、compileProgram 和 useProgram 行注釋掉，則上述代碼運行良好。 從上面的角度看，它會產生一個白色方塊：

    def __init__(self):
        super(mainWindow, self).__init__()
        self.sizeX = 700    #Variables used for the setting of the size of everything
        self.sizeY = 600
        self.setGeometry(0, 0, self.sizeX + 50, self.sizeY)    #Set the window size

        #make shaders
        #VERTEX_SHADER = shaders.compileShader(self.vertShaderCode, GL_VERTEX_SHADER)

        #FRAGMENT_SHADER = shaders.compileShader(self.fragShaderCode, GL_FRAGMENT_SHADER)

        #self.shader = shaders.compileProgram(VERTEX_SHADER,FRAGMENT_SHADER)
[…]
    def paintGL(self):
        #This function uses shape objects, such as cube() or mesh(). Shape objects require the following:
        #a list named 'vertices' - This list is a list of points, from which edges and faces are drawn.
        #a list named 'wires'    - This list is a list of tuples which refer to vertices, dictating where to draw wires.
        #a list named 'facets'   - This list is a list of tuples which refer to vertices, ditating where to draw facets.
        #a bool named 'render'   - This bool is used to dictate whether or not to draw the shape.
        #a bool named 'drawWires' - This bool is used to dictate whether wires should be drawn.
        #a bool named 'drawFaces' - This bool is used to dictate whether facets should be drawn.

        #shaders.glUseProgram(self.shader)

一些附加信息：

我試圖讓http://pyopengl.sourceforge.net/context/tutorials/shader_1.html 中的代碼在 PyQt5 上下文中工作，只有 OpenGL 和 PyQt5 API。 本教程是用 Python2 編寫的。 我正在使用 Python3。

那么，我的着色器編譯有什么問題？ 它是在 Python 還是 GLSL 中？

Answer 1

要編譯和鏈接着色器，您需要一個有效的當前OpenGL 上下文。 請注意，當調用任何 OpenGL 指令時，OpenGL 上下文必須是最新的。 QOpenGLWidget提供虛擬方法

def initializeGL () def paintGL () def resizeGL (w, h)

OpenGL 上下文處於活動狀態的位置。 此方法是回調並由 Qts 事件處理調用。 不要在你的代碼中調用它們。

在initializeGL回調中創建着色器：

class mainWindow(QMainWindow):

    def __init__(self):
        super(mainWindow, self).__init__()
        self.sizeX = 700    #Variables used for the setting of the size of everything
        self.sizeY = 600
        self.setGeometry(0, 0, self.sizeX + 50, self.sizeY)    #Set the window size

        self.openGLWidget = QOpenGLWidget(self)    #Create the GLWidget
        self.openGLWidget.setGeometry(0, 0, self.sizeX, self.sizeY)
        self.openGLWidget.resizeGL(self.sizeX, self.sizeY)    #Resize GL's knowledge of the window to match the physical size?
        self.openGLWidget.initializeGL = self.initializeGL 
        self.openGLWidget.paintGL = self.paintGL    #override the default function with my own?
        self.shader = None

    def nav(self, hVal = 0, vVal = 0, zVal = 0):
        self.zoomLevel += zVal
        self.rotateDegreeH += hVal
        self.rotateDegreeV += vVal
        self.openGLWidget.update()

    def initializeGL(self):
        #make shaders
        VERTEX_SHADER = shaders.compileShader(self.vertShaderCode, GL_VERTEX_SHADER)
        FRAGMENT_SHADER = shaders.compileShader(self.fragShaderCode, GL_FRAGMENT_SHADER)
        self.shader = shaders.compileProgram(VERTEX_SHADER,FRAGMENT_SHADER)

    def paintGL(self):

        glUseProgram(self.shader)
        # [...]

（您的代碼中缺少glUseProgram的導入）