paintGL不会在屏幕上绘制任何东西

Question

我想从OpenGL Wiki中基于这个example创建PyQt5/PyOpenGL代码。

paintGL()调用不会在屏幕上显示任何内容。我阅读的类似标题的StackOverflow问题描述了我面临的不同问题：

注意：由于rep限制，此时我无法发布超过2个链接。我添加了所有相关的StackOverflow链接，作为对此问题的注释。

我也经历了Common OpenGL Mistakes页面，它似乎没有帮助（很可能我没有很好地理解页面）。

1. 在创建VAO结合
2. 在创建VBO绑定，
3. 调用glBindVertexArray和glEnableVertexAttribArray

的经过：

的glGetErrors功能在以下所有阶段报告GL.GL_NO_ERRORglGetShaderiv和glGetProgramiv返回GL.GL_TRUE，所以有似乎没有编译和链接错误。

GL上下文似乎已被正确创建。 self.context().isValid()支票返回True。

我使用PyQt5.5，Python 3.4.0与PyOpenGL 3.1。此外，GPU Caps Viewer报告说Open GL 4.5在我的机器上可用。

任何帮助或指示移动是非常赞赏。

代码如下。

from PyQt5 import QtGui, QtCore 
import sys, array 
from OpenGL import GL 


# Create the Vertex Shader script and the Fragment Shader script here. 
DeltaVertexShader = ''' 
#version 420 core 

layout (location = 0) in vec4 vertexPositions; 
layout (location = 1) in vec4 vertexColours; 

smooth out vec4 fragmentColours; 

void main() 
{ 
    gl_Position = vertexPositions; 
    fragmentColours = vertexColours; 
} 
''' 

DeltaFragmentShader = ''' 
#version 420 core 

smooth in vec4 fragmentColours; 
out vec4 finalColours; 

void main() 
{ 
    finalColours = fragmentColours; 
} 
''' 

class PulleysWithWeights3D(QtGui.QOpenGLWindow): 


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

     # These are the 4D coordinates of a triangle that needs to be drawn. 
     _vertexPos = [ 0.075, 0.075, 0.075, 1.0, \ 
         0.275, 0.275, 0.275, 1.0, \ 
         0.550, 0.550, 0.550, 1.0 ] 

     # These are the RGBA colours for each vertex. 
     _vertexCols = [ 0.875, 0.525, 0.075, 0.500, \ 
         0.875, 0.525, 0.075, 0.500, \ 
         0.875, 0.525, 0.075, 0.500 ] 

     self._deltaPositions = array.array('f', _vertexPos) 
     self._deltaColours = array.array('f', _vertexCols) 

     self._appSurfaceFormat = QtGui.QSurfaceFormat() 

     self._appSurfaceFormat.setProfile(QtGui.QSurfaceFormat.CoreProfile) 
     self._appSurfaceFormat.setMajorVersion(4) 
     self._appSurfaceFormat.setMinorVersion(2) 
     self._appSurfaceFormat.setRenderableType(QtGui.QSurfaceFormat.OpenGL) 
     self._appSurfaceFormat.setSamples(16) 
     self._appSurfaceFormat.setSwapBehavior(QtGui.QSurfaceFormat.DoubleBuffer) 
     self.setSurfaceType(QtGui.QSurface.OpenGLSurface) 

     self.setFormat(self._appSurfaceFormat) 

     self.setIcon(QtGui.QIcon('OpenGL.png')) 
     self.setTitle('Pulleys3D') 
     self.setMinimumSize(QtCore.QSize(1280, 640)) 
     self.show() 


    def initializeGL(self): 
     GL.glClearColor(0.0, 0.0, 0.00, 1.0) # RGBA 
     GL.glClearDepthf(1.0) 
     GL.glClearStencil(0) 
     GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT | GL.GL_STENCIL_BUFFER_BIT) 

     # Initialize a VAO. 
     self._vaoColouredDelta = GL.glGenVertexArrays(1) 
     GL.glBindVertexArray(self._vaoColouredDelta) 

     # Initialize the VBOs. 
     self._vboPositions = GL.glGenBuffers(1) # Create the position buffer. 
     self._vboShades = GL.glGenBuffers(1) # Create the colours buffer.   

     # Bind the positions VBO to the GL_ARRAY_BUFFER target. 
     GL.glBindBuffer(GL.GL_ARRAY_BUFFER, self._vboPositions) 

     # Initialize the positions buffer with the positions array data. 
     GL.glBufferData(GL.GL_ARRAY_BUFFER, self._deltaPositions.buffer_info()[1] * self._deltaPositions.itemsize, \ 
         self._deltaPositions.tobytes(), GL.GL_STATIC_DRAW) 

     GL.glEnableVertexAttribArray(0) # Enable attribute array 0, i.e., the positions array. 

     GL.glVertexAttribPointer(0, 4, GL.GL_FLOAT, GL.GL_FALSE, 0, None) 

     GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0) 

     GL.glBindBuffer(GL.GL_ARRAY_BUFFER, self._vboShades) 
     GL.glBufferData(GL.GL_ARRAY_BUFFER, self._deltaColours.buffer_info()[1] * self._deltaColours.itemsize, \ 
         self._deltaColours.tobytes(), GL.GL_STATIC_DRAW) 
     GL.glEnableVertexAttribArray(1) # Enable attribute array 1, i.e., the colours array. 
     GL.glVertexAttribPointer(1, 4, GL.GL_FLOAT, GL.GL_FALSE, 0, None) 

     GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0) 
     GL.glBindVertexArray(0) # Unbind the VAO. 

     # Initialize the vertex shader and fragment shader program objects. 
     _vertexShaderObj = GL.glCreateShader(GL.GL_VERTEX_SHADER) 
     _fragmentShaderObj = GL.glCreateShader(GL.GL_FRAGMENT_SHADER) 

     GL.glShaderSource(_vertexShaderObj, DeltaVertexShader) 
     GL.glShaderSource(_fragmentShaderObj, DeltaFragmentShader) 

     GL.glCompileShader(_vertexShaderObj) 
     GL.glCompileShader(_fragmentShaderObj) 


     if GL.glGetShaderiv(_vertexShaderObj, GL.GL_COMPILE_STATUS) != GL.GL_TRUE: 
      # There was a compilation error. Print it. 
      print('Vertex Shader Compilation failed! Details follow.') 
      print('Compilation errors are: %s ' %(str(GL.glGetShaderInfoLog(_vertexShaderObj)))) 

      # Delete this shader. 
      GL.glDeleteShader(_vertexShaderObj) 
      return # Don't continue execution. 
     elif GL.glGetShaderiv(_fragmentShaderObj, GL.GL_COMPILE_STATUS) != GL.GL_TRUE: 
      print('Fragment Shader Compilation failed! Details follow.') 
      print('Compilation errors are: %s ' %(str(GL.glGetShaderInfoLog(_fragmentShaderObj)))) 

      # Delete this shader. 
      GL.glDeleteShader(_fragmentShaderObj) 
      return # Don't continue execution. 

     self._renderProgram = GL.glCreateProgram() 
     GL.glAttachShader(self._renderProgram, _vertexShaderObj) 
     GL.glAttachShader(self._renderProgram, _fragmentShaderObj) 

     GL.glLinkProgram(self._renderProgram) 


     if GL.glGetProgramiv(self._renderProgram, GL.GL_LINK_STATUS) != GL.GL_TRUE: 
      print('Shader linking failed! Details follow.') 
      print('Linking errors are: %s ' %(str(GL.glGetProgramInfoLog(self._renderProgram)))) 

      GL.glDetachShader(self._renderProgram, _vertexShaderObj) 
      GL.glDetachShader(self._renderProgram, _fragmentShaderObj) 
      GL.glDeleteShader(_vertexShaderObj) 
      GL.glDeleteShader(_fragmentShaderObj) 

      # Delete the program. 
      GL.glDeleteProgram(self._renderProgram) 
      return # Don't continue execution. 

     # Always detach shaders after a successful link. 
     GL.glDetachShader(self._renderProgram, _vertexShaderObj) 
     GL.glDetachShader(self._renderProgram, _fragmentShaderObj) 


    def resizeGL(self, wd, ht): 
     # Resize the viewport by calling glViewport with the new height and width. 
     GL.glViewport(0, 0, wd, ht) 


    def paintGL(self): 
     GL.glClearColor(0.0, 0.0, 0.00, 1.0) # RGBA 
     GL.glClearDepthf(1.0) 
     GL.glClearStencil(0) 
     GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT | GL.GL_STENCIL_BUFFER_BIT) 

     # Initialize the shader program to paint. 
     GL.glUseProgram(self._renderProgram) 

     GL.glBindVertexArray(self._vaoColouredDelta) 

     # Draw the array. 
     GL.glDrawArrays(GL.GL_TRIANGLES, 0, 3) 


     # Swap the front and back buffers so the newly drawn content is visible. 
     self.context().swapBuffers(self) 

     # Unbind the vertex array and the program. 
     GL.glBindVertexArray(0) 
     GL.glUseProgram(0) 


if __name__ == '__main__': 
    _pww3dApp = QtGui.QGuiApplication(sys.argv) 
    _pww3d = PulleysWithWeights3D() 
    sys.exit(_pww3dApp.exec_()) 

Answer 1

使用的XYZ值导致三角形太小而不能被注意呈现。

按比例放大X，Y，Z值将导致显示三角形。例如，

_vertexPos = [ 0.775, 0.775, 0.775, 1.0, \ 
       0.275, 0.275, 0.275, 1.0, \ 
       0.550, 0.550, 0.550, 1.0 ]