用PYQT5和OpenGL绘制一个三角形（重写Qt C++实例）

Question

我当前的PyQt5示例没有显示窗口，也没有给我任何错误消息

这是QT+C++的例子，非常好。我想在我的PyQt5代码中使用QOpenGLBuffer

main.cpp

#include <QApplication>
#include <QOpenGLWidget>
#include <QOpenGLShaderProgram>
#include <QOpenGLBuffer>

class Widget : public QOpenGLWidget {
    Q_OBJECT
public:
    Widget(QWidget *parent = nullptr) : QOpenGLWidget(parent) { }
private:
    QOpenGLShaderProgram m_program;
    QOpenGLBuffer m_vertPosBuffer;

    void initializeGL() override {
        glClearColor(0.5f, 0.8f, 0.7f, 1.f);
        resize(400, 500);
        const char *vertShaderSrc =
                "attribute vec3 aPosition;"
                "void main()"
                "{"
                "    gl_Position = vec4(aPosition, 1.0);"
                "}";
        const char *fragShaderSrc =
                "void main()"
                "{"
                "    gl_FragColor = vec4(0.5, 0.2, 0.9, 1.0);"
                "}";
        m_program.addShaderFromSourceCode(QOpenGLShader::Vertex, vertShaderSrc);
        m_program.addShaderFromSourceCode(QOpenGLShader::Fragment, fragShaderSrc);
        m_program.link();
        m_program.bind();
        float vertPositions[] = {
            -0.5f, -0.5f, 0.f,
            0.5f, -0.5f, 0.f,
            0.f, 0.5f, 0.f
        };
        m_vertPosBuffer.create();
        m_vertPosBuffer.bind();
        m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));
        m_program.bindAttributeLocation("aPosition", 0);
        m_program.setAttributeBuffer(0, GL_FLOAT, 0, 3);
        m_program.enableAttributeArray(0);
    }
    void paintGL() override {
        glClear(GL_COLOR_BUFFER_BIT);
        glDrawArrays(GL_TRIANGLES, 0, 3);
    }
    void resizeGL(int w, int h) override {
        glViewport(0, 0, w, h);
    }
};

#include "main.moc"

int main(int argc, char *argv[]) {
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}

这是我试图将上面的代码重写为PyQt5的过程。正如你看到的，我想重写它非常接近Qt C++。我想举两个非常相似的例子。但此代码不显示windows窗口，也不显示任何错误消息

main.py

import sys
import numpy as np
from OpenGL import GL as gl
from PyQt5.QtWidgets import QOpenGLWidget, QApplication
from PyQt5.QtGui import (QOpenGLBuffer, QOpenGLShaderProgram,
    QOpenGLShader)
from PyQt5.QtCore import Qt

class OpenGLWidget(QOpenGLWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Triangle, PyQt5, OpenGL ES 2.0")
        self.resize(300, 300)
    def initializeGL(self):
        gl.glClearColor(0.5, 0.8, 0.7, 1.0)
        vertShaderSrc = """
            attribute vec3 aPosition;
            void main()
            {
                gl_Position = vec4(aPosition, 1.0);
            }
        """
        fragShaderSrc = """
            void main()
            {
                gl_FragColor = vec4(0.5, 0.2, 0.9, 1.0);
            }
        """
        program = QOpenGLShaderProgram()
        program.addShaderFromSourceCode(QOpenGLShader.Vertex, vertShaderSrc)
        program.addShaderFromSourceCode(QOpenGLShader.Fragment, fragShaderSrc)
        program.link()
        program.bind()
        vertPositions = np.array([
            -0.5, -0.5, 0.0,
            0.5, -0.5, 0.0,
            0.0, 0.5, 0.0], dtype=np.float32)
        vertPosBuffer = QOpenGLBuffer()
        vertPosBuffer.create()
        vertPosBuffer.bind()
        vertPosBuffer.allocate(vertPositions, len(vertPositions) * 4)
        program.bindAttributeLocation("aPosition", 0)
        program.setAttributeBuffer(0, gl.GL_FLOAT, 0, 3)
        program.enableAttributeArray(0)

    def paintGL(self):
        gl.glClear(gl.GL_COLOR_BUFFER_BIT)
        gl.glDrawArrays(gl.GL_TRIANGLES, 0, 3)

def main():
    QApplication.setAttribute(Qt.AA_UseDesktopOpenGL)
    a = QApplication(sys.argv)
    w = OpenGLWidget()
    w.show()
    sys.exit(a.exec_())

if __name__ == "__main__":
    main()

Answer 1

问题是Qopunl缓冲区是一个局部变量，它是瞬间被破坏的，而C++中的QOpenGLBuffer是类的属性。解决方法是将vertPosBuffer更改为self.vertPosBuffer