使用PyQt5和OpenGL绘制三角形(重写Qt C++示例)

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QtC++的一个非常好的例子。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。正如你所看到的，我想把它重写得非常接近QtC++。我想要两个非常相似的例子。但此代码不显示窗口，也不显示任何错误消息。

主.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QOpenGLBuffer是一个立即销毁的局部变量，而在C++中，QOpenGLBuffer是类的一个属性。解决方案是将vertPosBuffer更改为self.vertPosBuffer