Python Qt : particles with pygame and pyqt6.

Today, I test one python script with pygame and pyqt6. The python script use classes and show particles. See the result:

This is the source code:

import sys
import random
import pygame
from pygame import Vector2
from PyQt6.QtWidgets import (
    QApplication, QWidget, QVBoxLayout, QHBoxLayout,
    QSlider, QLabel, QSizePolicy
)
from PyQt6.QtCore import Qt, QTimer
from PyQt6.QtGui import QImage, QPainter

class Particle:
    def __init__(self, pos, vel, color):
        self.pos = Vector2(pos)
        self.vel = Vector2(vel)
        self.color = color
        self.life = 255

    def update(self, gravity):
        self.vel.y += gravity
        self.pos += self.vel
        self.life -= 2

    def draw(self, surf):
        if self.life > 0:
            pygame.draw.circle(
                surf,
                self.color,
                (int(self.pos.x), int(self.pos.y)),
                4
            )


class PygameWidget(QWidget):
    def __init__(self):
        super().__init__()

        pygame.init()
        pygame.display.init()

        self.w, self.h = 900, 600
        self.surface = pygame.Surface((self.w, self.h))

        self.particles = []
        self.spawn_rate = 5
        self.gravity = 0.1

        self.setSizePolicy(
            QSizePolicy.Policy.Expanding,
            QSizePolicy.Policy.Expanding
        )

        self.timer = QTimer()
        self.timer.timeout.connect(self.game_loop)
        self.timer.start(16)  # ~60 FPS

    def spawn_particles(self):
        for _ in range(self.spawn_rate):
            pos = (self.w // 2, self.h // 2)
            vel = (random.uniform(-2, 2), random.uniform(-2, 2))
            color = (255, random.randint(100, 255), 0)
            self.particles.append(Particle(pos, vel, color))

    def game_loop(self):
        self.surface.fill((20, 20, 20))

        self.spawn_particles()

        alive = []
        for p in self.particles:
            p.update(self.gravity)
            p.draw(self.surface)
            if p.life > 0:
                alive.append(p)

        self.particles = alive

        self.update()

    def paintEvent(self, event):
        data = pygame.image.tobytes(self.surface, "RGB")
        img = QImage(
            data,
            self.w,
            self.h,
            self.w * 3,
            QImage.Format.Format_RGB888
        )

        painter = QPainter(self)
        painter.drawImage(0, 0, img)
        painter.end()

    def resizeEvent(self, event):
        self.w = self.width()
        self.h = self.height()
        self.surface = pygame.Surface((self.w, self.h))

class MainWindow(QWidget):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("PyQt6 + pygame Particle System")

        main_layout = QVBoxLayout()

        # widget-ul pygame – ocupă tot spațiul
        self.pg_widget = PygameWidget()
        main_layout.addWidget(self.pg_widget, stretch=1)

        # panou de controale jos
        control_panel = QVBoxLayout()

        # ----- slider spawn rate -----
        spawn_layout = QHBoxLayout()
        spawn_label = QLabel("Spawn:")
        self.spawn_value = QLabel("5")

        spawn_slider = QSlider(Qt.Orientation.Horizontal)
        spawn_slider.setRange(1, 50)
        spawn_slider.setValue(5)
        spawn_slider.valueChanged.connect(self.update_spawn_rate)

        spawn_layout.addWidget(spawn_label)
        spawn_layout.addWidget(spawn_slider)
        spawn_layout.addWidget(self.spawn_value)

        # ----- slider gravity -----
        gravity_layout = QHBoxLayout()
        gravity_label = QLabel("Gravity:")
        self.gravity_value = QLabel("0.10")

        gravity_slider = QSlider(Qt.Orientation.Horizontal)
        gravity_slider.setRange(0, 50)
        gravity_slider.setValue(10)
        gravity_slider.valueChanged.connect(self.update_gravity)

        gravity_layout.addWidget(gravity_label)
        gravity_layout.addWidget(gravity_slider)
        gravity_layout.addWidget(self.gravity_value)

        control_panel.addLayout(spawn_layout)
        control_panel.addLayout(gravity_layout)

        main_layout.addLayout(control_panel)

        self.setLayout(main_layout)

    def update_spawn_rate(self, v):
        self.pg_widget.spawn_rate = v
        self.spawn_value.setText(str(v))

    def update_gravity(self, v):
        g = v / 100.0
        self.pg_widget.gravity = g
        self.gravity_value.setText(f"{g:.2f}")

if __name__ == "__main__":
    app = QApplication(sys.argv)
    w = MainWindow()
    w.resize(1000, 800)
    w.show()
    sys.exit(app.exec())