[Kool]

Hi guys,

I have in total around 300 entities in my scene. All of these entities need to have a ParticleVPlay, because each one can die somewhere in the scene and needs to ‘explode’ at that point.

I’ve noticed that having 100+ ParticleVPlay has a major effect on FPS. The CPU and RAM usage shoots right up and I’m unsure as to why. I’ve reproduced this with the following example (you may need to substitute the json with your own):

import Felgo 3.0
import QtQuick 2.0

GameWindow {
    id: gameWindow

    activeScene: scene

    screenWidth: 960
    screenHeight: 640

    EntityManager {
        id: entityManager
        entityContainer: scene
    }

    Scene {
        id: scene

        // the "logical size" - the scene content is auto-scaled to match the GameWindow size
        width: 480
        height: 320

        Repeater {
            model: 300

            ParticleVPlay {
                id: particles
                fileName: "explosion_blue.json"
                autoStart: false
                running: false
            }
        }

        PhysicsWorld {
            debugDrawVisible: true
        }

        Rectangle {
            color: "black"
            anchors.fill: parent
        }

        Rectangle {
            width: 100
            height: 25
            color: "white"
            anchors {top: parent.top; right: parent.right}

            Text {
                text: "Move"
                anchors.centerIn: parent
            }

            MouseArea {
                anchors.fill: parent
                onClicked: scene.move()
            }
        }

        function move() {
            player.y = 0;
            player.move()
        }

        EntityBase {
            id: player
            width: 25
            height: 25
            x: scene.width/2 - player.width
            y: 0

            Rectangle {
                anchors.fill: parent
                color: "red"
            }

            BoxCollider {
                id: collider
                bodyType: Body.Dynamic
            }

            MovementAnimation {
                id: animation
                target: parent
                property: "y"
                velocity: 100
                maxPropertyValue: scene.height - player.height
                onLimitReached: y = 0
            }

            function move() {
                animation.start()
            }
        }
    }
}

Press the top right button to start moving the entity. Even though the particle effects aren’t being started, the FPS has dropped dramatically. Whilst it’s running, notice the high CPU and RAM usage.

If you change the repeater model value to 10, it’s usable again.

Any suggestions to achieve what I need?

Thanks!

[GüntherFelgo Team]

Hi Kool!

The ParticleVPlay type is based on the Qt Particle System and combines types like ParticleSystem, Particle and Emitter. This implementation is easy to use but might not be the best in performance if a big amount of particles is used. For example, each ParticleVPlay instance defines its own ParticleSystem which means 300 independent systems with particle emitters in your case.

To achieve a better performance with many particles, you can try directly using these standard QML Particle types for your particle implementation. You could then use a single ParticleSystem that holds multiple particle emitters for your effects to get the best performance possible with the Qt types.

 

Also, as I guess not all the Particles will be triggered at the same time, you could try to reduce the amount of active ParticleVPlay items. For example by creating and removing the ParticleVPlay items dynamically when they are needed. Another idea would be to hold a smaller pool of ParticleVPlay items that you position and start whenever an effect should be shown (so your entities share and use a fixed bool of particle items).
Best,
Günther

 

 

[AlexFelgo Team]

Here is a set of good tutorials for using the standard Qt particles: https://qmlbook.github.io/en/ch08/index.html

Cheers,
Alex

[Kool]

Thanks for the advice.

I’ve opted to create 10 particle effects and move their positions around the screen as required.