// Copyright (C) 2019 Klaralvdalens Datakonsult AB (KDAB). // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only import Qt3D.Core 2.14 import Qt3D.Render 2.14 import Qt3D.Extras 2.14 import Qt3D.Input 2.14 Entity { property alias computeMode: particlesComputeJob.runType function triggerCompute(frames) { particlesComputeJob.trigger(frames) } components: [ RenderSettings { ComputeFrameGraph { camera: sceneCamera } // explicitly set RenderingPolicy to AlwaysRender, as changes in the // scene won't be reflected in actual Qt scene-graph changes (due to // GPU compute calls) renderPolicy: RenderSettings.Always }, InputSettings {} ] FirstPersonCameraController { camera: sceneCamera } Camera { id: sceneCamera projectionType: CameraLens.PerspectiveProjection viewCenter: Qt.vector3d(0, 0, 0) position: Qt.vector3d(0, 20, -800) nearPlane: 0.1 farPlane: 1000 fieldOfView: 60 } property int particlesCount: 1024 * 1024 readonly property int floatSize: 4 function buildParticlesBuffer() { var byteSizeOfParticleData = 8; var bufferData = new Float32Array(particlesCount * byteSizeOfParticleData); for (var x = 0; x < 1024; ++x) { for (var z = 0; z < 1024; ++z) { var i = x * 1024 + z; var positionIdx = i * byteSizeOfParticleData; var colorIdx = i * byteSizeOfParticleData + 8; bufferData[positionIdx] = -1024 + x * 2; bufferData[positionIdx + 1] = 0; bufferData[positionIdx + 2] = -1024 + z * 2; bufferData[positionIdx + 3] = 1.0; bufferData[colorIdx] = 0.25 + Math.sin(x / 1024) * 0.75; bufferData[colorIdx + 1] = 0.25 + Math.sin(z / 1024) * 0.75; bufferData[colorIdx + 2] = 0.25 + Math.sin(x / 1024) * 0.75; bufferData[colorIdx + 3] = 1.0; } } return bufferData } Buffer { id: particleBuffer // struct ParticleData // { // vec3 position; // Aligned to 4 floats // vec3 color; // Aligned to 4 floats // }; data: buildParticlesBuffer() } Attribute { id: particlePositionDataAttribute name: "particlePosition" attributeType: Attribute.VertexAttribute vertexBaseType: Attribute.Float vertexSize: 3 divisor: 1 byteStride: 8 * floatSize buffer: particleBuffer } Attribute { id: particleColorDataAttribute name: "particleColor" attributeType: Attribute.VertexAttribute vertexBaseType: Attribute.Float vertexSize: 3 divisor: 1 byteOffset: 4 * floatSize byteStride: 8 * floatSize buffer: particleBuffer } ComputeMaterial { id: computeMaterial dataBuffer: particleBuffer } ComputeCommand { id: particlesComputeJob onRunTypeChanged: { // Don't forget to re-enable the command // when switching back to continuous if (runType === ComputeCommand.Continuous) enabled = true } } Entity { id: particleComputeEntity components: [ particlesComputeJob, computeMaterial ] } SphereGeometry { id: sphereGeometry rings: 10 slices: 10 radius: 1 // Additional Attributes attributes: [ particlePositionDataAttribute, particleColorDataAttribute ] } Entity { id: particleRenderEntity readonly property GeometryRenderer particlesRenderer: GeometryRenderer { instanceCount: particlesCount indexOffset: 0 firstInstance: 0 primitiveType: GeometryRenderer.Triangles geometry: sphereGeometry } components: [ particlesRenderer, computeMaterial ] } }