# Common module
# Overview
Common (Common module of particle system), used to set the initial attribute values of particles, such as initial velocity, rotation, color, life time, etc.
# Property description
| Property | Function | Type |
|---|---|---|
| startLifeTime | The life time of the particle. | number |
| scalingMode | Scaling mode. | engine.Particle.ParticleCommon.ScalingMode |
| Hierarchy | Indicates that the size of the particle is affected by the superposition of the zoom value of itself and all parent nodes. (For 2d particles, the particle size will be affected by the design width and height, you need to set transform2D.scale to a larger value to display) | engine.Particle.ParticleCommon.ScalingMode.Hierarchy |
| Local | Local means that the size of the particle is only affected by its own zoom value. ** (For 2d particles, the particle size is not affected by the design width and height changes, and the particle size value is directly set to the clipping space) ** | engine.Particle.ParticleCommon.ScalingMode.Local |
| Shape | Shape means that the size of the particle is not affected by the zoom value of itself and its parent node. ** (For 2d particles, the particle size is not affected by the design width and height changes, and the particle size value is directly set to the clipping space) ** | engine.Particle.ParticleCommon.ScalingMode.Shape |
| simulationSpace | The space where the simulation particles are located. | engine.Particle.ParticleCommon.SimulationSpace |
| Local | The particles are in local space. | engine.Particle.ParticleCommon.SimulationSpace.Local |
| World | The particle is in world space. | engine.Particle.ParticleCommon.SimulationSpace.World |
| startSpeed | The initial speed of each particle. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startSize3D | Whether to enable the size settings in the three directions of XYZ. | boolean |
| startSize | If startSize3D is false, the initial size of each particle. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startSizeX | If startSize3D is true, the initial size of the particle in the X-axis direction. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startSizeY | If startSize3D is true, the initial size of the particle in the Y-axis direction. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startSizeZ | If startSize3D is true, the initial size of the particle in the Z-axis direction. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startRotation3D | Whether to enable the rotation settings in the three directions of XYZ. | boolean |
| startRotation | If startSize3D is false, the initial rotation angle of each particle. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startRotationX | If startSize3D is true, the initial rotation angle of each particle on the X axis. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startRotationY | If startSize3D is true, the initial rotation angle of each particle on the Y axis. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startRotationZ | If startSize3D is true, the initial rotation angle of each particle on the Z axis. | engine.Particle.AdvancedProperty.ConstantProperty engine.Particle.AdvancedProperty.TwoConstantsProperty engine.Particle.AdvancedProperty.CurveProperty engine.Particle.AdvancedProperty.TwoCurvesProperty |
| startColor | The initial color of each particle. | engine.Particle.AdvancedProperty.OneColorProperty engine.Particle.AdvancedProperty.TwoColorsProperty engine.Particle.AdvancedProperty.GradientProperty engine.Particle.AdvancedProperty.TwoGradientsProperty |
Notice:
For 2d particles, the size attribute of transform2d will not have any effect on the particle size. The scaling of 2d particles depends on the scalingMode attribute in the common module. When scalingMode is Local and Shape, the particles are not affected by the world matrix, so they will not change with the design width and height, and directly enter the clipping space. When scalingMode is Hierarchy, the particles will be affected by the world matrix, because the 2d world matrix will be scaled according to the design width and height, so the scale property of transform2D needs to be set to a corresponding multiple to see the particles.