# Using HGE Particle Systems Editor interface ## General information and controls Use the left mouse button in the black area to fire the particle system. Hold the right mouse button down to make the particle system follow the mouse. Use keys 1 to 9 for fast switching between presets. The presets are saved and loaded automatically. The Escape key quits the editor. Use TAB to hide interface and SPACE to run particles preset. The most of particle system parameters are controlled with a group of sliders. There are two basic control schemes. A min/max sliders pair that define a constant range for the respective parameter. And a group of strt/end/var sliders, defining the starting value, the ending value and the starting value variation within the range between the strt and end. Use the lock buttons () to constrain the min/max or strt/end parameters to the same value. All the rest controls are rather common and shouldn't make a challenge for you. ## System Parameters This group of parameters define the whole particle system behaviour: System lifetime Defines the period of time when the particle system generates new particles. If the continuous check box is activated - the particles are generated all the time. Emission Defines how much new particles are generated per second. Particle lifetime Defines the period of time during which a specific particle is alive. Texture Specifies one of the 16 sprites to be used for the particles. Blend mode Specifies the particles' blending mode: additive - a particle color is added to the graphics already on the screen resulting in lighting effect, blend - a particle color is blended with the graphics already on the screen. ## Particle Movement This group of parameters define the movement of a specific particle: Direction This is an angle, defining particles emitting direction. If the relative check box is activated - the angle is treated relative to the current particle system's movement direction. Spread This angle defines the sector within which the particles are emitted. For example, if it is 40, the emitted particles direction lies within Direction-20 and Direction+20. If the Spread is 360, the Direction parameter becomes meaningless as the whole circle is covered. Start speed Defines the range of starting speed for the particles. Gravity Defines the range of gravity values for the particles (basically, it is just an acceleration along the Y-axis). Radial acceleration Defines the range of values for the acceleration directed towards the particle system's center. Use this to create particle system that attracts the particles to it's center. Tangential acceleration Defines the range of values for the acceleration directed perpendicularly to the radial acceleration. Use this to make particles rotate around the particle system's center. ## Particle Appearance This group of parameters define the appearance of a specific particle: Particle size Defines the starting and ending size of a specific particle and it's starting size variation. Note that bigger particles require more time to render. Particle spin This parameter defines the speed of a specific particle rotation around it's anchor point. Set the starting and ending rotation speed and it's starting rotation speed variation. Particle alpha Defines the starting and ending opacity of a specific particle and it's starting opacity variation. Particle color Defines the starting and ending color of a specific particle and it's starting color variation. ## Presets & Stuff Under this name various editor's information and commands are placed: Preset No. Use this set of buttons to switch between the particle system presets. Presets are saved and loaded automatically in files named particle1.psi - particle9.psi. Show bounding box If this check box is activated, the particle system bounding box is displayed. So you can adjust parameters to make the whole particle system fit into the desired dimensions. Note that during bounding box calculation the particle positions only are considered, and the particle sprites' dimensions are ignored. Particles alive Shows how much particles are currently alive. Try to keep this value as small as possible, because it affects your application performance. The two parameters that affect this value is Emission and Particle lifetime. FPS Shows the current frames-per-second rate.