Particle Object

Allows the creation of custom particle effects tied to objects.

Particle Editor

Particle properties can be edited from the Particle Editor accessible from Edit Special.

The editor is split into 4 main tabs (Motion, Visual, Extra & Texture) with an interactible preview on the bottom left side of the menu.

The Texture tab selects the particle's texture.

Randomization

Most particle variables can be randomized in a range using a +- variable found next to the base one.

Copy Paste

C and P can be used to copy & paste the particle settings between different particle objects. Copied settings are lost when exiting the editor.

Interactible Preview

Previews the current particle effect. The preview is interactible and can be used to pan around or change some particle effects by touch.

Options 1, 2 and 3 change what settings are being edited by touching the preview. Only one can be active at a time, and if none are selected dragging pans the preview. Options can be deselected by clicking them once again.

Options edit different settings for Gravity and Radius modes, these are:

Gravity

• Option 1: PosVar X & PosVar Y (rendered as green rectangle)
• Option 2: Gravity X & Gravity Y (cyan line) -Option 3: Speed & Angle (yellow line, angle random is represented as a yellow semicircle but is not edited)

Radius

• Option 1: StartRad (green semicircle)
• Option 2: EndRad (orange semicircle)
• Option 3: Angle (not represented, all options render at once, semicircle arc depends on angle random, if 0 none render)

Two more buttons, C and a color box affect the preview box. C recenters the screen back to the particle's origin, the preview's background color can be set from the preview box - it is black by default and is reset when closing the menu.

Motion

Particle settings that affect motion and emission behavior. Two motion modes are available - Gravity and Radius.

Common

Max Particles is the max amount of particles that can be active at once, any further particles will fail to spawn.

Duration is the amount of time the emitter spawns particles. The emitter spawns particles until Duration runs out, and once the lifetime of all remaining particles expires then the emitter despawns and is replaced by another emitter by the particle object. Duration is infinite if set to -1 so the emitter will not stop spawning particles unless the particle object is unloaded. If value is 0 particles will not spawn unless Emission is -1.

Lifetime is the lifetime of the particle.

Emission is the amount of particles that can spawn per second. Emission also delays the first particle spawn by $1/Emission$ seconds, if the delay is bigger than Duration then no particles will spawn. If Emission is -1 then emission is infinite - the emitter will try to respawn all particles every frame without delay. Max sets Emission to -1, Calc calculates Emission using the formula $MaxParticle/(Lifetime+LifetimeRand)$.

Angle is the starting angle of the particle's motion. The value is given in degrees with 0 pointing right, positive values offset the angle clockwise and negative ones offset counter-clockwise.

Gravity

Speed is the particle's starting velocity, given in units (small steps) per second. All acceleration settings change the particle's velocity by $accel/100$ units per second.

PosVar X and PosVar Y give a range in units that randomize the particle's offset on the X and Y axis from the emitter's origin.

Gravity X and Gravity Y applies acceleration on the X and Y axes towards positive values, negative values accelerate away from positive and towards negative instead.

AccelRad applies acceleration away from the emitter's origin for positive values and towards the origin for negative ones.

AccelTan applies acceleration tangential to the particle's current direction, positive values accelerate clockwise while negative ones counter-clockwise.

AccelRad and AccelTan are not applied if velocity is null.

Radius

StartRad and EndRad are the radial distances in units the particle starts from and ends at respectively. This movement is unaffected by FrictionP.

RotSec is the amount of degrees per second by which particles rotate around the emitter's center. Rotation is done in whole degree increments, so at low values the rotation is choppy.

Visual

Particle settings that affect scaling, rotation and color (RGBA) values.

Scale & Rotation

StartSize is the particle's initial scale, while EndSize is its final scale. Scale 16 is equivalent to the scale of the object variant of the particle.

StartSpin is the initial rotation of the particle texture, while EndSpin is its final rotation. This rotation offsets texture rotations done by Start Rot is Dir and Dynamic Rotation.

Colors

Start and End RGB values for the particles can be set in two ways:

• Using the two color pickers found on the top left of the menu
• Individual Start and End variables for each color channel, normalized to 1.00 (Start_R, Start_B, Start_G, End_R, End_B, End_G)

The <> button next to the color selectors copies the main color to the secondary color. Changing the color from the color picker updates the RGB variables instantly, but changing the RGB variables updates the colors from the picker only when you reopen the particle editor. Particle objects store RGBA as normalized values with 1% accuracy, rounding to the nearest value when converted to 8-bit RGBA.

Alpha cannot be set from the color picker, it can only be edited using the two Start_A and End_A variables.

Extra

Miscellaneous particle settings and extra options that do not fit in other tabs.

Free, Relative & Grouped

Free, Relative and Grouped change what point of reference the particles are relative to (camera, world, object)

• Free makes the particles copy the camera's movement and the opposite of the object's movement (particles appear relative to camera).
• Relative makes the particles copy the opposite of the object's movement. (particles appear relative to world).
• Grouped is default and applies no extra movement (particles appear relative to emitter).

How the particle object's scaling and rotation affects the spawned particles is different between Free / Relative and Grouped:

• With Grouped, the particle object can be scaled and rotated like normal.
• With Free & Relative, the game adds a special property to the particle object when you save the level which makes particles ignore the object's scale, warp and rotate; ignore rotations done by rotate triggers; if scaled by a trigger, scale the particles by either X or Y scale, whichever is smaller (but not equal to 1).

This may appear inconsistent when testing in the editor, because the particle is updated only when re-entering the editor.

Particle objects can be warped and skewed and this will warp the emitter, but if the object was already warped before the emitter is created, then the emitter will not have the object's warping.

Fade, Friction & Respawn

Fade In and Fade Out add fades to the start and end of particles.

Min fade duration is 0, while max duration depends on the lifetime - Fade In is limited by the particle's lifetime, while Fade Out is limited to whatever time is left after Fade In. Both fades stack together with alpha.

There are 3 unique friction values that each affect one of the particle's transformations:

• FrictionP (velocity)
• FrictionS (scale)
• FrictionR (rotation)

All three friction settings can be approximated by an exponential decay function optimized for different frame rates:

$Gradient=Gradient\cdot exp(-Friction\cdot FrameDelay)$.

For FrictionP gradient is speed, for FrictionS gradient is $(EndScale-StartScale)/Lifetime$ and for FrictionR gradient is $(EndSpin-StartSpin)/Lifetime$. Frame delay is truncated to 4 decimals, since the friction required to match Advance Follow is ~2.44 to 1.00.

FrictionP is only applied to gravity mode, FrictionR is only applied to spin and not Dynamic Rotation.

Respawn is how long it takes for a particle object to respawn an emitter with a finite Duration after the current one expires.

Misc Settings

Additive makes particles blend. Also works for Use Obj Color and Uniform Obj Color in some cases, but changes how alpha is calculated in a non-intuitive way.

Start Size = End increases the particle's end size by its start size. This is particularly useful if StartSize is randomized and you want the particle to change or keep its end size relative to it.

Start Spin = End does the same thing for spin (rotation) and Start Rad = End does the same for radius.

Start Rot is Dir makes the particle's rotation match its start Angle.

Use Obj Color makes the particle use the particle object's colors instead of the emitter's RGB values. These colors are set at the creation of each particle and do not update if the parent object changes color. Base RGB variables are ignored, but RGB can still be randomized using the +- options.

Uniform Obj Color makes the particle copy the particle object's colors dynamically. All particle color options besides alpha are ignored.

Dynamic Rotation makes the particle rotate dynamically in the direction of movement.

Animate On Trigger allows activating the particle object with an Animate trigger. Animated particle objects start inactive until activated by Animate Trigger, any remaining particles still connected to the target object are also cleared.

If Duration is infinite, the particles will continue to spawn indefinitely as long as they are active, otherwise they will spawn once without looping.

Inactive particle objects are ignored if they have the Only If Active property.

Order Sensitive makes newer particles from the same emitter layer above older ones, without this option the layering / render order is randomized.

StartRGB Var Sync and EndRGB Var Sync replace Start and End RGB randomization with lightness randomization (brightness and saturation only are randomized) - the R channel Start_R +- and End_R +- options are used to randomize lightness, B and G random options are ignored.

Quick Start makes the particle skip simulating the first 2 seconds when starting if Duration is infinite. A particle with Quick Start still connected to its parent object will persist to the next attempt, even if resetting all checkpoints.

Misc Behavior

Particles animate by frame, not by tick. Visuals are going to differ between devices with different framerates - particles with very high emissions will not look as smooth on lower framerates and have more clumps if not randomized.

Particles have a softcap of 100k particles active at once, if the softcap is hit any further particle objects that become active will not spawn particles until reloaded. The softcap can be passed by an emitter that goes over the limit. The total particle count is calculated based on the emitter's max particle property, not its current particle count, so avoid oversizing the value of max particle. The particle softcap is not used in the level editor.

Particle objects do not unload correctly in normal mode, but they do in the editor. Emitters tied to particle objects are not cleared if the object is unloaded, and continue being active until they despawn on their own. These emitters are disconnected from the object that created them, so any particle setting that depends on the parent object will stop updating. When the particle object becomes active again, it will create a new emitter separate from the previous one.

Alpha & Blending Behavior

Alpha values are calculated differently depending on the options selected, below you can find a table approximating these calculations.

Additive	Obj Color	Uniform Color	Blending	Solid Alpha	Blending Alpha
No	No	No	Either	$(start\cdot (1-t)+end\cdot t))\cdot base$	-
No	No	Yes	No	$(start\cdot (1-t)+end\cdot t)\cdot base$	-
No	No	Yes	No	$(start\cdot (1-t)+end\cdot t)\cdot base$	-
No	Yes	No	No	$(base\cdot (1-t)+end\cdot t)\cdot base$	-
No	Yes	No	Yes	-	$(bas{e}^2\cdot (1-t)+end\cdot t)\cdot bas{e}^2$
Either	No	Yes	Yes	-	$(start\cdot (1-t)+end\cdot t)\cdot bas{e}^2$
Yes	Yes	No	No	$(base\cdot (1-t)+end\cdot t)\cdot base$	$((1-base)\cdot (1-t)+(1-end)\cdot t)\cdot base$
Yes	Yes	No	Yes	-	$(base\cdot (1-t)+end\cdot t)\cdot bas{e}^2$
Yes	No	No	Either	-	$(start\cdot (1-t)+end\cdot t)\cdot bas{e}^2$
Yes	No	Yes	No	$(start\cdot (1-t)+end\cdot t)\cdot base$	$((1-start)\cdot (1-t)+(1-end)\cdot t)\cdot base$

Notes:

• $start$ is the initial alpha, equal to: $Start\text{\_}A+Start\text{\_}A\text{\_}Rand$
• $end$ is the final alpha, equal to: $End\text{\_}A+End\text{\_}A\text{\_}Rand$
• $base$ is the alpha (opacity) of the base color channel.
  • The detail color channel's opacity is not used by particles.
  • Use Obj Color replaces $start$ with $base$ in all calculations.
  • $base$ is applied multiple times in some equations.
• For a particle to count as blending either the base or detail color must be blending.
  • If Use Obj Color or Uniform Obj Color are used with Additive but neither color channels blend, then the particle renders as both normal and additive.
• The resulting color for one particle is equal to: $BG\text{\_}RGB\ast (1-Solid\text{\_}Alpha)+Particle\text{\_}RGB\ast (Solid\text{\_}Alpha+Blending\text{\_}Alpha)$