5D.Rain

PURPOSE
Simulates falling rain.

INPUT CLIPS
Background: the clip to draw the rain on.
Birth Clip: the rain can optionally be created only within areas in this clip which are not black. This lets you restrict the source of rain to, say a cloud.
Bounce Clip: the rain can also optionally be made to 'bounce' when it reaches non-black areas in this clip. This can be used to make t he rain appear to bounce off objects in a scene.

Tips:

Rain is a time based effect; the characteristics a particle is born with, will evolve over time (every frame generated) to create the effect.

Jumping to a random frame will not show you the same result as when the sequence is generated sequentially.

Each particle is created with certain birth characteristics. On the frame they are born they are given:

lifetime
fadeout factor
an initial velocity and variance
a birth position ( the birth generation line )
a color (RGB) with variations (Color variance & Mono variance)

These factors are only changed by other forces acting on them.

animating the color will not change all the particles, only the particles that are born at that frame; but the color may fade over time depending on the Extinction factor.

the initial velocity causes the particles to move, but then gravity, wind; swirling, friction etc take effect.

Birth Limits: Particles can be born in an arbitrarily shaped region controlled by the intensity levels in the birth clip (which are 128 or greater) and the birth generation line (which should cross this region) if Use Matte Limits is on. If your control clip is not bright enough or your birth creation line misses the required area in the control clip, particle generation is stopped. Otherwise you would be forever trying to create a particle while the conditions for birth are not suitable.

Bouncing Rain: You can bounce the rain off a surface using the third input clip. The intensity level in the bounce clip must be greater than 0 (pure black) to activate the effect and Puddle Bounce must be turned On. The amount of bouncing is controlled by the Puddle Damping control.

TIME EDITOR CONTROLS

CREATION
Pre Roll Frames (Min: 1 Max: 1000 Default: 50)
How many frames to run the particle system before generating the first frame of the output clip if Do Preroll is selected.

Quantity (Min: 0.0 Max: 10000.0 Default: 10.0)
Average number of raindrops created per frame.

Extinction (Min: 1.0 Max: 1000.0 Default 180.0)
Number of frames over which a drop of rain will fade away.

To Live (Min: 1.0 Max: 1000.0 Default 80.0)
Number of frames of life after which a drop of rain will be destroyed.

POSITION
Radius (Min: 0.0 Max: 500.0 Default: 5.0)
Distance from the rain creation line within which rain will be created.

XY Left Position (Default: top left image)
XY Right Position (Default: top right image)
The ends of a line along which rain will be created. Imagine a line between the two points and an area around the line set be the Radius. Within this zone rain drop will be created. It can be off screen.

APPEARANCE
Streak Scale (Min: 0.1 Max: 500.0 Default:100.0)
Raindrops are always drawn as streaks (with a blob at the leading end, if they are glistening). (Streaks are anti-aliased lines). Normally, the streaks extend from the position of the drop in the last frame, to its position in this, getting denser along the path towards the current frame. This parameter lets the length of the streak be scaled from its normal length (distance covered between frames).

BOUNCE

Puddle Damping (Min: -200.0 Max: 200.0 Default: 10.0)
Controls the loss of velocity of a rain drop each time it bounces.

LIGHT
Glisten Tightness (Min: 0.0 Max: 1000.0 Default: 30.0)
Controls a region around the direction in which the light is shining, in which the drops will be given a glistening effect. This is the power to which a cosine is raised.

Minimum Brightness (Min: 0.0 Max: 100.0 Default: 60.0)
Sets the minimum brightness of a raindrop when drops are being lit by a light source but not within the main beam of light.

Intensity (Min: 0.0 Max: 200.0 Default: 100.0)
Sets the brightness of a light source illuminating the raindrops. If this is zero, the drops are treated as semi-transparent objects, and the lighting controls have no effect.

XY Target (Default: bottom center)
The point on the image, or beyond, at which the light is shining.

(Min: 0.0 Max: 180.0 Default: 180.0)
Angle of a cone within which the light is shining. The cone's axis is along the direction of the light. Outside the cone, the light intensity is zero. It reaches maximum intensity within 10% of the angle from the edges of the cone.

Source XY (Default: top center)
The point on the image, or beyond, from which the light is shining.

Red/Green/Blue (Default: white)
The light color.

FORCES

VELOCITY
Scale (Min: -80.0 Max: 80.0 Default: -5.0)
The initial speed of a rain drop. The direction is always in the direction of gravity.

Variance (Min: -100.0 Max: 100.0 Default: 5.0)
Size of random variations in initial speed of a raindrop. The direction is always in the direction of gravity.

GRAVITY
Strength (Min: 0.0 Max: 1000.0 Default: 100.0)
Scales the strength of the gravitational force.

Angle (Min : 0.0 Max: 359.0 Default: 270.0)
Controls the angle at which gravity acts, measured in degrees clockwise from due East. The default is towards the bottom of the image.

WIND
Speed (Min: 0.0 Max: 100.0 Default: 0.0)
The speed of the wind.

XY Target (Default: pointing to top right)
The point on the image at which the wind is blowing.

Spread (Min: 0 Max: 180.0 Default: 120.0)
Angle (in degrees) of a cone within which the wind blows. The wind has zero strength outside this cone, and reaches full strength inside a cone that is 10% smaller.

XY Source (Default: image bottom left)
The point on the image from which the wind is blowing.

SWIRLING
Density (Min: 0.0 Max: 100.0 Default: 0.0)
Number of turbulent bumps in the atmosphere across the frame. The raindrops can bump into these, causing them to swirl.

Amplitude (Min: 0.0 Max: 100.0 Default: 0.0)
Strength of the turbulent bumps in the atmosphere.

To Maximum (Min: 0.0 Max: 500.0 Default: 0.0)
The swirling of the atmosphere builds up from zero to its specified amplitude over this number of frames.

Friction (Min: 0.0 Max: 1.0 Default: 0.01)
Controls the frictional force of the atmosphere on the drops as a percentage of the drops velocity lost per frame. Slows the rain down.

RAIN COLOUR
Red/Green/Blue(Default: light blue)
The color given to the rain drops when they are created. Animating the colour will only change the colour of rain drops created at that time.

Colour Variance (Min: 0.0 Max: 100.0 Default: 0.0)
Random variation in the color of the raindrops.

Monochrome Variance (Min: 0.0 Max: 100.0 Default: 0.0)
Random variation in the brightness / density of the raindrops.

Intensity (Min: 0.0 Max: 400.0 Default: 60.0)
Initial intensity (or brightness) of a raindrop.

Condense (Min: 0.0 Max: 100.0 Default: 100.0)
When born, a raindrop can be transparent. This controls how quickly it becomes denser and more visible.

PI CONTROLS

restart
Restart the rain simulation, destroying all current raindrops first.

preroll
Run the particle system for the specified number of pre-roll frames before generating the first frame of the output clip.

RENDER PREROLL
This MUST be turned ON prior to rendering a sequence if you need the preroll effect. Rendering starts a completely new rainstorm; it cannot continue from where you currently are.

CLIP CONTROL
birth limits (Default: Off)
Off: uses only the position 'lozenge' to generate the rain particles.
On: uses the Birth clip to generate rain only if covered by the position lozenge.

bounce (Default: Off)
Off: ignores your Bounce clip.
On: bounces rain particles off the matte limits of the Bounce clip dependent on the Puddle Damping controls.

RENDERING
colour & density/colour/density (Default: colour & density)
These options affects how the raindrops composite with one another and with the background image and may have a great effect on the final appearance. For rain, using Density is usually best.

DEMOS
rain and drizzle
Set all rain parameters for a deluge or a drizzle.

5D.Rain

Index