- Requires LightWave 6.5b with LScript 2.2.2.
- Should work on both Mac and PC. Mac users please let me know if you have trouble.
- Slight changes to documentation.
- Works with LightWave 6.5b (LScript 2.2)
- Because my original interface code doesn't work properly with LScript 2.2, the interface is not as pretty or as slick as it used to be (not that it was very pretty or slick to begin with).
- No functionality was added or removed.
- Slight changes to documentation.
- Super Spinner was spinning basic SLA and SLM rigs too much. Thanks to Terry Naas for pointing this out.
- Super Spinner is now a compiled Run-Time LScript which allowed me to include some helpful graphics on the Make SLA Rig panel. You must have LScript 2.1.1 to use this version of Super Spinner. Use LW_LScript/RT to run it. Mac users see note below.
- Super Spinner now uses 3 keyframes to control repeating animations. This should ensure proper repetition in every frame no matter the blur length.
- Added support for Blur Type.
- The patterns for SSH and SSF rigs have been improved.
- Documentation has been updated and now includes graphic examples.
Thanks to everyone who provided feedback!
Note to Mac users: I used to think that Mac versions had to be compiled on a Mac. Apparently this is not the case. LScripts compiled on the PC should work on the Mac, but there was a bug that was preventing this. That bug was supposedly fixed in LScript version 2.2.2, so Beta version 04 should work with both Mac and PC. Mac users please let me know if you have trouble.
Super Spinner 1.0 Documentation revC
© Dug
Stanat, 2001
www.dugosaurus.com
dug@dugosaurus.com
Table
of Contents
Quick Start
Introduction
Running Super Spinner
Super Spinner Main Panel
Make SLA Rig (Spinning Light Automatic)
Make SLM Rig (Spinning Light Manual)
Make LAR Rig (Light Array)
unSpin Rig
reSpin Rig
Optimize Scene
Information
Exit
Important Notes
Tips on Understanding the
Different Rig Types
Tips on Rig Adjustment
Tips on Makin' Purty Shadows
FAQ
Quick Start
To start using Super Spinner, just do the following:
• Make sure
you have LScript 2.1.1 or later installed and the appropriate version of Super
Spinner.
• Open Layout, load an object or two so you have something
to cast shadows.
• Make the default light a spotlight casting Shadow-Mapped shadows with
a Shadow Fuzziness of 4.
• Run LW_LScript/RT and select super_spinner.lsc (mac users run LW_LScript
and run super_spinner.ls).
• Choose "Make SLA Rig" and press OK. Apply options as scene
in Figure 1, with the exception that you need to make sure the arm length (in
meters) is reasonable considering the distance between the light and the objects
you've loaded.
Figure 1: "Make SLA Rig" panel. Mac users will not see the graphic (the look of this panel changed slightly in Beta 03).
• Click OK and then click OK again on the main menu to exit Super Spinner. Your original light has now been replaced by a "Spinning Spiral Full" (SSF) light rig which will cast a light pattern as seen in the SSF graphic in Figure 01, where each color represents a different light (the colors are for illustration purposes; the lights themselves will be whatever color your original light was).
There, now you are up and running with Super Spinner. Hit F9 and render a frame. Those 3 lights will cast 15 shadows that (hopefully) will appear as one soft shadow.
Introduction
Several years ago Dave Jerrard wrote an excellent tutorial entitled The Amazing Spinning Light Trick. It introduced many LightWave users to the technique of spinning a light around a parent null to create soft shadows. The technique takes advantage of the way LightWave renders motion blur. When motion blur is on, LightWave renders multiple passes for each frame and then composites them together to give you a final render. Anything that moves while the camera's virtual shutter is open will be rendered differently in each pass, and thus will appear blurred when the final frame is composited. How successful the effect is depends on a number of factors. If an object is moving very quickly, many passes are necessary to achieve an acceptable result. The number of motion blur passes is governed by level of antialiasing (low = 5, medium = 9, high = 17, extreme = 33, and the dithered option essentially doubles the number of passes).
So the spinning light trick causes a single light to cast multiple partial-strength shadows in each frame, thus creating a soft-shadow effect. Dave Jerrard's tutorial included render time comparisons of spinning shadow-map lights versus static area lights and it was easy to come to the conclusion that in many situations a shadow-map spinning light was a much better choice than an area light. In fact, if a final render uses motion blur, soft shadows from a spinning light should not add anything to your render time. Free soft shadows...that is pretty cool!
Basic Spinning Light Anatomy
A
very basic spinning light rig consists of 2 nulls and a light, parented in the
following hierarchy:
pointer / spinner / light
The pointer null positions and rotates the whole rig. Place it as you would a light.
The spinner's position always remains the same (0,0,0) so it sits directly on the pointer. The spinner's heading and pitch are kept at zero. But the spinner's bank rotation is keyframed to do the same task over and over: rotate 360 degrees every time the camera's shutter is open. The default camera motion blur is 50%, which means the camera's shutter will be open during the last half of each frame. If we want the spinner null to rotate 360 degrees while the virtual shutter is open, we can either set a keyframe value of 720 degrees at frame 1 (value = 360/blur_length) or set a keyframe value of 360 degrees at frame .5 (frame = blur length). Either way will yield the same result, as long as you remember to set the bank channel's pre- and post-behaviors to repeat. These channel behaviors will cause the spinner to do the same thing, over and over, every frame. It is this consistent repetition that gives you the illusion that the light is stationary rather than spinning like a dervish...
Now for the position of the light itself. Being parented to the spinner, the light is now spinning. Without any position or rotation change, though, the shadows will all be cast from the same point. Multiple shadows can be created by giving the light a positional offset and/or an angle offset at keyframe 0. Super Spinner makes the offsets on the Y and Pitch, but X and Heading would work, too. Now as the rig spins, the light revolves around the the pointer, and multiple shadows are cast during each motion-blurred render. Note that positional offsets are irrelevant to distant lights, while angle offsets are irrelevant to point lights (and somewhat irrelevant to spot lights...see Tips on Makin' Purty Shadows).
The spinner doth rotate too much, methinks
But wait, back up. There is a problem with our basic setup. Spinning a light 360 degrees while the shutter is open is actually too much. 360 degrees results in 2 samples being taken at exactly the same place. Take the example of rendering frame 1 with 50% motion blur and low antialiasing. The camera will take 5 samples, stepping backwards from the current frame (frame 1) to halfway between the current frame and the previous frame (frame 0). Thus the first sample will be taken at frame 1. The next samples at frames 0.875, then 0.75, then 0.625, and finally at frame 0.5. For the first and last samples the light will be in exactly the same space because at the first sample the light is banked to 0 degrees and in the last sample the light is banked to 360 degrees. Thus we get light cast from 4 positions instead of 5, with one position being twice as bright as the others. To combat this, one can either decrease the motion blur or decrease the spin amount. To get evenly spaced shadows, Super Spinner decreases the spin amount by using the following equation:
spin amount while shutter is open = 360 * (# of AA samples - 1) / (# of AA samples).
Thus with the previous example, while the shutter is open the light should spin: 360 * 4 / 5 = 288 degrees.
AA samples are as follows: Low = 5, Medium = 9, High = 17, Extreme = 33. Note that Dithered Motion Blur effectively doubles the number of samples.
If you have never used a spinning light before, take the time now to set one up and get it working. Understanding the basic setup will help you get the most out of Super Spinner.
Basic Rules of Spinning Lights
The primary rule of spinning lights is that the light's shadow-casting motion will occur not during the course of a frame, but during the course of each exposure (a fraction of the frame governed by the camera's blur length).
The next rule is that if the shadows are to appear static, the movement must be exactly the same during each exposure. Usually this is accomplished by repeating the same motion every frame.
Aside from that, there aren't really any rules. Spinning a light in a complete circle during one exposure is not even necessary (perhaps you want your light to cast shadows from an arc, rather than a symmetrical circle). Furthermore, who says you have to spin your lights at all to take advantage of the spinning light trick...
Beyond Spinning Lights
The spinning light trick is all about moving your lights repetitively during each exposure. You can attain soft shadows by moving your lights in ways other than spinning. Moving lights forward during exposure, which I call z-slip, can be very effective, particularly with large arrays of lights. With the ability to make fractional keyframes, you could have a light array complete a complex path during every exposure, simulating a general area from where light is cast. One obvious limitation to this technique is that shadows cast by fast moving objects will appear strange. This is because during each motion-blur pass both the light and the object will be in different positions. But if your animation does not include very fast animation, employing these techniques with large arrays can be very practical, as a large spotlight array with shadow maps rather than raytracing can rendering surprisingly quickly. And that is why...
It Slices, it Dices...
Super Spinner does a whole lot more than just turn a light into a spinning light. Super Spinner can turn a single light into a spinning rig with up to 26 lights. Or into a light array with up to 26x26 lights. Super Spinner makes 5 different rig types, and each can be rigged, unrigged and rigged again in seconds. When you rig a light, the light's motion, parent, and children and are passed to the root of the rig (the pointer null). Then when you unrig the light, the light re-inherits the pointer's motion, parent, and children. Furthermore, when you rig a multi-light rig, the light intensities (or intensity envelopes) are adjusted so that the overall light intensity remains the same. All these features mean you can quickly move between rigged and unrigged lighting with minimal hassle. Finally, Super Spinner provides some scene management tools that make life with spinning lights easier, especially when changing frame rates, antialiasing, and motion blur settings.
I was hoping for LW 6 that Newtek would create some cool new light types that cast fast soft shadows. Sure, radiosity is pretty cool and area lights can look pretty nice, but neither are very practical for animation. I think Newtek could've spent a tiny fraction of the energy expended on radiosity to give us some cool, practical, soft shadow tools. But they didn't. Perhaps they will for the next version. Until then, or until you buy Shadow Designer (which looks pretty cool), there is Super Spinner, which hopefully is a cool, practical, soft shadow tool...enjoy.
Running Super Spinner
Super Spinner 1.0 is a Run-Time Generic LScript for Layout that requires LScript 2.1.1 which is a fix for LScript 2.1 (LScript 2.1 was released with LW 6.5. You can download LScript 2.1.1 at Newtek's site).
You can run Super Spinner from Layout by going to the Scene tab, pressing the LScript menu button and selecting LW_LScript/RT. Then select super_spinner.lsc and it will run. Or you can load Super Spinner as you would a regular plugin, thus giving you access to Super Spinner in the Plugin Options panel under the Generics button, as well as allowing you to assign Super Spinner to a keystroke or menu button.
Note to Mac users: I could not get the compiled version of Super Spinner to run on a Mac, so the Mac version is an uncompiled Generic LScript. Instead of using LW_LScript/RT, use LW_LScript to run Super Spinner (or load it as a plugin). All functionality should be identical to the compiled version but you will not see the graphic on the "Make SLA" panel.
Be sure to turn off "Parent-In-Place" in the General Options panel (o) before running Super Spinner! Also, as good practice dictates, save your scene before running Super Spinner.
Super Spinner Main Panel
When you run Super Spinner, the first thing you will see is the main panel with eight options.
Make
SLA Rig (Spinning Light Automatic)
Make SLM Rig (Spinning Light Manual)
Make LAR Rig (Light Array)
unSpin Rig
reSpin Rig
Optimize Scene
Information
Exit
Choosing an option and clicking OK will initiate that option. You can quit by either pressing Cancel or by selecting the EXIT option and pressing OK. Note that pressing Cancel will NOT undo any actions you've already taken while running Super Spinner.
Figure 2: Super Spinner Main Panel (the look of this panel changed substantially in Beta 03).
Make SLA Rig (Spinning Light Automatic)
This option creates an SLA (Spinning Light Automatic) with up to 26 lights. If you're unsure of which type of rig to create, make an SLA. There are two subtypes of SLAs. Spinning Spiral Full (SSF) and Spinning Spiral Half (SSH). See Tips on Understanding the Different Rig Types to understand the patterns these rigs cut.
Anatomy of an SLA
Pointer null: This is the root of the rig and as such the pointer inherits the light's parent, children, and motion. Any procedural motion or plugin motions WILL NOT be inherited and must be assigned manually. Adjust the position and rotation as you would when placing a light.
Spinner null: A child of the pointer, the spinner's bank causes the rig to spin. As seen in Figure 3, three keyframes are used, one at frame -1 (a), one at frame -blur length (b), and one at frame 0 (c). Frame (a) to (b) is flat at 0 degrees (frame (b) is given a "Stepped" incoming curve). All the rotation happens from (b) to (c).
Figure 3: Three keyframes on the spinner Bank channel.
For basic SLAs, the amount of spin depends on the number of motion blur samples and the number of lights in the rig. Unlike basic SLAs, SSH and SSF rigs depend only on the number of lights in the rig because their changing arm lengths prevent 2 samples from being taken from the same location (see The spinner doth rotate too much, methinks).
This makes evident one of the advantages to the spinning spiral rigs. When you change antialiasing levels or blur type (normal or dithered), no adjustment is necessary for SSH and SSF rigs. Please note that every rig should be adjusted (using the Optimize Scene option) when FPS or camera blur lengths are changed.
Offset nulls: Children of the spinner, there will be one offset null for each light in the rig. The offset nulls are static, but rotated on the bank to offset each light.
Arm nulls: Children of offsets, there will be one arm null for each light in the rig. Arm nulls extend from the root of the rig via Y, and put the camera at an angle via Pitch. The arm nulls are static on an SLA, but on SSF and SSH rigs each arm is given 3 keyframes on the Y. This change in arm length during each exposure creates a spiral pattern, filling in the hole created by basic SLA rigs. If you are using 3 or more lights in a rig, I recommend the SSF rig type.
Lights: Children of each Arm, the lights themselves are static and keyframed at zero for all motion channels.
Thus if we have a light called "rhino" that we spin into a 2 light SLA, we get the following hierarchy:
SLA_rhino_pointer
/ SLA_rhino_spinner /
SLA_rhino_offset_a
/ SLA_rhino_arm_a / SLA_light_a
SLA_rhino_offset_b
/ SLA_rhino_arm_b / SLA_light_b
Make SLA Rig parameters and options
Select Light to Rig: if you don't understand this option then step slowly away from your computer and never return.
Spin rig for a motion blur length of: set the desired motion blur length. In general this is 50% as our eyes are used to seeing motion blurs of 50% in film and video (see Important Notes for motion blur limits).
AA level: Low, Medium, High, or Extreme, relevant to basic SLA rig setup but not to SSH or SSF rig setup.
Blur Type: Normal or Dithered, relevant to basic SLA rig setup but not to SSH or SSF rigs.
Adjust AA levels and blur lengths on cameras: This option will change the AA levels and blur lengths and types on all cameras in the scene to correspond with the options entered in this panel.
Number of Lights: 1-26
Light Angle: The angle that each light will be rotated. Positive will angle a light in towards the pointer, giving the rig a narrower beam, negative will do the opposite.
Arm Length: In meters, sets the length of each arm. This is the most important factor in determining how soft your shadows will be. Longer arms produce softer shadows but require higher antialiasing to look good.
Z Slip: In meters, how far will the rig move forward during each exposure. If z-slip is on, the spinner's Z will have 3 keyframes that cause the light to move forward during each exposure.
Make Spinning:
If you choose this option, a SSF or SSH will be created rather than an SLA
(see the Anatomy of an SLA above for an explanation).
Arm Change: A percentage value setting how much the arm length will change
during each exposure. A value of 100% will cause the arms to go from zero to
full arm length, while a value of 50% will cause the arm to go from half to
full arm length during each exposure. Values of 100% are not recommended as
this will lead to overlapping samples.
Spiral Spin: This option determines how much the spiral will spin. See
Tips on Understanding the
Different Rig Types below.
Make SLM Rig (Spinning Light Manual)
This option creates an SLM (Spinning Light Manual) with up to four lights. In some ways this option is more flexible than SLAs, as each light can have a different arm length and angle as well as non-uniform offsets. I call it "Manual" because the user needs to input values for the offset, length, and angle for each arm in the rig.
The hierarchy of an SLM is identical to that of SLAs. Like basic SLAs, SLMs spin according to the number of Motion Blur Samples (which is determined by AA level and blur type), but unlike SLAs, SLMs spin the same amount no matter how many lights are in the rig.
Make SLM Rig parameters and options
If you understand the options for making SLAs, all the available options for making SLMs should be obvious, with the exception of one.
Optimize offsets for AA level: this gives you the option to override the entered offset values and have Super Spinner assign offset values designed to provide the smoothest shadows. The offsets Super Spinner provides are a function of AA level, blur type, and the number of lights in the rig.
Make LAR Rig (Light Array)
This option produces a light array of up to 26x26 lights. The LAR rig hierarchy is:
pointer / slipper (for x,y, & z slip) / offset (one for each row) / arm (one for each light) / light
LARs have a double alpha postfix. The first letter is the row, the second is the column. The rigs are built such that the original light (light_aa) is set in the center of the rig (slightly off center if your rig has even numbers of rows or columns). Columns and rows grow out from the center. Thus if you read down a row or column it will not read "abcde", instead it will read "ecabd". I did it this way because it is nice to have the whole rig centered around the original location of the light.
motion blur: only relevant if you enter slip values.
Number of Rows: no duh.
Number of Columns: double no duh.
X separation: distance in meters between each light in a row.
Y separation: distance in meters between each light in a column.
Row Offset: This causes every other row to be staggered. An offset of 50% will offset rows by half of the X separation value.
X slip: Percent of the X separation value the whole rig will slip to the side during each exposure.
Y slip: Percent of the Y separation value the whole rig will slip up during each exposure.
ZigZag: If this option is activated, during each exposure the rig will slip up AND down by the Y slip percentage, rather than just up. This option may yield better results if you are using both X and Y slip.
Z slip: amount the whole rig will slip on the Z axis during each exposure, in meters.
unSpin Rig
This option will clear the selected rig and replace it with the original light (light_a). Light_a will be given its old name and the motion, children, and parents of the rig pointer. The intensity value (or envelope) will be compensated if the rig contained more than one light. There is an option to unSpin all rigs. If you activate this option, Super Spinner will unSpin every rig of every type. Note that if you have altered a rig's names or hierarchy, Super Spinner may not be able to identify a rig or perform unSpin properly.
Please note that due to limitations in the way LScript can interact with Layout, when you unSpin you will be presented with 2 familiar dialogue boxes (Clear Item and Clear Descendants). If you are unSpinning one rig, press YES on both. If you are unSpinning multiple rigs, press YES TO ALL on both.*
* I have noticed a bug in Layout that sometimes causes an extra object to be queued for deletion in Layout. If you press YES TO ALL, you risk this happening. If you want to be careful, don't press YES TO ALL and instead press YES twice for each Pointer you are presented with.
reSpin Rig
This option is only available for SLAs and SLA subtypes (SSH and SSF). It is simply a shortcut for unSpinning a rig and then spinning it again. If you alter the values of light_a you can use this feature to quickly clone the new values over to the other lights in the rig. If you have altered values of rig components other than light_a or the Pointer, reSpinning is not recommended.
Once you select a light to reSpin and press OK, you will be presented with the same Clear Object dialogue boxes that appear when unSpinning a rig. That is because you are unSpinning a rig. Press YES twice and you'll be presented with a window to input new rig values. The values of the unSpun rig should be presented as defaults. If you press Cancel at this point, your light will remain unSpun.
Optimize Scene
This option allows you to change some values globally, and is very useful if you have changed FPS (which, among other nasty side-effects, will cause spinner keyframes to shift out of place).
FPS: Enter your target frames per second. Default is the scene's current FPS.
Antialiasing: Enter your target antialiasing level.
Blur Type: Normal or Dithered.
Blur Length: Enter your target blur length. Default is the first camera's blur length.
Adjust all Cameras & Rigs: This will change the scene's FPS while keeping all the spinner null keyframes between -1 and 0. It will properly position bank and z-slip keyframes (as well as x and y-slip keyframes on LARs) according to blur length. Finally, it will properly position arm keyframes of SSH and SSF arm Y channels according to blur length. If you don't understand why this is necessary, do a quick test. Keyframe an item. Change the scene's FPS. See how the keyframes shift. Layout does this to keep your animation properly timed, regardless of frame rate. Well, this throws spinning light keyframes off, as the keyframes no longer match the period when the camera's virtual shutter is open and they no longer repeat over exactly 1 frame. That is what this button takes care of...
Optimize SLM offsets for AA level: What, you're a weirdo using SLMs? More power to you. This will adjust the bank rotations of each offset null in every SLM rig based on the chosen AA level. This should result in smoother shadows.
Information
A brief description of each function can be found here.
Copyright Dug Stanat 2001, all rights reserved.
Documentation can
be found at www.dugosaurus.com
Please send comments, questions, suggestions, insights, and above all bug reports
to dug@dugosaurus.com.
I take no responsibility for any harm this LScript may cause you. Enjoy!
Exit
Selecting this option and pressing OK will quit Super Spinner.
Important Notes
1) When you spin a light, it gets a postfix of "light_a". The intensity value (or envelope) of light_a will be divided by the number of lights in the rig. All other lights in the rig are clones of light_a. The root of the rig, (given the postfix "_pointer") will inherit the original light's parent, children, and motion. It will not inherit motion modifiers. When you unSpin, light_a is returned to its former lonely state. It's intensity is readjusted up if there were multiple lights in the rig and it reclaims the _pointer's parent, children, and motion.
2) When a rig is created, Channels that you most likely won't want to alter will be deactivated. Channels that you may want to adjust include all position and rotation channels of Pointers (controls motion of rig). Arm Pitch and Y position (controls light angles and arm lengths). For SLMs, Offset banks can also be adjusted (controls offset of each arm). It is not recommended to adjust Offset banks on SLAs because all offsets should be equal and are determined by the number of lights in the rig. All keyframes created by Super Spinner will be between Frame -1 and Frame 0.
3) It is highly recommended that you do not alter the names or hierarchies of SLA and SLM rigs. Super Spinner relies on a specific naming and hierarchy scheme, so if you alter your rigs, you are likely not to be able to unSpin them.
4) Turn off Parent-In-Place before running Super Spinner!
5) Super Spinner restricts Motion Blur Length to values between 2.5% and 99.17%. The lower limit is imposed because Layout cannot smoothly change values over a very short period of time. 2.5% is enough time for a rig to rotate smoothly at Low antialiasing. The higher the number of samples, the more time Layout needs, so if you are using High antialiasing, your blur length should not be less than 10%. The upper limit is imposed because Super Spinner uses 3 keyframes instead of two to govern the repetitive rig movements, and this is not possible with a motion blur of 100% (and any greater motion blur would prevent the repetition from being consistent over every frame).
Tips on Understanding the Different Rig Types
To be able to see what your spinning rigs are actually doing, go into the Layout options panel (o) and turn on Allow Fractional Current Frame. Then set your In and Out frames to -1 and 0. Now you can scrub and easily see exactly what the rig is doing over the course of each frame. Create a rig of each type and compare their behavior. If you want to see exactly what pattern a rig is making, give the lights a very small angle with no falloff, point the rig directly at a wall, and render. This should give you a pattern of dots that is much easier to read than a bunch of shadows.
Figure 4:
Spinning Rig Patterns (colors identify individual lights)
a: 3 light SLA, low AA
b: 3 light SSH, 80% Arm Change, low AA
c: 3 light SSF, 80% Arm Change, low AA
d: 3 light SLM, low AA
e: 6 light SSF, low AA
Figure 5:
Array Patterns (colors identify rows of 3 lights)
a: 3x3 LAR
b: 3x3 LAR, 50% offset
c: 3x3 LAR, 80% X-slip, low AA
d: 3x3 LAR, 80% X-slip, 80% Y-slip, low AA
e: 3x3 LAR, 80% X-slip, 80% Y-slip, zigzag On, low AA
Tips on Rig Adjustment
You can interactively adjust arm length in Layout by using the size tool (shift-H) on the pointer null (don't use the stretch tool unless you want to create an ellipse).
You can create a Favorites Set for all the arm nulls in a rig so you can quickly select and modify both the arm length and angle of all the arms at once.
Do you wish you could adjust the intensity of all the lights in a rig at once? Well, you can just unSpin, adjust the light, and then spin the light again. But there is also a way to adjust light intensity interactively without having to unSpin Before you rig a light, assign a null or master channel as a controller for the light's intensity (using ChannelFollower or expressions). Then, since Super Spinner clones your original light, all the lights in the rig will be controlled by the null. If you do this, you will have to manually adjust the controlling channel to compensate for the increased light caused by multiple lights (this is normally done automatically by Super Spinner)
But hey, why not take it a step further? You can control all the envelopes of all lights in a rig this way (intensity, RGB, intensity falloff, cone angle and edge, and more, including volumetric light option envelopes). A very cool way to set this up is to use a controller light. Before spinning your light_a, create another controller light. Assign all of light_a's envelopes to be controlled by the corresponding envelopes of the controller light. Turn off the controller light's options to affect diffuse and specular so the controller light has no direct effect on your renders. Now spin your light into multi-light rig. Wow! now your can use the envelopes on your one controller light to control every light in the rig. Pretty cool. What? you didn't have the foresight to set this up before spinning your rig? Just unSpin your rig, assign the controllers, and reSpin the rig. Super Spinner makes it easy!
If you are using Super Spinner with area or linear lights and you size the lights before spinning them, the pointer null will adopt the size and the lights will lose the size. Bummer. An easy way to get around this is to assign a controller (as explained above) to the light to control its size.
Tips on Makin' Purty Shadows
I like to use smaller angles and longer arms. What is a good arm length depends on how far from your target the light is. I usually turn off raytracing and use shadow maps with a shadow fuzziness greater than the default 1 but less than 8. You can quickly set up multiple rigs with very large arms spinning around your entire scene to get nice ambient light.
Try parenting a null to a spotlight and targeting the light to the null. Now spin the light. The target is now parented to the Pointer. Move the target, and all the lights track it. Try rendering with the target in different positions. Notice that the shapes of shadows do not change, only where the light is cast and focused. This is an interesting lesson: the angle of a spot light or point light will not affect the shape of a shadow, while the angle of a distant, area, or linear light will.
Distant light shadows are unique because a light's position will not change the shadow...only rotation. So how do you use the Spinning Light Trick with Distant lights? You can use targeting techniques to change the rotations of Distant lights (an interesting example is shown at menithings.com). I prefer to just assign an angle value when setting up the rig in Super Spinner. That will give each distant light a different pitch and thus a different shadow. In the case of distant lights, arm length is irrelevant unless a targeting technique is being used (but an arm length can make it easier to visually see what is going on).
As stated before, Light Arrays can produce excellent results while maintaining reasonable render times. Being able to keyframe between discrete frames gives you the ability to have a single array cast shadows from any angle during each motion blur sample. This is the case in Figure 6c, where a 25 light rig moves up and over the objects, casting 125 different shadows during each frame.
Figure
6: Area Light vs. Shadow Mapped Arrays
a: single area light, no AA, 4 seconds
b: 25 light LAR, no AA, 5 seconds
c: 25 light LAR, low AA, moved up and over objects during exposure, 23 seconds.
Figure 7 shows a progression from single light to a 6 light SSF. In 7a we see a single shadow mapped light. 7b shows the light turned into an SLA with a short arm. The shadow is softer but doesn't fade very much with distance, so the arm length was increased as seen in 7c. 7c is pretty nasty because the arm length is so long the SLA shadow develops a hole. To combat the hole, the SLA is converted into a SSH in 7d. This fills the hole. A similar if slightly better result is seen with a SSF in 7e. Finally, in 7f we see the rig respun into a 6 light SSF with an even longer arm and at medium AA the result is a very convincing soft shadow.
Figure 7:
Spinning Light Shadows
a: single shadow mapped light
b: 3 light SLA, low AA, short arm
c: 3 light SLA, low AA, medium arm
d: 3 light SSH, low AA, medium arm
e: 3 light SSF, low AA, medium arm, 4 sec
f: 6 light SSF, medium AA, long arm, 11 sec
Increasing Shadow Fuzziness is an effective way to blend your shadows together. In Figure 8a we can clearly see different shadows being cast from the column. Probably not what we want. One can either increase the number of lights or AA level, thus increasing render times, or increase Shadow Fuzziness. While Fuzzy maps are a time saver, they are also problematic when objects actually touch the ground. The fuzziness causes light areas where the eye desperately wants to see darkness. In Figure 8b we can see the right corner of the cube is a real problem area. Furthermore, the sphere is starting to look like it is floating off the ground.
Figure
8: Fuzzy vs. Sharp Shadow Maps
a: Relatively sharp shadow map with nasty banded shadow
b: Relatively soft shadow map with nasty "where is the shadow" effect
where objects touch the ground
Above all, experiment. If you find an innovative way to use Super Spinner, let me know! If there is another type of rig you'd like to see included in Super Spinner, let me know!
FAQ
1) What is a spinning light? It is a light that get spun very fast by a null in order to create soft shadows. For spinning lights to work motion blur must be on.
2) Where can I get more information on spinning lights. Search out Dave Jerrard's excellent tutorial on spinning lights. It was at one time included on the CD for the LightWave 3D Applied book.
3) Why did my scene get darker? If a light is affecting OpenGL and you spin it into a multi-light rig, layout will appear darker because the intensity of the original light is decreased. Your rendered scene should not appear darker.
4) How can I use spinning lights but not have my objects blur with motion blur? Go to Optimize Scene and make blur length really small, like 2.5%. Your rigs will spin really fast, and your objects will only be motion blurred 2.5% in each frame. Note that it seems to me that LightWave does not calculate the tweens properly if blur length is too short, so Super Spinner has a minimum blur length of 2.5%. The more motion blur samples the camera takes, the higher the minimum acceptable blur length is (10% works fine for high AA).
5) How can I create a spinning light with more than 26 lights? Parent one rig to another and bank the child rig's pointer null an appropriate amount so each rig doesn't cast the same shadows.
6) What versions of LightWave will Super Spinner work on. Super Spinner was written for LScript 2.1.1 and thus will work on LightWave 6.5. A new version, Beta 03, is available for LightWave 6.5b and LScript 2.2.