Cache TOP

From TouchDesigner 088 Wiki

CacheTOP 15.jpg

Summary

The Cache TOP stores a sequence of images into GPU memory. These cached images can be read by the graphics card much faster than an image cache in main memory or reading images off disk.

The Cache TOP can be used to freeze images in the TOP by turning the On parameter to 0. (You can set the cache size too 1.)

The Cache TOP acts as a delay if you set Output Index to negative numbers and leaving the On parameter at 1.

Once a sequence of images has been captures by turning the On parameter on and off, they can be looped by animating the Output Index parameter.

PythonIcon.png cacheTOP_Class

Parameters - Cache Page

Active active activepulse - While this is set > 0, the Cache TOP will capture images into its memory.

Get One Image On Startup cacheonce - Checking this On will cook the TOP once after startup to load an initial image.

Replace Single replacesingle replacesinglepulse - While this is set > 0, the Cache TOP will replace the image at 'Replace Index' with the input image. This allows you to replace specific images in the cache at will.

Replace Index replaceindex - Select the image index that will be replaced by the input, when 'Replace Single' is turned on.

Pre-Fill prefill - Cooks 'Cache Size' number of times to fill the Cache TOP with images. When set to 1, it will fill the cache. If set to 1 during playback, it will fill immediately. If set to 1 and saved out, then next time the file is opened the cache will pre-fill. While this is > 0, the node behaves as if the 'On' parameter is 0. If set to 0, then back > 0, it will clear the previous data, and pre-fill again. For more information refer to the Pre-Filling article.

Cache Size cachesize - Determines the number of images that can be stored in this Cache TOP.

Step Size step - The number of cooks that go by before the Cache TOP grabs an image. A Step Size of 2 will cache an image every 2nd cook, a Step Size of 3 will cache every 3rd cook, and so on.

Output Index outputframe - Determines which image in cache the TOP outputs. 0 is the most recent image, negative integers output image further back in time.

Output Index Units menu outputframeunit - Sets the units used in the Output Index parameter.

  • I - Index - units are samples.
  • F - Frames - units are in frames.
  • S - Seconds - units are in seconds. To access the image 2.0 seconds back in time, enter -2.0.
  • % - Fraction - units are a fraction of 1. -1.0 is the oldest image, -0.5 is halfway through the cache, and 0 is the most recent image.

Interpolate Between Frames interp - When On (On = 1), the Cache TOP will interpolate between frames when non-integer values are used in the Output Index parameter. For example, a value of -0.5 in Output Index will output a blended image of the most recent frame (0.0) and the second most recent frame (-1.0).

Always Cook alwayscook - Forces the operator to cook every frame.

Reset reset resetpulse - This will empty the cache of stored images and release the memory held by the TOP.

Parameters - Common Page

Resolution - quickly change the resolution of the TOP's data.

  • Input - uses the input's resolution.
  • Eighth, Quarter, Half, 2X, 4X, 8X - multiply the input's resolution by that amount.
  • Fit Resolution - Resizes the input to the size specified in Resolution using the best possible match that does not crop any of the input. It will resize the image to be larger than the input resolution if a larger resolution is specified. It's a "fit inside", Aspect Ratio is maintained.
  • Limit Resolution - Limits the input to the size specified in Resolution using the best possible match that does not crop any of the input. It's a "fit inside", Aspect Ratio is maintained.
  • Custom Resolution - enables the Resolution parameter below, giving direct control over width and height.

Resolution - enabled only when the Resolution parameter is set to Custom Resolution. Some Generators like Constant and Ramp do not use inputs and only use this field to determine their size. The drop down menu on the right provides some commonly used resolutions.

Use Global Resolution Multiplier - Uses the Global Resolution Multiplier found in Edit>Preferences>TOPs. This multiplies all the TOPs resolutions by the set amount. This is handy when working on computers with different hardware specifications. If a project is designed on a desktop workstation with lots of graphics memory, a user on a laptop with only 64MB VRAM can set the Global Resolution Multiplier to a value of half or quarter so it runs at an acceptable speed. By checking this checkbox on, this TOP is affected by the global multiplier.

Output Aspect - sets the image aspect ratio allowing any textures to be viewed in any size. Watch for unexpected results when compositing TOPs with different aspect ratios. (You can define images with non-square pixels using xres, yres, aspectx, aspecty where xres/yres != aspectx/aspecty.)

  • Input - uses the input's aspect ratio.
  • Resolution - uses the aspect of the image's defined resolution (ie 512x256 would be 2:1), whereby each pixel is square.
  • Custom Aspect - lets you explicitly define a custom aspect ratio.

Input Smoothness - This controls pixel filtering on the input image of the TOP.

  • Nearest Pixel - uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels - uses linear filtering between pixels. This is how you get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels - uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.

Fill Viewer - determine how the TOP image is displayed in the viewer.

  • Input - uses the same Fill Viewer settings as it's input.
  • Fill - stretches the image to fit the edges of the viewer.
  • Fit Horizontal - stretches image to fit viewer horizontally.
  • Fit Vertical - stretches image to fit viewer vertically.
  • Fit Best - stretches or squashes image so no part of image is cropped.
  • Fit Outside - stretches or squashes image so image fills viewer while constraining it's proportions. This often leads to part of image getting cropped by viewer.
  • Native Resolution - displays the native resolution of the image in the viewer.

NOTE: To get an understanding of how TOPs works with images, you will want to set this to Native Resolution as you lay down TOPs when starting out. This will let you see what is actually happening without any automatic viewer resizing.

Viewer Smoothness - This controls pixel filtering in the viewers.

  • Nearest Pixel - uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels - uses linear filtering between pixels. Use this to get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels - uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail. When the input is 32-bit float format, only nearest filtering will be used (regardless of what is selected).

Passes - duplicates the operation of the TOP the specified number of times.

Channel Mask - Allows you to choose which channels (R, G, B, or A) the TOP will operate on. All channels are selected by default.

Pixel Format - format used to store data for each channel in the image (ie. R, G, B, and A). Fixed format values are limited to the range [0-1]. Refer to Pixel Formats for more information.

  • Input - uses the input's pixel format.
  • 8-bit fixed (RGBA) - uses 8-bit integer values for each channel.
  • 16-bit float (RGBA) - uses 16-bits per color channel, 64-bits per pixel.
  • 32-bit float (RGBA) - uses 32-bits per color channel, 128-bits per pixels.


  • 10-bit RGB, 2-bit Alpha, fixed (RGBA) - uses 10-bits per color channel and 2-bits for alpha, 32-bits total per pixel.
  • 16-bit fixed (RGBA) - uses 16-bits per color channel, 64-bits total per pixel.
  • 11-bit float (RGB), Positive Values Only - A RGB floating point format that has 11 bits for the Red and Green channels, and 10-bits for the Blue Channel, 32-bits total per pixel (therefore the same memory usage as 8-bit RGBA). The Alpha channel in this format will always be 1. Values can go above one, but can't be negative. ie. the range is [0, infinite).
  • 8-bit fixed (R) - has 8-bits for the red channel, 8-bits total per pixel.
  • 16-bit fixed (R) - has 16-bits for the red channel, 16-bits total per pixel.
  • 16-bit float (R) - has 16-bits for the red channel, 16-bits per pixel.
  • 32-bit float (R) - has 32-bits for the red channel, 32-bits per pixel.
  • 8-bit fixed (RG) - has 8-bits for the red and green channels, 16-bits total per pixel.
  • 16-bit fixed (RG) - has 16-bits for the red and green channels, 32-bits total per pixel.
  • 16-bit float (RG) - has 16-bits for the red and green channels, 32-bits per pixel.
  • 32-bit float (RG) - has 32-bits for the red and green channels, 64-bits per pixel.
  • 8-bit fixed (A) - An Alpha only format that has 8-bits per channel, 8-bits per pixel.
  • 16-bit float (A) - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
  • 32-bit float (A) - An Alpha only format that has 32-bits per channel, 32-bits per pixel.