Render Pass TOP

From TouchDesigner 088 Wiki

Summary

The Render Pass TOP is used along with a Render TOP to achieve multipass rendering. It can build upon its inputs render by using the existing depth/color information in the framebuffers, or it can optionally clear one or both of the depth/color buffers before it does its render.

PythonIcon.png renderpassTOP_Class

Parameters - Render Pass Page

Render/Render Pass TOP /renderinput - The network path to the Render TOP used as input. This parameter can be used as an alternate to connecting a Render or Render Pass TOP to the Render Pass's input connector. Makes it easier to select a render from another network.

Camera /camera - Specifies which Camera to look through when rendering the scene.

Geometry /object - Specifies which Geometry will be included in the rendered scene.

Lights /lights - Specifies which Lights will be used to render the scene.

Clear to Camera Color /cleartocamcolor - Clears the values that are currently in the color buffer (coming from the TOP that is wired to the input of this node).

Clear Depth Buffer /cleardepth - Clears the values that are currently in the depth buffer (coming from the TOP that is wired to the input of this node).

Parameters - Advanced Page

Render /render - Enables rendering; 1 = on, 0 = off.

Draw Depth Only /drawdepthonly - This will cause the render to only draw depth values to the depth buffer. No color values will be created. To make use of the depth buffer, use the Depth TOP.

Color Output Needed /coloroutputneeded - This is an optimization if you don't actually need the color result from this pass. Turning this off avoids a copy from the offscreen render buffer to the TOP's texture. When anti-aliasing is enabled turning this off will also avoid 'resolving' the anti-aliasing.

Enable Anti-Aliasing /enableantialias - Enables or disables anti-aliasing for this TOP.

Enable Alpha-to-Coverage /alphatocoverage - This is a feature that allows you to control how the anti-alias is resolved by using the pixel's alpha value. Say the anti-alias setting is set to 4x. This means that for each final pixel color, it will blend the color values of 4 pixels from the anti-alias buffer. When Alpha-to-Coverage is enabled, the alpha value controls how many pixel samples will be used to create the final pixel value. If your alpha value is 0.75, then 3 of the 4 pixels will be used. If it's 0.5 then 2 of the 4 pixels will be used.

Enable Polygon Depth Offset /polygonoffset - This feature pushes the polygons back into space a tiny fraction. This is useful when you are rendering two polygons directly ontop of each other and are experiencing Z-Fighting. Refer to Polygon Depth Offset for more information. This is also an important feature when doing shadows.

Polygon Offset Factor /polygonoffsetfactor - Refer to to the same parameter in the Render TOPs help page.

Polygon Offset Units /polygonoffsetunits - Refer to to the same parameter in the Render TOPs help page.

Cull Face /cullface - Front Faces, Back Faces, Both Faces, Neither. Will cause the render to avoid rendering certain polygon faces depending on their orientation to the camera. Refer to Back-Face Culling for more information.

Override Material /overridemat - This allows you to specific a material that will be applied to every Geometry that is rendered in the Render TOP. It is useful for pre-processing passes where we are outputting infoformation about the geometry rather then lighting them and outputting RGB.

Order-Independent Transparency /orderindtrans - Refer to to the same parameter in the Render TOPs help page.

Transparency Passes /transpasses - Refer to to the same parameter in the Render TOPs help page.

Display Overdraw /overdraw - This feature visually shows the overdraw in the scene. Refer to the Early Depth-Test article for more information. In particular the Analyzing Overdraw section.

Overdraw Limit /overdrawlimit - This value quantizes the outputted color value to some # of overdraws. Refer to the Early Depth-Test for more information.

Parameters - GLSL Page

Refer to GLSL section on the Render TOPs help page.

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.