Point Sprite MAT

From TouchDesigner 088 Wiki

Summary

The Point Sprite MAT allows you to control some attributes of Point Sprites (creatable using the Particle SOP or DAT to SOP). You can apply color, a color map, change the size of the created point sprite from a square to a rectangle, and scale the size of the point sprite.

A point sprite's final size controls the number of pixels wide/high it is, regardless of how far it is from the camera (unless you are using attenuation).

PythonIcon.png pointspriteMAT_Class

Parameters - Point Sprite Page

Color /color - The color of the light reflected from the material.

Alpha /alpha - The opacity of the material. This parameter is multiplied by point alpha of the object.

Post-Mult Color by Alpha /postmultalpha - Enable/disable multiplying color by alpha.

Color Map /colormap - The color map to apply to the sprites. The Color Map will be multiplied by the color of the sprites. The Color Map parameter can also take 3D / 2D Texture Arrays (from the Texture 3D TOP for example), and the w texture coordinate will select the correct map from the array.

The following 4 parameters control the width/height of the point sprites. For example setting Offset Left to 0.5 and Offset Right to 1.0 will cause the sprite to be half its full width, with the left edge of the sprite located at the 'middle' of its full width.

Offset Left /offsetleft -

Offset Right /offsetright -

Offset Bottom /offsetbottom -

Offset Top /offsetop -

The final size of the point sprite is controlled by the pscale point attribute (if present) getting multiplied of the result of the next 6 parameters. There are two types of scale this MAT can apply, and they are blended using the Attenuate Point Scale parameter to create one final point scale (which is multiplied by pscale).

Constant Point Scale /pointscale - A constant value that is applied to all points evenly. When Attenuate Point Scale is 0, the point sprite size will be pscale * this value.

Attenuate Point Scale /attenpscale - This value blends between the Constant Point Scale and the Attenuated Point Scale. 0 means 100% constant point scale and 1 means 100% attenuated point scale.

Points that are closer than or at the Near distance from the camera will use the Near Point Scale, points between the Near Distance and Far Distance will use a blended scale between the Near Point Scale and the Far Point Scale. Points farther than the Far Point Distance will use the Far Point Scale.

Attenuate Near Distance /attennear - Points that are closer than or at this distance from the camera will use the Near Point Scale Parameter.

Attenuate Far Distance /attenfar - Points that are farther than or at this distance from the camera will use the Far Point Scale Parameter.

Near Point Scale /attensizenear - This point scale is applied at the near distance.

Far Point Scale /attensizefar - This point scale is applied at the far distance.

Parameters - Deform Page

Refer to the Deform Article for more information on doing deforms in Touch.

Deform dodeform - Enables deforms on this material.

Get Bone Data: deformdata - Specifies where the deform bone data will be obtained.

SOP with capture data targetsop - Specifies the SOP that contains the deform capture attributes.

pCaptPath Attrib pcaptpath - Specifies the name of the pCaptPath attribute to use. When your geometry has been put through a Bone Group SOP, the attributes will be split into names like pCaptPath0, pCaptPath1. You can only render 1 bone group at a time, so this should match the group you are rendering with this material.

pCaptData Attrib pcaptdata - Much like pCaptPath Attrib.

Skeleton Root Path skelrootpath - Specifies the path to the COMP where the root of the skeleton is located.

MAT mat - When obtaining deform data from a MAT or a Deform In MAT, this is where that MAT is specified.

Parameters - Common Page

Blending

Blending is summing the color value of the pixel being drawn and the pixel currently present in the Color-Buffer. Blending is typically used to simulate Transparency.

The blending equation is:

Final Pixel Value = (Source Blend * Source Color) + (Dest Blend * Destination Color)

Blending (Transparency) blending - This checkbox enables and disables blending. However see the wiki article Transparency.

Source Color srcblend - This value is multiplied by the color value of the pixel that is being written to the Color-Buffer (also know as the Source Color).

Destination Color destblend - This value is multiplied by the color value of the pixel currently in the Color-Buffer (also known as the Destination Color).

Depth Test

Depth-Testing is comparing the depth value of the pixel being drawn with the pixel currently in the Frame-Buffer. A pixel that is determined to be in-front of the pixel currently in the Frame-Buffer will be drawn over it. Pixels that are determined to be behind the pixel currently in the Frame-Buffer will not be drawn. Depth-Testing allows geometry in a 3D scene to occlude geometry behind it, and be occluded by geometry in-front of it regardless of the order the geometry was drawn.

For a more detailed description of Depth-Testing, refer to the Depth-Test article.

Depth Test depthtest - Enables and disables the Depth-Test. If the depth-test is disabled, depths values aren't written to the Depth-Buffer.

Depth Test Function depthfunc - The depth value of the pixel being drawn is compared to the depth value currently in the depth-buffer using this function. If the test passes then the pixel is drawn to the Frame-Buffer. If the test fails the pixel is discarded and no changes are made to the Frame-Buffer.

Write Depth Values depthwriting - If Write Depth Values is on, pixels that pass the depth-test will write their depth value to the Depth-Buffer. If this isn't on then no changes will be made to the Depth-Buffer, regardless of if the pixels drawn pass or fail the depth-test.

Alpha Test

Alpha-testing allows you to choose to draw or not draw a pixel based on its alpha value.

Discard Pixels Based On Alpha alphatest - This enables or disables the pixel alpha test.

Keep Pixels with Alpha alphatest - This menu works in conjunction with the Alpha Threshold parameter below in determining which pixels to keep based on their alpha value.

Alpha Threshold alphathreshold - This value is what the pixel's alpha is compared to to determine if the pixel should be drawn. Pixels with alpha greater than the Alpha Threshold will be drawn. Pixels with alpha less than or equal to the Alpha Threshold will not be drawn.

Wire Frame

The wire-frame feature will render the geometry as wire-frame, using the actual primitive type used in the render. What this means is surfaces like Metaballs, NURBs and Beziers will become a wire-frame of the triangles/triangle-strips used to render them (since these types of primitives can't be natively rendered in OpenGL).

Wire Frame wireframe - Enables and disables wire-frame rendering.

Line Width wirewidth - This value is the width that the wires will be. This value is in pixels.

Cull Face

The cull face parameter will cull faces from the render output. This can be used as an optimization or sometimes to remove artifacts. See Back-Face Culling for more infomation.

Cull Face cullface - Selects which faces to render.

  • Use Render Setting - use the render settings found in the Render or Render Pass TOP.
  • Neither - do not cull any faces, render everything.
  • Back Faces - cull back faces, render front faces.
  • Front Faces - cull front faces, render back faces.
  • Both Faces - cull both faces, render nothing.

Polygon Depth Offset

This feature pushes the polygons back into space a tiny fraction. This is useful when you are rendering two polygons directly on-top 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 Depth Offset polygonoffset - Turns on the polygon offset feature.

Offset Factor polygonoffsetfactor -

Offset Units polygonoffsetunits -



Examples

This example shows a basic setup using the Point Sprite MAT.

Media:Point_Sprite_MAT_Basic.tox