Null MAT

Summary

The Null MAT has no effect on the data. It is an instance of the MAT connected to its input. It doesn't do much but comes in handy when building networks.

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Parameters - Common Page

Blending

Blending(Transparency) blending - This toggle 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).

• Zero zero -

• Dest Color dcol -

• One Minus Dest Color omdcol -

• Source Alpha sa -

• One Minus Source Alpha omsa -

• Dest Alpha da -

• One Minus Dest Alpha omda -

• Source Alpha Saturate sas -

• One one -

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).

• One one -

• Src Color scol -

• One Minus Src Color omscol -

• Source Alpha sa -

• One Minus Source Alpha omsa -

• Dest Alpha da -

• One Minus Dest Alpha omda -

• Zero zero -

Separate Alpha Function separatealphafunc - This toggle enables and disables separate blending options for the alpha values.  

Source Alpha * srcblenda - ⊞ - This value is multiplied by the alpha value of the pixel that is being written to the Color-Buffer (also know as the Source Alpha).

• Zero zero -

• Dest Color dcol -

• One Minus Dest Color omdcol -

• Source Alpha sa -

• One Minus Source Alpha omsa -

• Dest Alpha da -

• One Minus Dest Alpha omda -

• Source Alpha Saturate sas -

• One one -

Destination Alpha * destblenda - ⊞ - This value is multiplied by the alpha value of the pixel currently in the Color-Buffer (also known as the Destination Alpha).

• One one -

• Src Color scol -

• One Minus Src Color omscol -

• Source Alpha sa -

• One Minus Source Alpha omsa -

• Dest Alpha da -

• One Minus Dest Alpha omda -

• Zero zero -

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.

• Less Than less -

• Less Than or Equal lessorequal -

• Equal equal -

• Greater Than greater -

• Greater Than or Equal greaterorequal -

• Not Equal notequal -

• Always always -

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

• Less Than less -

• Less Than or Equal lessorequal -

• Greater Than greater -

• Greater Than or Equal greaterorequal -

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 with the option of OpenGL Tesselated or Topology based wireframes.

• Off off -

• OpenGL Tesselated Wire Frame tesselated -

• Topology Wire Frame topology -

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 userender - Use the render settings found in the Render or Render Pass TOP.

• Neither neither - Do not cull any faces, render everything.

• Back Faces backfaces - Cull back faces, render front faces.

• Front Faces frontfaces - Cull front faces, render back faces.

• Both Faces bothfaces - 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 -  

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