Transparency map - Revision history

EricChadwick: /* Blending Operations */ redirect

2020-05-20T14:40:54Z

‎Blending Operations: redirect

2020-05-20T14:17:35Z

‎Blending Operations: Blends | Unreal Engine Documentation

2020-05-20T02:01:41Z

‎Blending Operations

2020-05-20T01:51:51Z

‎Blending Operations: Insight into Photoshop 7.0 Blending Modes

2015-04-10T13:31:01Z

‎Why Does This Happen?: depth peeling

2015-03-14T14:36:06Z

‎Alpha Test: clearer

2015-03-14T14:34:16Z

‎Alpha Test

2015-03-14T14:33:11Z

‎Alpha Test: gallery size

2015-03-14T14:04:20Z

‎Alpha Blend: images: alpha blend vs alpha test

2015-03-02T03:57:42Z

SignedDistanceAlphaTest.png

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 == Blending Operations ==
-Usually the transparency map combines the surface's color (source) with the background color (destination) in a linear way like the "Normal" blending mode in Photoshop. The most common transparency blending methods in games are Normal (aka [[Lerp|Lerp]]), Additive, and Multiply, however there are many others available as well.
+See the page on [[MultiTexture#Blending_Operations|MultiTexture]]
-−
-* [https://docs.unrealengine.com/en-US/Engine/Rendering/Materials/Functions/Reference/Blends/index.html Blends | Unreal Engine Documentation] has blending functions that replicate common Photoshop methods.
-−
-* [https://polycount.com/discussion/180954/alpha-blend-source-destination-matrix Alpha Blend - Source/Destination matrix] has visual examples for commonly available shader blending modes.
-−
-* [https://dunnbypaul.net/blends/ Insight into Photoshop 7.0 Blending Modes] has the math behind many of them.
 ----
 [[Category:Texturing]] [[Category:TextureTypes]]

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 Usually the transparency map combines the surface's color (source) with the background color (destination) in a linear way like the "Normal" blending mode in Photoshop. The most common transparency blending methods in games are Normal (aka [[Lerp|Lerp]]), Additive, and Multiply, however there are many others available as well.
-* [https://dunnbypaul.net/blends/ Insight into Photoshop 7.0 Blending Modes] has the math behind many of them.
+* [https://docs.unrealengine.com/en-US/Engine/Rendering/Materials/Functions/Reference/Blends/index.html Blends | Unreal Engine Documentation] has blending functions that replicate common Photoshop methods.
 * [https://polycount.com/discussion/180954/alpha-blend-source-destination-matrix Alpha Blend - Source/Destination matrix] has visual examples for commonly available shader blending modes.
 ----
 [[Category:Texturing]] [[Category:TextureTypes]]

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 * [https://dunnbypaul.net/blends/ Insight into Photoshop 7.0 Blending Modes] has the math behind many of them.
 ----
 [[Category:Texturing]] [[Category:TextureTypes]]

@@ Line 139: / Line 139: @@
 Usually the transparency map combines the surface's color (source) with the background color (destination) in a linear way like the "Normal" blending mode in Photoshop. The most common transparency blending methods in games are Normal (aka [[Lerp|Lerp]]), Additive, and Multiply, however there are many others available as well.
-* [http://www.myinkblog.com/2009/07/14/an-explanation-of-photoshop-blend-modes/ An Explanation of Photoshop Blend Modes] - from an artist's perspective
+* [https://dunnbypaul.net/blends/ Insight into Photoshop 7.0 Blending Modes] has the math behind many of them.
-* [http://stackoverflow.com/questions/5919663/how-does-photoshop-blend-two-images-together How does photoshop blend two images together?] - from a coder's perspective
 ----
 [[Category:Texturing]] [[Category:TextureTypes]]

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 </gallery>
-The perfect solution for per-pixel soft transparency would be to sort the surfaces per-pixel, but there's no consumer-grade hardware that currently does this.
+Maya offers a Viewport 2.0 method called Depth Peeling which often improves transparency sorting in most situations. The viewport is rendered in 2 to 10 passes (adjustable in the settings) which are combined into each final frame. For details see the Nvidia whitepaper [https://developer.nvidia.com/content/interactive-order-independent-transparency "Interactive Order-Independent Transparency"]. However depth peeling is still too expensive to use in most 3d games.
 * [http://blogs.msdn.com/b/shawnhar/archive/2009/02/18/depth-sorting-alpha-blended-objects.aspx Depth sorting alpha blended objects] by Shawn Hargreaves is a great description of how alpha blending is rendered in a game engine.

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 There are no depth sorting problems with alpha test, but there's also no [[AntiAliasing|anti-aliasing]] so it can get very pixelly at a distance. Alpha test is much faster to render in real-time than [[#AlphaBlend|alpha blend]].
-You get better results if you use a smooth grayscale in your alpha. If you use an alpha that's only black and white but no grays, you tend to get large stairsteps when it is alpha tested. For example the [[DXT]]1 texture format has only two colors in the alpha (black and white), and it is half the file size of the smooth-alpha format DXT5, but the trade-off is blocky rendering.
+You get better results if you use a smooth grayscale in your alpha. If you use an alpha that's only black and white but no grays, you tend to get large stairsteps when it is alpha tested. The [[DXT]]1 texture format has only on vs. off for transparency... it is half the file size of DXT5 (smooth alpha), but the trade-off is blocky edges.
 <gallery mode="nolines" heights=390px widths=1199px>

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 <gallery mode="nolines" heights=390px widths=1199px>
-alphatest_8bit_vs_1bit.jpg|Alpha test with 8bit alpha vs. 1bit alpha. <br/>Image by [http://ericchadwick.com Eric Chadwick].
+alphatest_8bit_vs_1bit.jpg|Alpha test with 8bit alpha vs. 1bit alpha. Alpha tested models (left), alpha channels (right).<br/>Image by [http://ericchadwick.com Eric Chadwick].
 </gallery>

← Older revision		Revision as of 14:04, 14 March 2015
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	Unfortunately alpha blend often has [[#Sorting_Problems\|Sorting problems]].		Unfortunately alpha blend often has [[#Sorting_Problems\|Sorting problems]].
		+
		+	<gallery mode="nolines" heights=320px widths=320px>
		+	transp_alphablend_sorted.jpg\|Grass using alpha blend, with 2-pass depth sorting. <br/>Image by [http://ericchadwick.com Eric Chadwick].
		+	transp_alphatest.jpg\|Grass using alpha test. <br/>Image by [http://ericchadwick.com Eric Chadwick].
		+	</gallery>

	=== Alpha Test ===		=== Alpha Test ===

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 === Signed Distance Alpha Test ===
 ''Signed distance alpha test'' is also similar to [[#AlphaTest|alpha test]], except it allows the texture size to be extremely small and still get decent results. Valve Software has a paper from SIGGRAPH 2007, [http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf Improved Alpha-Tested Magnification for Vector Textures and Special Effects]. Gamedev.net has a [http://www.gamedev.net/community/forums/topic.asp?topic_id=490373&forum_id=12&gforum_id=0 thread with pictures], and a [http://www.gamedev.net/blog/288/entry-1694633-improved-alpha-magnification couple] [http://www.gamedev.net/blog/288/entry-1696705-improved-alpha-magnification-2 more] threads with a demo app (in the comments).
 === Hybrid Approaches ===