From 0e699be281c8dea53e589e08a5831837e0eae7ea Mon Sep 17 00:00:00 2001 From: David Thompson Date: Thu, 7 Oct 2021 20:17:50 -0400 Subject: Updates for Chickadee 0.8.0 and Guile-SDL2 0.7.0. --- manuals/chickadee/Blending.html | 204 ---------------------------------------- 1 file changed, 204 deletions(-) delete mode 100644 manuals/chickadee/Blending.html (limited to 'manuals/chickadee/Blending.html') diff --git a/manuals/chickadee/Blending.html b/manuals/chickadee/Blending.html deleted file mode 100644 index 0a54bbe..0000000 --- a/manuals/chickadee/Blending.html +++ /dev/null @@ -1,204 +0,0 @@ - - - - - - -Blending (The Chickadee Game Toolkit) - - - - - - - - - - - - - - - - - - - -
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2.3.10 Blending

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Rendering a scene often involves drawing layers of objects that -overlap each other. Blending determines how two overlapping pixels -are combined in the final image that is rendered to the screen. -

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Chickadee provides the following blend modes: -

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Variable: blend:alpha
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Blend pixels according to the values of their alpha channels. This is -the most commonly used blend mode. -

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Variable: blend:replace
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Overwrite the output pixel color with the color being drawn. -

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Variable: blend:add
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Add all pixel color values together. The more colors blended -together, the more white the final color becomes. -

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Variable: blend:subtract
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Subtract all pixel color values. The more colors blended together, -the more black the final color becomes. -

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Variable: blend:multiply
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Variable: blend:darken
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Variable: blend:lighten
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Variable: blend:screen
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Custom blend modes can be created using the make-blend-mode procedure: -

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Procedure: make-blend-mode equation source-function destination-function
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Return a new custom blend mode that applies source-function to -the source color, destination-function to the destination color, -and finally applies equation to the transformed -source/destination color values. These arguments are not -procedures, but symbolic representations of the functions that OpenGL -supports. -

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Valid values for equation are: -

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  • add -
  • subtract -
  • reverse-subtract -
  • min -
  • max -
  • alpha-min -
  • alpha-max -
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Valid values for source-function are: -

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  • zero -
  • one -
  • destination-color -
  • one-minus-destination-color -
  • source-alpha-saturate -
  • source-alpha -
  • one-minus-source-alpha -
  • destination-alpha -
  • one-minus-destination-alpha -
  • constant-color -
  • one-minus-constant-color -
  • constant-alpha -
  • one-minus-constant-alpha -
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Valid values for destination-function are: -

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  • zero -
  • one -
  • source-color -
  • one-minus-source-color -
  • source-alpha -
  • one-minus-source-alpha -
  • destination-alpha -
  • one-minus-destination-alpha -
  • constant-color -
  • one-minus-constant-color -
  • constant-alpha -
  • one-minus-constant-alpha -
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