From 87d4a5f27faffd2bdd74a444d39f967ab5aa0e8b Mon Sep 17 00:00:00 2001
From: Kenneth Russel <kbrussel@alum.mit.edu>
Date: Mon, 18 Feb 2008 08:58:39 +0000
Subject: Added table of Porter-Duff compositing rules in the face of
premultiplied alpha based on some code from the Java 2D OpenGL pipeline
git-svn-id: file:///usr/local/projects/SUN/JOGL/git-svn/svn-server-sync/jogl/trunk@1535 232f8b59-042b-4e1e-8c03-345bb8c30851
---
.../com/sun/opengl/util/texture/Texture.java | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
(limited to 'src/classes/com/sun')
diff --git a/src/classes/com/sun/opengl/util/texture/Texture.java b/src/classes/com/sun/opengl/util/texture/Texture.java
index d634f66fb..f4a0a8be2 100755
--- a/src/classes/com/sun/opengl/util/texture/Texture.java
+++ b/src/classes/com/sun/opengl/util/texture/Texture.java
@@ -111,6 +111,28 @@ import com.sun.opengl.util.texture.spi.*;
float b = b * a;
gl.glColor4f(r, g, b, a);
</pre>
+ *
+ * For reference, here is a list of the Porter-Duff compositing rules
+ * and the associated OpenGL blend functions (source and destination
+ * factors) to use in the face of premultiplied alpha:
+ *
+<CENTER>
+<TABLE WIDTH="75%">
+<TR> <TD> Rule <TD> Source <TD> Dest
+<TR> <TD> Clear <TD> GL_ZERO <TD> GL_ZERO
+<TR> <TD> Src <TD> GL_ONE <TD> GL_ZERO
+<TR> <TD> SrcOver <TD> GL_ONE <TD> GL_ONE_MINUS_SRC_ALPHA
+<TR> <TD> DstOver <TD> GL_ONE_MINUS_DST_ALPHA <TD> GL_ONE
+<TR> <TD> SrcIn <TD> GL_DST_ALPHA <TD> GL_ZERO
+<TR> <TD> DstIn <TD> GL_ZERO <TD> GL_SRC_ALPHA
+<TR> <TD> SrcOut <TD> GL_ONE_MINUS_DST_ALPHA <TD> GL_ZERO
+<TR> <TD> DstOut <TD> GL_ZERO <TD> GL_ONE_MINUS_SRC_ALPHA
+<TR> <TD> Dst <TD> GL_ZERO <TD> GL_ONE
+<TR> <TD> SrcAtop <TD> GL_DST_ALPHA <TD> GL_ONE_MINUS_SRC_ALPHA
+<TR> <TD> DstAtop <TD> GL_ONE_MINUS_DST_ALPHA <TD> GL_SRC_ALPHA
+<TR> <TD> AlphaXor <TD> GL_ONE_MINUS_DST_ALPHA <TD> GL_ONE_MINUS_SRC_ALPHA
+</TABLE>
+</CENTER>
*
* @author Chris Campbell
* @author Kenneth Russell
--
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