From 5d82c3cdb9f19ca1e081903572b51b91895da1f8 Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Mon, 10 Apr 2017 13:59:16 +0200
Subject: [PATCH] rename ComposeDst* -> ComposeR* + add ComposePlus,
 ComposeCopy

---
 interface.go      | 10 ++++++----
 pixelgl/canvas.go | 12 ++++++++----
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/interface.go b/interface.go
index fed7ac8..d92d460 100644
--- a/interface.go
+++ b/interface.go
@@ -56,11 +56,13 @@ const (
 	ComposeIn
 	ComposeOut
 	ComposeAtop
-	ComposeDstOver
-	ComposeDstIn
-	ComposeDstOut
-	ComposeDstAtop
+	ComposeRover
+	ComposeRin
+	ComposeRout
+	ComposeRatop
 	ComposeXor
+	ComposePlus
+	ComposeCopy
 )
 
 // Triangles represents a list of vertices, where each three vertices form a triangle. (First,
diff --git a/pixelgl/canvas.go b/pixelgl/canvas.go
index 5ebe5bf..df71f6d 100644
--- a/pixelgl/canvas.go
+++ b/pixelgl/canvas.go
@@ -153,16 +153,20 @@ func setBlendFunc(cmp pixel.ComposeMethod) {
 		glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.Zero)
 	case pixel.ComposeAtop:
 		glhf.BlendFunc(glhf.DstAlpha, glhf.OneMinusSrcAlpha)
-	case pixel.ComposeDstOver:
+	case pixel.ComposeRover:
 		glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.One)
-	case pixel.ComposeDstIn:
+	case pixel.ComposeRin:
 		glhf.BlendFunc(glhf.Zero, glhf.SrcAlpha)
-	case pixel.ComposeDstOut:
+	case pixel.ComposeRout:
 		glhf.BlendFunc(glhf.Zero, glhf.OneMinusSrcAlpha)
-	case pixel.ComposeDstAtop:
+	case pixel.ComposeRatop:
 		glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.SrcAlpha)
 	case pixel.ComposeXor:
 		glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.OneMinusSrcAlpha)
+	case pixel.ComposePlus:
+		glhf.BlendFunc(glhf.One, glhf.One)
+	case pixel.ComposeCopy:
+		glhf.BlendFunc(glhf.One, glhf.Zero)
 	default:
 		panic(errors.New("Canvas: invalid compose method"))
 	}