From 7f7912cc165748beae2ee6ee3b1d024cee3fa2bd Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Tue, 28 Feb 2017 18:24:31 +0100
Subject: [PATCH] minor changes

---
 batch.go     | 2 +-
 interface.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/batch.go b/batch.go
index 34fc0ea..c4b9c72 100644
--- a/batch.go
+++ b/batch.go
@@ -128,7 +128,7 @@ func (bp *batchPicture) Slice(r Rect) Picture {
 func (bp *batchPicture) Draw(t TargetTriangles) {
 	bt := t.(*batchTriangles)
 	if bp.b != bt.b {
-		panic(fmt.Sprintf("%T.Draw: TargetTriangles generated by different Batch", bp))
+		panic(fmt.Errorf("%T.Draw: TargetTriangles generated by different Batch", bp))
 	}
 	bt.draw(bp)
 }
diff --git a/interface.go b/interface.go
index 4530007..0894665 100644
--- a/interface.go
+++ b/interface.go
@@ -127,7 +127,7 @@ type TargetPicture interface {
 // PictureColor specifies Picture with Color property, so that every position inside the Picture's
 // Bounds has a color.
 //
-// Positions outside the Picture's Bounds must return opaque white (NRGBA{R: 1, G: 1, B:1, A: 1}).
+// Positions outside the Picture's Bounds must return transparent black (NRGBA{R: 0, G: 0, B: 0, A: 0}).
 type PictureColor interface {
 	Picture
 	Color(at Vec) NRGBA