From 5f8a0e34bbb46071f0c249c48fa8525788747cda Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 16 Dec 2018 14:22:47 +0900
Subject: [PATCH] graphics: isPowerOf2(0 or negative) should return false

---
 internal/graphics/vertices.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/internal/graphics/vertices.go b/internal/graphics/vertices.go
index a6276520b..5ef8af029 100644
--- a/internal/graphics/vertices.go
+++ b/internal/graphics/vertices.go
@@ -50,6 +50,9 @@ func (v *verticesBackend) slice(n int) []float32 {
 }
 
 func isPowerOf2(x int) bool {
+	if x <= 0 {
+		return false
+	}
 	return (x & (x - 1)) == 0
 }