From b610760f1c66e072345ee615a29b65c4349109ec Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Thu, 12 Jan 2017 13:50:06 +0100
Subject: [PATCH] add doc on default vertex properties values

---
 interface.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/interface.go b/interface.go
index 6130b81..479c3af 100644
--- a/interface.go
+++ b/interface.go
@@ -60,12 +60,16 @@ type Drawer interface {
 }
 
 // TrianglesPosition specifies Triangles with Position property.
+//
+// Default value for a position is (0, 0).
 type TrianglesPosition interface {
 	Triangles
 	Position(i int) Vec
 }
 
 // TrianglesColor specifies Triangles with Color property.
+//
+// Default value for a color is the white color.
 type TrianglesColor interface {
 	Triangles
 	Color(i int) color.Color
@@ -74,6 +78,8 @@ type TrianglesColor interface {
 // TrianglesTexture specifies Triangles with Texture propery.
 //
 // Note that this represents texture coordinates, not an actual texture.
+//
+// Default value for a texture is (-1, -1), which means 'no texture'.
 type TrianglesTexture interface {
 	Triangles
 	Texture(i int) Vec