From 40b1948baa7b7fa5d05211d33ea970d4754f851a Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 20 Feb 2018 01:17:21 +0900
Subject: [PATCH] graphics: Stop unnecessary copy of elements

---
 internal/affine/colorm.go    | 2 +-
 internal/graphics/program.go | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/internal/affine/colorm.go b/internal/affine/colorm.go
index c81dcb128..079ccbb2f 100644
--- a/internal/affine/colorm.go
+++ b/internal/affine/colorm.go
@@ -44,7 +44,7 @@ var (
 // The initial value is identity.
 type ColorM struct {
 	// When elements is nil, this matrix is identity.
-	// elements is immutable and a new array must be created when updating.
+	// elements are immutable and a new array must be created when updating.
 	body      []float32
 	translate []float32
 }
diff --git a/internal/graphics/program.go b/internal/graphics/program.go
index 649127439..02317364a 100644
--- a/internal/graphics/program.go
+++ b/internal/graphics/program.go
@@ -271,14 +271,16 @@ func (s *openGLState) useProgram(proj []float32, texture opengl.Texture, sourceW
 		if s.lastColorMatrix == nil {
 			s.lastColorMatrix = make([]float32, 16)
 		}
-		copy(s.lastColorMatrix, esBody)
+		// ColorM's elements are immutable. It's OK to hold the reference without copying.
+		s.lastColorMatrix = esBody
 	}
 	if !areSameFloat32Array(s.lastColorMatrixTranslation, esTranslate) {
 		c.UniformFloats(program, "color_matrix_translation", esTranslate)
 		if s.lastColorMatrixTranslation == nil {
 			s.lastColorMatrixTranslation = make([]float32, 4)
 		}
-		copy(s.lastColorMatrixTranslation, esTranslate)
+		// ColorM's elements are immutable. It's OK to hold the reference without copying.
+		s.lastColorMatrixTranslation = esTranslate
 	}
 
 	if program == s.programLinear {