From 818bda4882e5dd4a913e17d6d2ee415f5271e80b Mon Sep 17 00:00:00 2001
From: bloeys <bloeys@outlook.com>
Date: Thu, 4 Nov 2021 22:49:20 +0400
Subject: [PATCH] Vec2&Mat2 add/sub functions+mat size enum

---
 gglm/mat.go  | 11 ++++++++++-
 gglm/mat2.go | 40 ++++++++++++++++++++++++++++++++++++++--
 gglm/vec2.go | 10 ++++++++++
 3 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/gglm/mat.go b/gglm/mat.go
index d559117..ac0d8a2 100755
--- a/gglm/mat.go
+++ b/gglm/mat.go
@@ -1,7 +1,16 @@
 package gglm
 
+type MatSize int
+
+const (
+	MatSizeUnknown MatSize = iota
+	MatSize2x2
+	MatSize3x3
+	MatSize4x4
+)
+
 type Mat interface {
 	At(row, col int) float32
 	Set(row, col int, val float32)
-	Size() int
+	Size() MatSize
 }
diff --git a/gglm/mat2.go b/gglm/mat2.go
index 0a2a73a..193e99c 100755
--- a/gglm/mat2.go
+++ b/gglm/mat2.go
@@ -21,14 +21,30 @@ func (m *Mat2) Set(row, col int, val float32) {
 	m.Data[row*2+col] = val
 }
 
-func (m *Mat2) Size() int {
-	return 2
+func (m *Mat2) Size() MatSize {
+	return MatSize2x2
 }
 
 func (m *Mat2) String() string {
 	return fmt.Sprintf("| %f %f |\n| %f %f |", m.Data[0], m.Data[1], m.Data[2], m.Data[3])
 }
 
+//Add m += m2
+func (m *Mat2) Add(m2 *Mat2) {
+	m.Data[0] += m2.Data[0]
+	m.Data[1] += m2.Data[1]
+	m.Data[2] += m2.Data[2]
+	m.Data[3] += m2.Data[3]
+}
+
+//Add m -= m2
+func (m *Mat2) Sub(m2 *Mat2) {
+	m.Data[0] -= m2.Data[0]
+	m.Data[1] -= m2.Data[1]
+	m.Data[2] -= m2.Data[2]
+	m.Data[3] -= m2.Data[3]
+}
+
 //Scale m *= x (element wise multiplication)
 func (m *Mat2) Scale(x float32) {
 	m.Data[0] *= x
@@ -37,6 +53,26 @@ func (m *Mat2) Scale(x float32) {
 	m.Data[3] *= x
 }
 
+//AddMat2 m3 = m1 + m2
+func AddMat2(m1, m2 *Mat2) *Mat2 {
+	return NewMat2([]float32{
+		m1.Data[0] + m2.Data[0],
+		m1.Data[1] + m2.Data[1],
+		m1.Data[2] + m2.Data[2],
+		m1.Data[3] + m2.Data[3],
+	})
+}
+
+//SubMat2 m3 = m1 - m2
+func SubMat2(m1, m2 *Mat2) *Mat2 {
+	return NewMat2([]float32{
+		m1.Data[0] - m2.Data[0],
+		m1.Data[1] - m2.Data[1],
+		m1.Data[2] - m2.Data[2],
+		m1.Data[3] - m2.Data[3],
+	})
+}
+
 //NewMat2 returns the identity matrix if data=nil, otherwise data is used
 //as the backing array.
 //
diff --git a/gglm/vec2.go b/gglm/vec2.go
index a25852e..195acbb 100755
--- a/gglm/vec2.go
+++ b/gglm/vec2.go
@@ -60,6 +60,16 @@ func (v *Vec2) SqrMag() float32 {
 	return v.X()*v.X() + v.Y()*v.Y()
 }
 
+//AddVec2 v3 = v1 + v2
+func AddVec2(v1 *Vec2, v2 *Vec2) *Vec2 {
+	return NewVec2([]float32{v1.X() + v2.X(), v1.Y() + v2.Y()})
+}
+
+//SubVec2 v3 = v1 + v2
+func SubVec2(v1, v2 *Vec2) *Vec2 {
+	return NewVec2([]float32{v1.X() - v2.X(), v1.Y() - v2.Y()})
+}
+
 func NewVec2(data []float32) *Vec2 {
 
 	if data == nil {