Make TrMat funcs chainable+more 32 scalar funcs

README.md

@@ -1,6 +1,6 @@
 # gglm
 
-Fast Go OpenGL Mathematics library inspired by the c++ library [glm](https://github.com/g-truc/glm).
+Fast Go OpenGL/Graphics focused Mathematics library inspired by the c++ library [glm](https://github.com/g-truc/glm).
 
 ## Notes
 

gglm/constants.go

@@ -1,7 +1,11 @@
 package gglm
 
 const (
-	Pi      float32 = 3.14159265359
-	Deg2Rad float32 = Pi / 180
-	Rad2Deg float32 = 180 / Pi
+	Pi         float32 = 3.14159265359
+	Deg2Rad    float32 = Pi / 180
+	Rad2Deg    float32 = 180 / Pi
+	F32Epsilon float32 = 1e-6
+
+	//CosHalf is Cos32(0.5)
+	CosHalf float32 = 0.87758256189
 )

gglm/mat2.go

@@ -28,6 +28,10 @@ func (m *Mat2) String() string {
 	return fmt.Sprintf("\n| %+-9.3f %+-9.3f |\n| %+-9.3f %+-9.3f |\n", m.Data[0][0], m.Data[0][1], m.Data[1][0], m.Data[1][1])
 }
 
+func (m *Mat2) Col(c int) *Vec2 {
+	return &Vec2{Data: m.Data[c]}
+}
+
 //Add m += m2
 func (m *Mat2) Add(m2 *Mat2) *Mat2 {
 	m.Data[0][0] += m2.Data[0][0]

gglm/mat3.go

@@ -31,6 +31,10 @@ func (m *Mat3) String() string {
 	)
 }
 
+func (m *Mat3) Col(c int) *Vec3 {
+	return &Vec3{Data: m.Data[c]}
+}
+
 //Add m += m2
 func (m *Mat3) Add(m2 *Mat3) *Mat3 {
 

gglm/mat4.go

@@ -32,6 +32,10 @@ func (m *Mat4) String() string {
 	)
 }
 
+func (m *Mat4) Col(c int) *Vec4 {
+	return &Vec4{Data: m.Data[c]}
+}
+
 //Add m += m2
 func (m *Mat4) Add(m2 *Mat4) *Mat4 {
 

gglm/quat.go

@@ -16,6 +16,37 @@ func (q *Quat) Eq(q2 *Quat) bool {
 	return q.Data == q2.Data
 }
 
+//Angle returns the angle represented by this quaternion
+func (q *Quat) Angle() float32 {
+
+	if Abs32(q.Data[3]) > CosHalf {
+
+		a := Asin32(Sqrt32(q.Data[0]*q.Data[0]+q.Data[1]*q.Data[1]+q.Data[2]*q.Data[2])) * 2
+		if q.Data[3] < 0 {
+			return Pi*2 - a
+		}
+		return a
+	}
+
+	return Acos32(q.Data[3]) * 2
+}
+
+//Axis returns the rotation axis represented by this quaternion
+func (q *Quat) Axis() *Vec3 {
+
+	var t float32 = 1 - q.Data[3]*q.Data[3]
+	if t <= 0 {
+		return &Vec3{Data: [3]float32{0, 0, 1}}
+	}
+
+	t = 1 / Sqrt32(t)
+	return &Vec3{Data: [3]float32{
+		q.Data[0] * t,
+		q.Data[1] * t,
+		q.Data[2] * t,
+	}}
+}
+
 //Euler takes rotations in radians and produces a rotation that
 //rotates around the z-axis, y-axis and lastly x-axis.
 func NewQuatEuler(v *Vec3) *Quat {

gglm/quat_test.go

@@ -25,3 +25,51 @@ func TestNewQuatAngleAxis(t *testing.T) {
 		t.Errorf("Got: %v; Expected: %v", q.String(), ans.String())
 	}
 }
+
+func TestQuatAngle(t *testing.T) {
+
+	a := gglm.NewQuatAngleAxis(180*gglm.Deg2Rad, gglm.NewVec3(0, 1, 0)).Angle()
+	var ans float32 = 180.0 * gglm.Deg2Rad
+
+	if !gglm.EqF32(a, ans) {
+		t.Errorf("Got: %v; Expected: %v", a, ans)
+	}
+
+	a = gglm.NewQuatAngleAxis(90*gglm.Deg2Rad, gglm.NewVec3(1, 1, 0).Normalize()).Angle()
+	ans = 90 * gglm.Deg2Rad
+
+	if !gglm.EqF32(a, ans) {
+		t.Errorf("Got: %v; Expected: %v", a, ans)
+	}
+
+	a = gglm.NewQuatAngleAxis(125*gglm.Deg2Rad, gglm.NewVec3(1, 1, 0).Normalize()).Angle()
+	ans = 125 * gglm.Deg2Rad
+
+	if !gglm.EqF32(a, ans) {
+		t.Errorf("Got: %v; Expected: %v", a, ans)
+	}
+}
+
+func TestQuatAxis(t *testing.T) {
+
+	a := gglm.NewQuatAngleAxis(1, gglm.NewVec3(0, 1, 0)).Axis()
+	ans := gglm.NewVec3(0, 1, 0)
+
+	if !gglm.EqF32(a.X(), ans.X()) || !gglm.EqF32(a.Y(), ans.Y()) || !gglm.EqF32(a.Z(), ans.Z()) {
+		t.Errorf("Got: %v; Expected: %v", a.String(), ans.String())
+	}
+
+	a = gglm.NewQuatAngleAxis(1, gglm.NewVec3(1, 1, 0).Normalize()).Axis()
+	ans = gglm.NewVec3(1, 1, 0).Normalize()
+
+	if !gglm.EqF32(a.X(), ans.X()) || !gglm.EqF32(a.Y(), ans.Y()) || !gglm.EqF32(a.Z(), ans.Z()) {
+		t.Errorf("Got: %v; Expected: %v", a.String(), ans.String())
+	}
+
+	a = gglm.NewQuatAngleAxis(1, gglm.NewVec3(67, 46, 32).Normalize()).Axis()
+	ans = gglm.NewVec3(67, 46, 32).Normalize()
+
+	if !gglm.EqF32(a.X(), ans.X()) || !gglm.EqF32(a.Y(), ans.Y()) || !gglm.EqF32(a.Z(), ans.Z()) {
+		t.Errorf("Got: %v; Expected: %v", a.String(), ans.String())
+	}
+}

gglm/scalar.go

@@ -2,9 +2,6 @@ package gglm
 
 import "math"
 
-//F32Epsilon = 0.0000005
-const F32Epsilon float32 = 1e-6
-
 //EqF32 true if abs(f1-f2) <= F32Epsilon
 func EqF32(f1, f2 float32) bool {
 	return math.Abs(float64(f1-f2)) <= float64(F32Epsilon)
@@ -31,7 +28,27 @@ func Acos32(x float32) float32 {
 	return float32(math.Acos(float64(x)))
 }
 
+func Tan32(x float32) float32 {
+	return float32(math.Tan(float64(x)))
+}
+
+func Atan32(x float32) float32 {
+	return float32(math.Atan(float64(x)))
+}
+
+func Atan232(x, y float32) float32 {
+	return float32(math.Atan2(float64(y), float64(x)))
+}
+
 func Sincos32(x float32) (sinx, cosx float32) {
 	a, b := math.Sincos(float64(x))
 	return float32(a), float32(b)
 }
+
+func Abs32(x float32) float32 {
+	return float32(math.Abs(float64(x)))
+}
+
+func Sqrt32(x float32) float32 {
+	return float32(math.Sqrt(float64(x)))
+}

gglm/transform.go

@@ -13,18 +13,64 @@ type TrMat struct {
 	Mat4
 }
 
-//Translate adds the vector to the translation components of the transformation matrix
-func (t *TrMat) Translate(v *Vec3) {
+//Translate adds v to the translation components of the transformation matrix
+func (t *TrMat) Translate(v *Vec3) *TrMat {
 	t.Data[3][0] += v.Data[0]
 	t.Data[3][1] += v.Data[1]
 	t.Data[3][2] += v.Data[2]
+	return t
 }
 
-//Scale multiplies the vector by the scale components of the transformation matrix
-func (t *TrMat) Scale(v *Vec3) {
+//Scale multiplies the scale components of the transformation matrix by v
+func (t *TrMat) Scale(v *Vec3) *TrMat {
 	t.Data[0][0] *= v.Data[0]
 	t.Data[1][1] *= v.Data[1]
 	t.Data[2][2] *= v.Data[2]
+	return t
+}
+
+//Rotate takes a *normalized* axis and angles in radians to rotate around the given axis
+func (t *TrMat) Rotate(rads float32, axis *Vec3) *TrMat {
+
+	s := Sin32(rads)
+	c := Cos32(rads)
+
+	axis = axis.Normalize()
+	temp := axis.Clone().Scale(1 - c)
+
+	rotate := TrMat{}
+	rotate.Data[0][0] = c + temp.Data[0]*axis.Data[0]
+	rotate.Data[0][1] = temp.Data[0]*axis.Data[1] + s*axis.Data[2]
+	rotate.Data[0][2] = temp.Data[0]*axis.Data[2] - s*axis.Data[1]
+
+	rotate.Data[1][0] = temp.Data[1]*axis.Data[0] - s*axis.Data[2]
+	rotate.Data[1][1] = c + temp.Data[1]*axis.Data[1]
+	rotate.Data[1][2] = temp.Data[1]*axis.Data[2] + s*axis.Data[0]
+
+	rotate.Data[2][0] = temp.Data[2]*axis.Data[0] + s*axis.Data[1]
+	rotate.Data[2][1] = temp.Data[2]*axis.Data[1] - s*axis.Data[0]
+	rotate.Data[2][2] = c + temp.Data[2]*axis.Data[2]
+
+	result := &Mat4{}
+	result.Data[0] = t.Col(0).Scale(rotate.Data[0][0]).
+		Add(t.Col(1).Scale(rotate.Data[0][1])).
+		Add(t.Col(2).Scale(rotate.Data[0][2])).
+		Data
+
+	result.Data[1] = t.Col(0).Scale(rotate.Data[1][0]).
+		Add(t.Col(1).Scale(rotate.Data[1][1])).
+		Add(t.Col(2).Scale(rotate.Data[1][2])).
+		Data
+
+	result.Data[2] = t.Col(0).Scale(rotate.Data[2][0]).
+		Add(t.Col(1).Scale(rotate.Data[2][1])).
+		Add(t.Col(2).Scale(rotate.Data[2][2])).
+		Data
+
+	t.Data[0] = result.Data[0]
+	t.Data[1] = result.Data[1]
+	t.Data[2] = result.Data[2]
+	return t
 }
 
 func (t *TrMat) Mul(m *TrMat) *TrMat {
@@ -136,7 +182,7 @@ func Ortho(left, right, top, bottom, nearClip, farClip float32) *TrMat {
 		Mat4: Mat4{
 			Data: [4][4]float32{
 				{2 / (right - left), 0, 0, 0},
-				{0, 2 / -(top - bottom), 0, 0},
+				{0, 2 / (top - bottom), 0, 0},
 				{0, 0, -2 / (farClip - nearClip), 0},
 				{-(right + left) / (right - left), -(top + bottom) / (top - bottom), -(farClip + nearClip) / (farClip - nearClip), 1},
 			},