backport imgui goodies from gl02

internal/util/itype/vec.go

@@ -49,6 +49,33 @@ func (v Vec4i) MultiplyInt(mult int) Vec4i {
 // Vec2f is a two-element float vector
 type Vec2f [2]float32
 
+func (v Vec2f) Add(add Vec2f) Vec2f {
+	return Vec2f{v[0] + add[0], v[1] + add[1]}
+}
+
+func (v Vec2f) Addv(x, y float32) Vec2f {
+	return Vec2f{v[0] + x, v[1] + y}
+}
+
+func (v Vec2f) Floor() Vec2i {
+	return Vec2i{
+		int(math.Floor(float64(v[0]))),
+		int(math.Floor(float64(v[1]))),
+	}
+}
+func (v Vec2f) Length() float32 {
+	return float32(math.Sqrt(float64(v[0]*v[0] + v[1]*v[1])))
+}
+
+func (v Vec2f) Normalize() Vec2f {
+	l := v.Length()
+	return Vec2f{v[0] / l, v[1] / l}
+}
+
+func (v Vec2f) ToFloat64() Vec2d {
+	return Vec2d{float64(v[0]), float64(v[1])}
+}
+
 // Vec3f is a three-element float vector
 type Vec3f [3]float32
 
@@ -91,6 +118,37 @@ type Vec4f [4]float32
 // Vec2d is a two-element float64 vector
 type Vec2d [2]float64
 
+func (v Vec2d) Add(add Vec2d) Vec2d {
+	return Vec2d{v[0] + add[0], v[1] + add[1]}
+}
+
+func (v Vec2d) Addv(x, y float64) Vec2d {
+	return Vec2d{v[0] + x, v[1] + y}
+}
+
+func (v Vec2d) Multiply(x float64) Vec2d {
+	return Vec2d{v[0] * x, v[1] * x}
+}
+
+func (v Vec2d) Floor() Vec2i {
+	return Vec2i{
+		int(math.Floor(float64(v[0]))),
+		int(math.Floor(float64(v[1]))),
+	}
+}
+func (v Vec2d) Length() float64 {
+	return math.Sqrt(v[0]*v[0] + v[1]*v[1])
+}
+
+func (v Vec2d) Normalize() Vec2d {
+	l := v.Length()
+	return Vec2d{v[0] / l, v[1] / l}
+}
+
+func (v Vec2d) ToFloat32() Vec2f {
+	return Vec2f{float32(v[0]), float32(v[1])}
+}
+
 // Vec3d is a three-element float64 vector
 type Vec3d [3]float64