Adding upstream version 0.0~git20250520.a1d9079+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

exp/f32/mat3.go

@@ -0,0 +1,63 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package f32
+
+import "fmt"
+
+// A Mat3 is a 3x3 matrix of float32 values.
+// Elements are indexed first by row then column, i.e. m[row][column].
+type Mat3 [3]Vec3
+
+func (m Mat3) String() string {
+	return fmt.Sprintf(`Mat3[% 0.3f, % 0.3f, % 0.3f,
+     % 0.3f, % 0.3f, % 0.3f,
+     % 0.3f, % 0.3f, % 0.3f]`,
+		m[0][0], m[0][1], m[0][2],
+		m[1][0], m[1][1], m[1][2],
+		m[2][0], m[2][1], m[2][2])
+}
+
+func (m *Mat3) Identity() {
+	*m = Mat3{
+		{1, 0, 0},
+		{0, 1, 0},
+		{0, 0, 1},
+	}
+}
+
+func (m *Mat3) Eq(n *Mat3, epsilon float32) bool {
+	for i := range m {
+		for j := range m[i] {
+			diff := m[i][j] - n[i][j]
+			if diff < -epsilon || +epsilon < diff {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Mul stores a × b in m.
+func (m *Mat3) Mul(a, b *Mat3) {
+	// Store the result in local variables, in case m == a || m == b.
+	m00 := a[0][0]*b[0][0] + a[0][1]*b[1][0] + a[0][2]*b[2][0]
+	m01 := a[0][0]*b[0][1] + a[0][1]*b[1][1] + a[0][2]*b[2][1]
+	m02 := a[0][0]*b[0][2] + a[0][1]*b[1][2] + a[0][2]*b[2][2]
+	m10 := a[1][0]*b[0][0] + a[1][1]*b[1][0] + a[1][2]*b[2][0]
+	m11 := a[1][0]*b[0][1] + a[1][1]*b[1][1] + a[1][2]*b[2][1]
+	m12 := a[1][0]*b[0][2] + a[1][1]*b[1][2] + a[1][2]*b[2][2]
+	m20 := a[2][0]*b[0][0] + a[2][1]*b[1][0] + a[2][2]*b[2][0]
+	m21 := a[2][0]*b[0][1] + a[2][1]*b[1][1] + a[2][2]*b[2][1]
+	m22 := a[2][0]*b[0][2] + a[2][1]*b[1][2] + a[2][2]*b[2][2]
+	m[0][0] = m00
+	m[0][1] = m01
+	m[0][2] = m02
+	m[1][0] = m10
+	m[1][1] = m11
+	m[1][2] = m12
+	m[2][0] = m20
+	m[2][1] = m21
+	m[2][2] = m22
+}