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// 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
}
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