ebiten/graphics/matrix/affine.go

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2013-06-20 18:47:39 +02:00
package matrix
type Affine interface {
Dim() int
element(i, j int) float64
setElement(i, j int, element float64)
}
func isIdentity(matrix Affine) bool {
dim := matrix.Dim()
for i := 0; i < dim-1; i++ {
for j := 0; j < dim; j++ {
element := matrix.element(i, j)
if i == j && element != 1 {
return false
} else if i != j && element != 0 {
return false
}
}
}
return true
}
func mul(lhs, rhs, result Affine) {
dim := lhs.Dim()
if dim != rhs.Dim() {
panic("diffrent-sized matrices can't be multiplied")
}
for i := 0; i < dim-1; i++ {
for j := 0; j < dim; j++ {
element := float64(0)
for k := 0; k < dim-1; k++ {
element += lhs.element(i, k) *
rhs.element(k, j)
}
if j == dim-1 {
element += lhs.element(i, j)
}
result.setElement(i, j, element)
}
}
}