ebiten/affine.go
2016-04-11 01:48:40 +09:00

72 lines
1.7 KiB
Go

// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ebiten
type affine interface {
dim() int
Element(i, j int) float64
SetElement(i, j int, element float64)
}
func isIdentity(ebiten affine) bool {
dim := ebiten.dim()
for i := 0; i < dim-1; i++ {
for j := 0; j < dim; j++ {
element := ebiten.Element(i, j)
if i == j && element != 1 {
return false
} else if i != j && element != 0 {
return false
}
}
}
return true
}
func add(lhs, rhs, result affine) {
dim := lhs.dim()
if dim != rhs.dim() {
panic("ebiten: diffrent-sized matrices can't be multiplied")
}
for i := 0; i < dim-1; i++ {
for j := 0; j < dim; j++ {
v := lhs.Element(i, j) + rhs.Element(i, j)
result.SetElement(i, j, v)
}
}
}
func mul(lhs, rhs, result affine) {
dim := lhs.dim()
if dim != rhs.dim() {
panic("ebiten: 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)
}
}
}