ebiten/graphics/matrix/geometry.go
2013-06-21 01:47:39 +09:00

60 lines
1.0 KiB
Go

package matrix
import (
"math"
)
const geometryDim = 3
type Geometry struct {
Elements [geometryDim - 1][geometryDim]float64
}
func IdentityGeometry() Geometry {
return Geometry{
[geometryDim - 1][geometryDim]float64{
{1, 0, 0},
{0, 1, 0},
},
}
}
func (matrix *Geometry) Dim() int {
return geometryDim
}
func (matrix *Geometry) Concat(other Geometry) {
result := Geometry{}
mul(&other, matrix, &result)
*matrix = result
}
func (matrix *Geometry) IsIdentity() bool {
return isIdentity(matrix)
}
func (matrix *Geometry) element(i, j int) float64 {
return matrix.Elements[i][j]
}
func (matrix *Geometry) setElement(i, j int, element float64) {
matrix.Elements[i][j] = element
}
func (matrix *Geometry) Translate(tx, ty float64) {
matrix.Elements[0][2] += tx
matrix.Elements[1][2] += ty
}
func (matrix *Geometry) Rotate(theta float64) {
cos := math.Cos(theta)
sin := math.Sin(theta)
rotate := Geometry{
[2][3]float64{
{cos, -sin, 0},
{sin, cos, 0},
},
}
matrix.Concat(rotate)
}