89 lines
1.3 KiB
Go
89 lines
1.3 KiB
Go
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package gg
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import "math"
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type Matrix struct {
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XX, YX, XY, YY, X0, Y0 float64
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}
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func Identity() Matrix {
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return Matrix{
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1, 0,
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0, 1,
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0, 0,
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}
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}
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func Translate(x, y float64) Matrix {
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return Matrix{
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1, 0,
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0, 1,
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x, y,
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}
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}
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func Scale(x, y float64) Matrix {
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return Matrix{
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x, 0,
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0, y,
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0, 0,
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}
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}
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func Rotate(angle float64) Matrix {
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c := math.Cos(angle)
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s := math.Sin(angle)
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return Matrix{
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c, s,
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-s, c,
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0, 0,
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}
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}
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func Shear(x, y float64) Matrix {
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return Matrix{
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1, y,
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x, 1,
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0, 0,
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}
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}
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func (a Matrix) Multiply(b Matrix) Matrix {
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return Matrix{
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a.XX*b.XX + a.YX*b.XY,
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a.XX*b.YX + a.YX*b.YY,
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a.XY*b.XX + a.YY*b.XY,
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a.XY*b.YX + a.YY*b.YY,
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a.X0*b.XX + a.Y0*b.XY + b.X0,
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a.X0*b.YX + a.Y0*b.YY + b.Y0,
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}
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}
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func (a Matrix) TransformVector(x, y float64) (tx, ty float64) {
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tx = a.XX*x + a.XY*y
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ty = a.YX*x + a.YY*y
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return
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}
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func (a Matrix) TransformPoint(x, y float64) (tx, ty float64) {
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tx = a.XX*x + a.XY*y + a.X0
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ty = a.YX*x + a.YY*y + a.Y0
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return
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}
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func (a Matrix) Translate(x, y float64) Matrix {
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return Translate(x, y).Multiply(a)
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}
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func (a Matrix) Scale(x, y float64) Matrix {
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return Scale(x, y).Multiply(a)
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}
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func (a Matrix) Rotate(angle float64) Matrix {
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return Rotate(angle).Multiply(a)
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}
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func (a Matrix) Shear(x, y float64) Matrix {
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return Shear(x, y).Multiply(a)
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}
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