refactor transform module
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legoff.laurent
parent
ae9b990671
commit
5e6aa57cf2
3 changed files with 48 additions and 72 deletions
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@ -446,7 +446,7 @@ func TestTransform() {
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gc.Save()
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gc.Translate(100, 150) // Translate origin to (100, 150)
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gc.Rotate(30* (math.Pi / 180.0)) // Rotate counter-clockwise by 30 degrees
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gc.Rotate(30* (math.Pi / 180.0)) // Rotate counter-clockwise by 30 degrees
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gc.BeginPath()
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gc.MoveTo(0,0)
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gc.RLineTo(72,0)
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@ -470,7 +470,7 @@ func TestTransform() {
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gc.Save()
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gc.Translate(300, 300) // Set origin to (300, 300)
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gc.Rotate(45* (math.Pi / 180.0)) // Rotate coordinates by 45 degrees
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gc.Rotate(45* (math.Pi / 180.0)) // Rotate coordinates by 45 degrees
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gc.Scale(0.5, 1) // Scale coordinates
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gc.BeginPath()
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gc.MoveTo(0,0)
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@ -6,6 +6,7 @@ package draw2d
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import (
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"exp/draw"
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"image"
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//"math"
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"freetype-go.googlecode.com/hg/freetype/raster"
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)
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@ -79,28 +80,19 @@ func (gc *GraphicContext) SetMatrixTransform(tr MatrixTransform) {
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}
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func (gc *GraphicContext) ComposeMatrixTransform(tr MatrixTransform) {
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gc.current.tr.Compose(tr)
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gc.current.tr = tr.Multiply(gc.current.tr)
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}
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func (gc *GraphicContext) Rotate(angle float) {
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ox, oy := gc.current.path.LastPoint()
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tr := NewTranslationMatrix(ox, oy)
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tr2 := NewRotationMatrix(angle)
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tr1 := tr.GetInverseTransformation()
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gc.current.tr.Compose(tr).Compose(tr2).Compose(tr1)
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gc.current.tr.Rotate(angle)
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}
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func (gc *GraphicContext) Translate(tx, ty float) {
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tr := NewTranslationMatrix(tx, ty)
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gc.current.tr.Compose(tr)
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gc.current.tr.Translate(tx, ty)
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}
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func (gc *GraphicContext) Scale(sx, sy float) {
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ox, oy := gc.current.path.LastPoint()
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tr := NewTranslationMatrix(ox, oy)
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tr2 := NewScaleMatrix(sx, sy)
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tr1 := tr.GetInverseTransformation()
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gc.current.tr.Compose(tr).Compose(tr2).Compose(tr1)
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gc.current.tr.Scale(sx, sy)
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}
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func (gc *GraphicContext) Clear() {
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@ -9,36 +9,19 @@ const (
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epsilon = 1e-6
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)
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func (tr MatrixTransform) TransformX(x, y float) float {
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return x*tr[0] + y*tr[2] + tr[4]
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}
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func (tr MatrixTransform) TransformY(x, y float) float {
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return x*tr[1] + y*tr[3] + tr[5]
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}
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func (tr MatrixTransform) Determinant() float {
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return tr[0]*tr[3] - tr[1]*tr[2]
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}
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func (tr MatrixTransform) InverseTransformX(x, y float) float {
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return ((x-tr[4])*tr[3] - (y-tr[5])*tr[2]) / tr.Determinant()
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}
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func (tr MatrixTransform) InverseTransformY(x, y float) float {
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return ((y-tr[5])*tr[0] - (x-tr[4])*tr[1]) / tr.Determinant()
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}
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func (tr MatrixTransform) Transform(points ...*float) {
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for i, j := 0, 1; j < len(points); i, j = i+2, j+2 {
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x := *points[i]
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y := *points[j]
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*points[i] = tr.TransformX(x, y)
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*points[j] = tr.TransformY(x, y)
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*points[i] = x*tr[0] + y*tr[2] + tr[4]
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*points[j] = x*tr[1] + y*tr[3] + tr[5]
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}
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}
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func (tr MatrixTransform) InverseTransform(points ...*float) {
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d := tr.Determinant() // matrix determinant
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for i, j := 0, 1; j < len(points); i, j = i+2, j+2 {
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@ -51,30 +34,12 @@ func (tr MatrixTransform) InverseTransform(points ...*float) {
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// ******************** Vector transformations ********************
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func (tr MatrixTransform) VectorTransformX(x, y float) float {
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return x*tr[0] + y*tr[2]
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}
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func (tr MatrixTransform) VectorTransformY(x, y float) float {
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return x*tr[1] + y*tr[3]
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}
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func (tr MatrixTransform) VectorInverseTransformX(x, y float) float {
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d := tr.Determinant() // matrix determinant
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return (x*tr[3] - y*tr[2]) / d
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}
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func (tr MatrixTransform) VectorInverseTransformY(x, y float) float {
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d := tr.Determinant() // matrix determinant
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return (y*tr[0] - x*tr[1]) / d
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}
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func (tr MatrixTransform) VectorTransform(points ...*float) {
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for i, j := 0, 1; j < len(points); i, j = i+2, j+2 {
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x := *points[i]
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y := *points[j]
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*points[i] = tr.VectorTransformX(x, y)
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*points[j] = tr.VectorTransformY(x, y)
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*points[i] = x*tr[0] + y*tr[2]
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*points[j] = x*tr[1] + y*tr[3]
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}
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}
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@ -112,7 +77,7 @@ func NewRotationMatrix(angle float) MatrixTransform {
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/**
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* Creates a transformation, combining a scale and a translation, that transform rectangle1 into rectangle2.
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*/
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func NewMatrixTransform(rectangle1 [4]float, rectangle2 [4]float) MatrixTransform {
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func NewMatrixTransform(rectangle1, rectangle2 [4]float) MatrixTransform {
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xScale := (rectangle2[2] - rectangle2[0]) / (rectangle1[2] - rectangle1[0])
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yScale := (rectangle2[3] - rectangle2[1]) / (rectangle1[3] - rectangle1[1])
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xOffset := rectangle2[0] - (rectangle1[0] * xScale)
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@ -136,15 +101,8 @@ func (tr MatrixTransform) GetInverseTransformation() MatrixTransform {
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(tr[1]*tr[4] - tr[0]*tr[5]) / d}
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}
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/**
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* Returns a transformation that is the composition (tr2 o tr1) of the given
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* transformations tr2 and tr1.
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* For given point (x, y), the composed transformation is defined by the
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* equation:
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* (tr2 o tr1)(x, y) = tr2(tr1(x, y))
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*/
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func (tr1 MatrixTransform) GetComposedTransformation(tr2 MatrixTransform) MatrixTransform {
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func (tr1 MatrixTransform) Multiply(tr2 MatrixTransform) MatrixTransform {
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return [6]float{
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tr1[0]*tr2[0] + tr1[1]*tr2[2],
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tr1[1]*tr2[3] + tr1[0]*tr2[1],
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@ -154,14 +112,40 @@ func (tr1 MatrixTransform) GetComposedTransformation(tr2 MatrixTransform) Matrix
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tr1[5]*tr2[3] + tr1[4]*tr2[1] + tr2[5]}
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}
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func (tr1 *MatrixTransform) Compose(tr2 MatrixTransform) (*MatrixTransform){
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tr1[0] = tr2[0]*tr1[0] + tr2[1]*tr1[2]
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tr1[1] = tr2[1]*tr1[3] + tr2[0]*tr1[1]
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tr1[2] = tr2[2]*tr1[0] + tr2[3]*tr1[2]
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tr1[3] = tr2[3]*tr1[3] + tr2[2]*tr1[1]
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tr1[4] = tr2[4]*tr1[0] + tr2[5]*tr1[2] + tr1[4]
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tr1[5] = tr2[5]*tr1[3] + tr2[4]*tr1[1] + tr1[5]
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return tr1
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func (tr *MatrixTransform) Scale(sx, sy float) (*MatrixTransform){
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tr[0] = tr[0]*sx;
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tr[1] = tr[1]*sx;
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tr[4] = tr[4]*sx;
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tr[2] = tr[2]*sy;
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tr[3] = tr[3]*sy;
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tr[5] = tr[5]*sy;
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return tr;
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}
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func (tr *MatrixTransform) Translate(tx, ty float) (*MatrixTransform){
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tr[4] = tr[4] + tx
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tr[5] = tr[5] + ty
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return tr;
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}
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func (tr *MatrixTransform) Rotate(angle float) (*MatrixTransform){
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ca := cos(angle);
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sa := sin(angle);
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t0 := tr[0] * ca - tr[1] * sa;
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t2 := tr[1] * ca - tr[3] * sa;
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t4 := tr[4] * ca - tr[5] * sa;
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tr[1] = tr[0] * sa + tr[1] * ca;
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tr[3] = tr[2] * sa + tr[3] * ca;
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tr[5] = tr[4] * sa + tr[5] * ca;
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tr[0] = t0;
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tr[2] = t2;
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tr[4] = t4;
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return tr;
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}
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func (tr MatrixTransform) GetTranslation() (x, y float) {
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return tr[4], tr[5]
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}
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// ******************** Testing ********************
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