542 lines
16 KiB
Go
542 lines
16 KiB
Go
// Package imdraw implements a basic primitive geometry shape and pictured polygon drawing for Pixel
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// with a nice immediate-mode-like API.
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package imdraw
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import (
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"image/color"
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"math"
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"github.com/faiface/pixel"
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)
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// IMDraw is an immediate-mode-like shape drawer and BasicTarget. IMDraw supports TrianglesPosition,
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// TrianglesColor, TrianglesPicture and PictureColor.
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//
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// IMDraw, other than a regular BasicTarget, is used to draw shapes. To draw shapes, you first need
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// to Push some points to IMDraw:
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//
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// imd := pixel.NewIMDraw(pic) // use nil pic if you only want to draw primitive shapes
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// imd.Push(pixel.V(100, 100))
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// imd.Push(pixel.V(500, 100))
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//
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// Once you have Pushed some points, you can use them to draw a shape, such as a line:
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//
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// imd.Line(20) // draws a 20 units thick line
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//
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// Use various methods to change properties of Pushed points:
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//
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// imd.Color(pixel.RGB(1, 0, 0))
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// imd.Push(pixel.V(200, 200))
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// imd.Circle(400, 0)
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//
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// Here is the list of all available point properties (need to be set before Pushing a point):
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// - Color - applies to all
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// - Picture - coordinates, only applies to filled polygons
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// - Intensity - picture intensity, only applies to filled polygons
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// - Precision - curve drawing precision, only applies to circles and ellipses
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// - EndShape - shape of the end of a line, only applies to lines and outlines
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//
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// And here's the list of all shapes that can be drawn (all, except for line, can be filled or
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// outlined):
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// - Line
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// - Polygon
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// - Circle
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// - Circle arc
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// - Ellipse
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// - Ellipse arc
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type IMDraw struct {
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points []point
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opts point
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matrix pixel.Matrix
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mask pixel.RGBA
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tri *pixel.TrianglesData
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batch *pixel.Batch
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}
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var _ pixel.BasicTarget = (*IMDraw)(nil)
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type point struct {
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pos pixel.Vec
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col pixel.RGBA
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pic pixel.Vec
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in float64
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precision int
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endshape EndShape
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}
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// EndShape specifies the shape of an end of a line or a curve.
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type EndShape int
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const (
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// NoEndShape leaves a line point with no special end shape.
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NoEndShape EndShape = iota
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// SharpEndShape is a sharp triangular end shape.
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SharpEndShape
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// RoundEndShape is a circular end shape.
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RoundEndShape
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)
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// New creates a new empty IMDraw. An optional Picture can be used to draw with a Picture.
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//
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// If you just want to draw primitive shapes, pass nil as the Picture.
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func New(pic pixel.Picture) *IMDraw {
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tri := &pixel.TrianglesData{}
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im := &IMDraw{
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tri: tri,
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batch: pixel.NewBatch(tri, pic),
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}
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im.SetMatrix(pixel.IM)
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im.SetColorMask(pixel.Alpha(1))
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im.Reset()
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return im
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}
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// Clear removes all drawn shapes from the IM. This does not remove Pushed points.
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func (imd *IMDraw) Clear() {
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imd.tri.SetLen(0)
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imd.batch.Dirty()
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}
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// Reset restores all point properties to defaults and removes all Pushed points.
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//
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// This does not affect matrix and color mask set by SetMatrix and SetColorMask.
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func (imd *IMDraw) Reset() {
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imd.points = nil
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imd.opts = point{}
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imd.Precision(64)
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}
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// Draw draws all currently drawn shapes inside the IM onto another Target.
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//
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// Note, that IMDraw's matrix and color mask have no effect here.
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func (imd *IMDraw) Draw(t pixel.Target) {
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imd.batch.Draw(t)
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}
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// Push adds some points to the IM queue. All Pushed points will have the same properties except for
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// the position.
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func (imd *IMDraw) Push(pts ...pixel.Vec) {
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for _, pt := range pts {
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imd.pushPt(pt, imd.opts)
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}
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}
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func (imd *IMDraw) pushPt(pos pixel.Vec, pt point) {
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pt.pos = pos
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imd.points = append(imd.points, pt)
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}
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// Color sets the color of the next Pushed points.
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func (imd *IMDraw) Color(color color.Color) {
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imd.opts.col = pixel.ToRGBA(color)
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}
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// Picture sets the Picture coordinates of the next Pushed points.
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func (imd *IMDraw) Picture(pic pixel.Vec) {
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imd.opts.pic = pic
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}
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// Intensity sets the picture Intensity of the next Pushed points.
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func (imd *IMDraw) Intensity(in float64) {
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imd.opts.in = in
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}
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// Precision sets the curve/circle drawing precision of the next Pushed points.
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//
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// It is the number of segments per 360 degrees.
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func (imd *IMDraw) Precision(p int) {
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imd.opts.precision = p
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}
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// EndShape sets the endshape of the next Pushed points.
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func (imd *IMDraw) EndShape(es EndShape) {
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imd.opts.endshape = es
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}
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// SetMatrix sets a Matrix that all further points will be transformed by.
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func (imd *IMDraw) SetMatrix(m pixel.Matrix) {
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imd.matrix = m
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imd.batch.SetMatrix(imd.matrix)
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}
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// SetColorMask sets a color that all further point's color will be multiplied by.
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func (imd *IMDraw) SetColorMask(color color.Color) {
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imd.mask = pixel.ToRGBA(color)
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imd.batch.SetColorMask(imd.mask)
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}
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// MakeTriangles returns a specialized copy of the provided Triangles that draws onto this IMDraw.
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func (imd *IMDraw) MakeTriangles(t pixel.Triangles) pixel.TargetTriangles {
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return imd.batch.MakeTriangles(t)
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}
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// MakePicture returns a specialized copy of the provided Picture that draws onto this IMDraw.
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func (imd *IMDraw) MakePicture(p pixel.Picture) pixel.TargetPicture {
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return imd.batch.MakePicture(p)
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}
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// Line draws a polyline of the specified thickness between the Pushed points.
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func (imd *IMDraw) Line(thickness float64) {
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imd.polyline(thickness, false)
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}
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// Polygon draws a polygon from the Pushed points. If the thickness is 0, the convex polygon will be
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// filled. Otherwise, an outline of the specified thickness will be drawn. The outline does not have
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// to be convex.
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//
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// Note, that the filled polygon does not have to be strictly convex. The way it's drawn is that a
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// triangle is drawn between each two adjacent points and the first Pushed point. You can use this
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// property to draw certain kinds of concave polygons.
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func (imd *IMDraw) Polygon(thickness float64) {
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if thickness == 0 {
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imd.fillPolygon()
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} else {
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imd.polyline(thickness, true)
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}
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}
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// Circle draws a circle of the specified radius around each Pushed point. If the thickness is 0,
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// the circle will be filled, otherwise a circle outline of the specified thickness will be drawn.
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func (imd *IMDraw) Circle(radius, thickness float64) {
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if thickness == 0 {
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imd.fillEllipseArc(pixel.V(radius, radius), 0, 2*math.Pi)
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} else {
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imd.outlineEllipseArc(pixel.V(radius, radius), 0, 2*math.Pi, thickness, false)
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}
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}
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// CircleArc draws a circle arc of the specified radius around each Pushed point. If the thickness
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// is 0, the arc will be filled, otherwise will be outlined. The arc starts at the low angle and
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// continues to the high angle. If low<high, the arc will be drawn counterclockwise. Otherwise it
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// will be clockwise. The angles are not normalized by any means.
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//
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// imd.CircleArc(40, 0, 8*math.Pi, 0)
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//
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// This line will fill the whole circle 4 times.
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func (imd *IMDraw) CircleArc(radius, low, high, thickness float64) {
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if thickness == 0 {
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imd.fillEllipseArc(pixel.V(radius, radius), low, high)
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} else {
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imd.outlineEllipseArc(pixel.V(radius, radius), low, high, thickness, true)
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}
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}
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// Ellipse draws an ellipse of the specified radius in each axis around each Pushed points. If the
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// thickness is 0, the ellipse will be filled, otherwise an ellipse outline of the specified
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// thickness will be drawn.
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func (imd *IMDraw) Ellipse(radius pixel.Vec, thickness float64) {
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if thickness == 0 {
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imd.fillEllipseArc(radius, 0, 2*math.Pi)
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} else {
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imd.outlineEllipseArc(radius, 0, 2*math.Pi, thickness, false)
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}
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}
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// EllipseArc draws an ellipse arc of the specified radius in each axis around each Pushed point. If
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// the thickness is 0, the arc will be filled, otherwise will be outlined. The arc starts at the low
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// angle and continues to the high angle. If low<high, the arc will be drawn counterclockwise.
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// Otherwise it will be clockwise. The angles are not normalized by any means.
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//
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// imd.EllipseArc(pixel.V(100, 50), 0, 8*math.Pi, 0)
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//
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// This line will fill the whole ellipse 4 times.
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func (imd *IMDraw) EllipseArc(radius pixel.Vec, low, high, thickness float64) {
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if thickness == 0 {
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imd.fillEllipseArc(radius, low, high)
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} else {
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imd.outlineEllipseArc(radius, low, high, thickness, true)
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}
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}
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func (imd *IMDraw) getAndClearPoints() []point {
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points := imd.points
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imd.points = nil
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return points
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}
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func (imd *IMDraw) applyMatrixAndMask(off int) {
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for i := range (*imd.tri)[off:] {
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(*imd.tri)[off+i].Position = imd.matrix.Project((*imd.tri)[off+i].Position)
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(*imd.tri)[off+i].Color = imd.mask.Mul((*imd.tri)[off+i].Color)
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}
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}
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func (imd *IMDraw) fillPolygon() {
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points := imd.getAndClearPoints()
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if len(points) < 3 {
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return
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}
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off := imd.tri.Len()
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imd.tri.SetLen(imd.tri.Len() + 3*(len(points)-2))
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for i, j := 1, off; i+1 < len(points); i, j = i+1, j+3 {
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(*imd.tri)[j+0].Position = points[0].pos
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(*imd.tri)[j+0].Color = points[0].col
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(*imd.tri)[j+0].Picture = points[0].pic
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(*imd.tri)[j+0].Intensity = points[0].in
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(*imd.tri)[j+1].Position = points[i].pos
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(*imd.tri)[j+1].Color = points[i].col
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(*imd.tri)[j+1].Picture = points[i].pic
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(*imd.tri)[j+1].Intensity = points[i].in
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(*imd.tri)[j+2].Position = points[i+1].pos
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(*imd.tri)[j+2].Color = points[i+1].col
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(*imd.tri)[j+2].Picture = points[i+1].pic
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(*imd.tri)[j+2].Intensity = points[i+1].in
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}
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imd.applyMatrixAndMask(off)
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imd.batch.Dirty()
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}
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func (imd *IMDraw) fillEllipseArc(radius pixel.Vec, low, high float64) {
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points := imd.getAndClearPoints()
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for _, pt := range points {
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num := math.Ceil(math.Abs(high-low) / (2 * math.Pi) * float64(pt.precision))
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delta := (high - low) / num
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off := imd.tri.Len()
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imd.tri.SetLen(imd.tri.Len() + 3*int(num))
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for i := range (*imd.tri)[off:] {
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(*imd.tri)[off+i].Color = pt.col
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(*imd.tri)[off+i].Picture = 0
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(*imd.tri)[off+i].Intensity = 0
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}
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for i, j := 0.0, off; i < num; i, j = i+1, j+3 {
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angle := low + i*delta
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sin, cos := math.Sincos(angle)
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a := pt.pos + pixel.V(
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radius.X()*cos,
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radius.Y()*sin,
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)
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angle = low + (i+1)*delta
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sin, cos = math.Sincos(angle)
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b := pt.pos + pixel.V(
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radius.X()*cos,
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radius.Y()*sin,
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)
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(*imd.tri)[j+0].Position = pt.pos
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(*imd.tri)[j+1].Position = a
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(*imd.tri)[j+2].Position = b
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}
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imd.applyMatrixAndMask(off)
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imd.batch.Dirty()
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}
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}
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func (imd *IMDraw) outlineEllipseArc(radius pixel.Vec, low, high, thickness float64, doEndShape bool) {
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points := imd.getAndClearPoints()
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for _, pt := range points {
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num := math.Ceil(math.Abs(high-low) / (2 * math.Pi) * float64(pt.precision))
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delta := (high - low) / num
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off := imd.tri.Len()
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imd.tri.SetLen(imd.tri.Len() + 6*int(num))
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for i := range (*imd.tri)[off:] {
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(*imd.tri)[off+i].Color = pt.col
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(*imd.tri)[off+i].Picture = 0
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(*imd.tri)[off+i].Intensity = 0
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}
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for i, j := 0.0, off; i < num; i, j = i+1, j+6 {
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angle := low + i*delta
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sin, cos := math.Sincos(angle)
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normalSin, normalCos := pixel.V(sin, cos).ScaledXY(radius).Unit().XY()
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a := pt.pos + pixel.V(
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radius.X()*cos-thickness/2*normalCos,
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radius.Y()*sin-thickness/2*normalSin,
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)
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b := pt.pos + pixel.V(
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radius.X()*cos+thickness/2*normalCos,
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radius.Y()*sin+thickness/2*normalSin,
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)
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angle = low + (i+1)*delta
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sin, cos = math.Sincos(angle)
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normalSin, normalCos = pixel.V(sin, cos).ScaledXY(radius).Unit().XY()
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c := pt.pos + pixel.V(
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radius.X()*cos-thickness/2*normalCos,
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radius.Y()*sin-thickness/2*normalSin,
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)
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d := pt.pos + pixel.V(
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radius.X()*cos+thickness/2*normalCos,
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radius.Y()*sin+thickness/2*normalSin,
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)
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(*imd.tri)[j+0].Position = a
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(*imd.tri)[j+1].Position = b
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(*imd.tri)[j+2].Position = c
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(*imd.tri)[j+3].Position = c
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(*imd.tri)[j+4].Position = b
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(*imd.tri)[j+5].Position = d
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}
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imd.applyMatrixAndMask(off)
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imd.batch.Dirty()
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if doEndShape {
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lowSin, lowCos := math.Sincos(low)
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lowCenter := pt.pos + pixel.V(
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radius.X()*lowCos,
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radius.Y()*lowSin,
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)
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normalLowSin, normalLowCos := pixel.V(lowSin, lowCos).ScaledXY(radius).Unit().XY()
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normalLow := pixel.V(normalLowCos, normalLowSin).Angle()
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highSin, highCos := math.Sincos(high)
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highCenter := pt.pos + pixel.V(
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radius.X()*highCos,
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radius.Y()*highSin,
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)
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normalHighSin, normalHighCos := pixel.V(highSin, highCos).ScaledXY(radius).Unit().XY()
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normalHigh := pixel.V(normalHighCos, normalHighSin).Angle()
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orientation := 1.0
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if low > high {
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orientation = -1.0
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}
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switch pt.endshape {
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case NoEndShape:
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// nothing
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case SharpEndShape:
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thick := pixel.X(thickness / 2).Rotated(normalLow)
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imd.pushPt(lowCenter+thick, pt)
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imd.pushPt(lowCenter-thick, pt)
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imd.pushPt(lowCenter-thick.Rotated(math.Pi/2*orientation), pt)
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imd.fillPolygon()
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thick = pixel.X(thickness / 2).Rotated(normalHigh)
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imd.pushPt(highCenter+thick, pt)
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imd.pushPt(highCenter-thick, pt)
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imd.pushPt(highCenter+thick.Rotated(math.Pi/2*orientation), pt)
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imd.fillPolygon()
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case RoundEndShape:
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imd.pushPt(lowCenter, pt)
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imd.fillEllipseArc(pixel.V(thickness, thickness)/2, normalLow, normalLow-math.Pi*orientation)
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imd.pushPt(highCenter, pt)
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imd.fillEllipseArc(pixel.V(thickness, thickness)/2, normalHigh, normalHigh+math.Pi*orientation)
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}
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}
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}
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}
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func (imd *IMDraw) polyline(thickness float64, closed bool) {
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points := imd.getAndClearPoints()
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if len(points) == 0 {
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return
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}
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if len(points) == 1 {
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// one point special case
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points = append(points, points[0])
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}
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// first point
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j, i := 0, 1
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normal := (points[i].pos - points[j].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
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if !closed {
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switch points[j].endshape {
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case NoEndShape:
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// nothing
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case SharpEndShape:
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imd.pushPt(points[j].pos+normal, points[j])
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imd.pushPt(points[j].pos-normal, points[j])
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imd.pushPt(points[j].pos+normal.Rotated(math.Pi/2), points[j])
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imd.fillPolygon()
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case RoundEndShape:
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imd.pushPt(points[j].pos, points[j])
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imd.fillEllipseArc(pixel.V(thickness, thickness)/2, normal.Angle(), normal.Angle()+math.Pi)
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}
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}
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imd.pushPt(points[j].pos+normal, points[j])
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imd.pushPt(points[j].pos-normal, points[j])
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// middle points
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for i := 0; i < len(points); i++ {
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j, k := i+1, i+2
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closing := false
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if j >= len(points) {
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if !closed {
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break
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}
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j %= len(points)
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closing = true
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}
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if k >= len(points) {
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k %= len(points)
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}
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ijNormal := (points[j].pos - points[i].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
|
|
jkNormal := (points[k].pos - points[j].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
|
|
|
|
orientation := 1.0
|
|
if ijNormal.Cross(jkNormal) > 0 {
|
|
orientation = -1.0
|
|
}
|
|
|
|
imd.pushPt(points[j].pos-ijNormal, points[j])
|
|
imd.pushPt(points[j].pos+ijNormal, points[j])
|
|
imd.fillPolygon()
|
|
|
|
switch points[j].endshape {
|
|
case NoEndShape:
|
|
// nothing
|
|
case SharpEndShape:
|
|
imd.pushPt(points[j].pos, points[j])
|
|
imd.pushPt(points[j].pos+ijNormal.Scaled(orientation), points[j])
|
|
imd.pushPt(points[j].pos+jkNormal.Scaled(orientation), points[j])
|
|
imd.fillPolygon()
|
|
case RoundEndShape:
|
|
imd.pushPt(points[j].pos, points[j])
|
|
imd.fillEllipseArc(pixel.V(thickness, thickness)/2, ijNormal.Angle(), ijNormal.Angle()-math.Pi)
|
|
imd.pushPt(points[j].pos, points[j])
|
|
imd.fillEllipseArc(pixel.V(thickness, thickness)/2, jkNormal.Angle(), jkNormal.Angle()+math.Pi)
|
|
}
|
|
|
|
if !closing {
|
|
imd.pushPt(points[j].pos+jkNormal, points[j])
|
|
imd.pushPt(points[j].pos-jkNormal, points[j])
|
|
}
|
|
}
|
|
|
|
// last point
|
|
i, j = len(points)-2, len(points)-1
|
|
normal = (points[j].pos - points[i].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
|
|
|
|
imd.pushPt(points[j].pos-normal, points[j])
|
|
imd.pushPt(points[j].pos+normal, points[j])
|
|
imd.fillPolygon()
|
|
|
|
if !closed {
|
|
switch points[j].endshape {
|
|
case NoEndShape:
|
|
// nothing
|
|
case SharpEndShape:
|
|
imd.pushPt(points[j].pos+normal, points[j])
|
|
imd.pushPt(points[j].pos-normal, points[j])
|
|
imd.pushPt(points[j].pos+normal.Rotated(-math.Pi/2), points[j])
|
|
imd.fillPolygon()
|
|
case RoundEndShape:
|
|
imd.pushPt(points[j].pos, points[j])
|
|
imd.fillEllipseArc(pixel.V(thickness, thickness)/2, normal.Angle(), normal.Angle()-math.Pi)
|
|
}
|
|
}
|
|
}
|