package shapes import "math" import "image" import "image/color" import "git.tebibyte.media/sashakoshka/tomo/artist" // TODO: redo fill ellipse, stroke ellipse, etc. so that it only takes in // destination and source, using the bounds of destination as the bounds of the // ellipse and the bounds of source as the "clipping rectangle". Line up the Min // of both canvases. func FillEllipse ( destination artist.Canvas, source artist.Canvas, bounds image.Rectangle, ) ( updatedRegion image.Rectangle, ) { dstData, dstStride := destination.Buffer() srcData, srcStride := source.Buffer() offset := source.Bounds().Min.Sub(destination.Bounds().Min) drawBounds := source.Bounds().Sub(offset). Intersect(destination.Bounds()). Intersect(bounds) if bounds.Empty() { return } updatedRegion = bounds point := image.Point { } for point.Y = drawBounds.Min.Y; point.Y < drawBounds.Max.Y; point.Y ++ { for point.X = drawBounds.Min.X; point.X < drawBounds.Max.X; point.X ++ { if inEllipse(point, bounds) { offsetPoint := point.Add(offset) dstIndex := point.X + point.Y * dstStride srcIndex := offsetPoint.X + offsetPoint.Y * srcStride dstData[dstIndex] = srcData[srcIndex] } }} return } func StrokeEllipse ( destination artist.Canvas, source artist.Canvas, bounds image.Rectangle, weight int, ) { if weight < 1 { return } dstData, dstStride := destination.Buffer() srcData, srcStride := source.Buffer() drawBounds := destination.Bounds().Inset(weight - 1) offset := source.Bounds().Min.Sub(destination.Bounds().Min) if drawBounds.Empty() { return } context := ellipsePlottingContext { plottingContext: plottingContext { dstData: dstData, dstStride: dstStride, srcData: srcData, srcStride: srcStride, weight: weight, offset: offset, bounds: bounds, }, radii: image.Pt(drawBounds.Dx() / 2, drawBounds.Dy() / 2), } context.center = drawBounds.Min.Add(context.radii) context.plotEllipse() } type ellipsePlottingContext struct { plottingContext radii image.Point center image.Point } func (context ellipsePlottingContext) plotEllipse () { x := float64(0) y := float64(context.radii.Y) // region 1 decision parameter decision1 := float64(context.radii.Y * context.radii.Y) - float64(context.radii.X * context.radii.X * context.radii.Y) + (0.25 * float64(context.radii.X) * float64(context.radii.X)) decisionX := float64(2 * context.radii.Y * context.radii.Y * int(x)) decisionY := float64(2 * context.radii.X * context.radii.X * int(y)) // draw region 1 for decisionX < decisionY { points := []image.Point { image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y), image.Pt( int(x) + context.center.X, -int(y) + context.center.Y), image.Pt(-int(x) + context.center.X, int(y) + context.center.Y), image.Pt( int(x) + context.center.X, int(y) + context.center.Y), } if context.srcData == nil { context.plotColor(points[0]) context.plotColor(points[1]) context.plotColor(points[2]) context.plotColor(points[3]) } else { context.plotSource(points[0]) context.plotSource(points[1]) context.plotSource(points[2]) context.plotSource(points[3]) } if (decision1 < 0) { x ++ decisionX += float64(2 * context.radii.Y * context.radii.Y) decision1 += decisionX + float64(context.radii.Y * context.radii.Y) } else { x ++ y -- decisionX += float64(2 * context.radii.Y * context.radii.Y) decisionY -= float64(2 * context.radii.X * context.radii.X) decision1 += decisionX - decisionY + float64(context.radii.Y * context.radii.Y) } } // region 2 decision parameter decision2 := float64(context.radii.Y * context.radii.Y) * (x + 0.5) * (x + 0.5) + float64(context.radii.X * context.radii.X) * (y - 1) * (y - 1) - float64(context.radii.X * context.radii.X * context.radii.Y * context.radii.Y) // draw region 2 for y >= 0 { points := []image.Point { image.Pt( int(x) + context.center.X, int(y) + context.center.Y), image.Pt(-int(x) + context.center.X, int(y) + context.center.Y), image.Pt( int(x) + context.center.X, -int(y) + context.center.Y), image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y), } if context.srcData == nil { context.plotColor(points[0]) context.plotColor(points[1]) context.plotColor(points[2]) context.plotColor(points[3]) } else { context.plotSource(points[0]) context.plotSource(points[1]) context.plotSource(points[2]) context.plotSource(points[3]) } if decision2 > 0 { y -- decisionY -= float64(2 * context.radii.X * context.radii.X) decision2 += float64(context.radii.X * context.radii.X) - decisionY } else { y -- x ++ decisionX += float64(2 * context.radii.Y * context.radii.Y) decisionY -= float64(2 * context.radii.X * context.radii.X) decision2 += decisionX - decisionY + float64(context.radii.X * context.radii.X) } } } // FillColorEllipse fills an ellipse within the destination canvas with a solid // color. func FillColorEllipse ( destination artist.Canvas, color color.RGBA, bounds image.Rectangle, ) ( updatedRegion image.Rectangle, ) { dstData, dstStride := destination.Buffer() realBounds := bounds bounds = bounds.Intersect(destination.Bounds()).Canon() if bounds.Empty() { return } updatedRegion = bounds point := image.Point { } for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ { for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ { if inEllipse(point, realBounds) { dstData[point.X + point.Y * dstStride] = color } }} return } // StrokeColorEllipse is similar to FillColorEllipse, but it draws an inset // outline of an ellipse instead. func StrokeColorEllipse ( destination artist.Canvas, color color.RGBA, bounds image.Rectangle, weight int, ) ( updatedRegion image.Rectangle, ) { if weight < 1 { return } dstData, dstStride := destination.Buffer() insetBounds := bounds.Inset(weight - 1) context := ellipsePlottingContext { plottingContext: plottingContext { dstData: dstData, dstStride: dstStride, color: color, weight: weight, bounds: bounds.Intersect(destination.Bounds()), }, radii: image.Pt(insetBounds.Dx() / 2, insetBounds.Dy() / 2), } context.center = insetBounds.Min.Add(context.radii) context.plotEllipse() return } func inEllipse (point image.Point, bounds image.Rectangle) bool { point = point.Sub(bounds.Min) x := (float64(point.X) + 0.5) / float64(bounds.Dx()) - 0.5 y := (float64(point.Y) + 0.5) / float64(bounds.Dy()) - 0.5 return math.Hypot(x, y) <= 0.5 }