// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence. // See the LICENCE file in the repository root for full licence text. using System; using System.Collections.Generic; using System.Linq; using osu.Framework.Graphics; using osu.Framework.Graphics.Shapes; using osu.Framework.Utils; using osuTK; namespace osu.Game.Screens.Edit.Compose.Components { public abstract partial class LinedPositionSnapGrid : PositionSnapGrid { protected void GenerateGridLines(Vector2 step, Vector2 drawSize) { if (Precision.AlmostEquals(step, Vector2.Zero)) return; int index = 0; // Make lines the same width independent of display resolution. float lineWidth = DrawWidth / ScreenSpaceDrawQuad.Width; float rotation = MathHelper.RadiansToDegrees(MathF.Atan2(step.Y, step.X)); List<Box> generatedLines = new List<Box>(); while (true) { Vector2 currentPosition = StartPosition.Value + index * step; index++; if (!lineDefinitelyIntersectsBox(currentPosition, step.PerpendicularLeft, drawSize, out var p1, out var p2)) { if (!isMovingTowardsBox(currentPosition, step, drawSize)) break; continue; } var gridLine = new Box { Colour = Colour4.White, Alpha = 0.1f, Origin = Anchor.Centre, RelativeSizeAxes = Axes.None, Width = lineWidth, Height = Vector2.Distance(p1, p2), Position = (p1 + p2) / 2, Rotation = rotation, }; generatedLines.Add(gridLine); } if (generatedLines.Count == 0) return; generatedLines.First().Alpha = 0.2f; AddRangeInternal(generatedLines); } private bool isMovingTowardsBox(Vector2 currentPosition, Vector2 step, Vector2 box) { return (currentPosition + step).LengthSquared < currentPosition.LengthSquared || (currentPosition + step - box).LengthSquared < (currentPosition - box).LengthSquared; } /// <summary> /// Determines if the line starting at <paramref name="lineStart"/> and going in the direction of <paramref name="lineDir"/> /// definitely intersects the box on (0, 0) with the given width and height and returns the intersection points if it does. /// </summary> /// <param name="lineStart">The start point of the line.</param> /// <param name="lineDir">The direction of the line.</param> /// <param name="box">The width and height of the box.</param> /// <param name="p1">The first intersection point.</param> /// <param name="p2">The second intersection point.</param> /// <returns>Whether the line definitely intersects the box.</returns> private bool lineDefinitelyIntersectsBox(Vector2 lineStart, Vector2 lineDir, Vector2 box, out Vector2 p1, out Vector2 p2) { p1 = Vector2.Zero; p2 = Vector2.Zero; if (Precision.AlmostEquals(lineDir.X, 0)) { // If the line is vertical, we only need to check if the X coordinate of the line is within the box. if (!Precision.DefinitelyBigger(lineStart.X, 0) || !Precision.DefinitelyBigger(box.X, lineStart.X)) return false; p1 = new Vector2(lineStart.X, 0); p2 = new Vector2(lineStart.X, box.Y); return true; } if (Precision.AlmostEquals(lineDir.Y, 0)) { // If the line is horizontal, we only need to check if the Y coordinate of the line is within the box. if (!Precision.DefinitelyBigger(lineStart.Y, 0) || !Precision.DefinitelyBigger(box.Y, lineStart.Y)) return false; p1 = new Vector2(0, lineStart.Y); p2 = new Vector2(box.X, lineStart.Y); return true; } float m = lineDir.Y / lineDir.X; float mInv = lineDir.X / lineDir.Y; // Use this to improve numerical stability if X is close to zero. float b = lineStart.Y - m * lineStart.X; // Calculate intersection points with the sides of the box. var p = new List<Vector2>(4); if (0 <= b && b <= box.Y) p.Add(new Vector2(0, b)); if (0 <= (box.Y - b) * mInv && (box.Y - b) * mInv <= box.X) p.Add(new Vector2((box.Y - b) * mInv, box.Y)); if (0 <= m * box.X + b && m * box.X + b <= box.Y) p.Add(new Vector2(box.X, m * box.X + b)); if (0 <= -b * mInv && -b * mInv <= box.X) p.Add(new Vector2(-b * mInv, 0)); switch (p.Count) { case 4: // If there are 4 intersection points, the line is a diagonal of the box. if (m > 0) { p1 = Vector2.Zero; p2 = box; } else { p1 = new Vector2(0, box.Y); p2 = new Vector2(box.X, 0); } break; case 3: // If there are 3 intersection points, the line goes through a corner of the box. if (p[0] == p[1]) { p1 = p[0]; p2 = p[2]; } else { p1 = p[0]; p2 = p[1]; } break; case 2: p1 = p[0]; p2 = p[1]; break; } return !Precision.AlmostEquals(p1, p2); } } }