70 lines
2.4 KiB
C#
70 lines
2.4 KiB
C#
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using Godot;
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namespace Theriapolis.GodotHost.Rendering;
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/// <summary>
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/// Camera2D with mouse-wheel zoom and middle/right-button click-drag pan.
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/// Zoom is centered on the cursor so zooming feels natural. Bounds:
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/// the zoom factor is clamped between MinZoom (everything fits) and
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/// MaxZoom (1 tile fills the screen).
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/// </summary>
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public partial class PanZoomCamera : Camera2D
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{
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[Export] public float MinZoom { get; set; } = 0.04f;
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[Export] public float MaxZoom { get; set; } = 4.0f;
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[Export] public float ZoomStep { get; set; } = 1.15f;
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private bool _dragging;
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private Vector2 _dragStartCursor;
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private Vector2 _dragStartCameraPos;
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public override void _UnhandledInput(InputEvent @event)
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{
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switch (@event)
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{
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case InputEventMouseButton mb when mb.Pressed:
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HandleMouseButtonPressed(mb);
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break;
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case InputEventMouseButton mb when !mb.Pressed:
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if (mb.ButtonIndex is MouseButton.Middle or MouseButton.Right)
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_dragging = false;
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break;
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case InputEventMouseMotion mm when _dragging:
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Position = _dragStartCameraPos
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+ (_dragStartCursor - mm.Position) / Zoom;
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break;
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}
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}
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private void HandleMouseButtonPressed(InputEventMouseButton mb)
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{
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switch (mb.ButtonIndex)
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{
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case MouseButton.WheelUp:
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ApplyZoom(ZoomStep, mb.Position);
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break;
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case MouseButton.WheelDown:
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ApplyZoom(1f / ZoomStep, mb.Position);
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break;
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case MouseButton.Middle:
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case MouseButton.Right:
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_dragging = true;
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_dragStartCursor = mb.Position;
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_dragStartCameraPos = Position;
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break;
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}
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}
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private void ApplyZoom(float factor, Vector2 cursorScreen)
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{
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float newZoom = Mathf.Clamp(Zoom.X * factor, MinZoom, MaxZoom);
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if (Mathf.IsEqualApprox(newZoom, Zoom.X)) return;
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// Zoom toward the cursor: keep the world point under the cursor fixed.
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Vector2 worldBefore = GetCanvasTransform().AffineInverse() * cursorScreen;
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Zoom = new Vector2(newZoom, newZoom);
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Vector2 worldAfter = GetCanvasTransform().AffineInverse() * cursorScreen;
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Position += worldBefore - worldAfter;
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}
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}
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