muffin v7.5.5

Auspex/Auspex/AxMultiStopLinearGradient.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Numerics;
+using Auspex.Rendering.Direct3D;
+
+namespace Auspex;
+
+public readonly struct AxMultiStopLinearGradient : IPctGradient
+{
+	private readonly Vector3 _start;
+
+	private readonly Vector3 _axis;
+
+	private readonly float _invLenSq;
+
+	private readonly float[] _positions;
+
+	private readonly Vector4[] _colors;
+
+	public AxMultiStopLinearGradient(Vector3 start, Vector3 end, params AxGradientStop[] stops)
+	{
+		_start = start;
+		_axis = end - start;
+		_invLenSq = 1f / Vector3.Dot(_axis, _axis);
+		(_positions, _colors) = ParseStops(stops);
+	}
+
+	public uint ColorAt(Vector3 point)
+	{
+		return SampleStops(Math.Clamp(Vector3.Dot(point - _start, _axis) * _invLenSq, 0f, 1f), _positions, _colors).ToUint();
+	}
+
+	internal static (float[] Positions, Vector4[] Colors) ParseStops(AxGradientStop[] stops)
+	{
+		AxGradientStop[] array = (AxGradientStop[])stops.Clone();
+		Array.Sort(array, (AxGradientStop a, AxGradientStop b) => a.Position.CompareTo(b.Position));
+		float[] array2 = new float[array.Length];
+		Vector4[] array3 = new Vector4[array.Length];
+		for (int num = 0; num < array.Length; num++)
+		{
+			array2[num] = array[num].Position;
+			array3[num] = array[num].Color.ToVector4();
+		}
+		return (Positions: array2, Colors: array3);
+	}
+
+	internal static Vector4 SampleStops(float t, float[] positions, Vector4[] colors)
+	{
+		if (colors.Length == 0)
+		{
+			return Vector4.Zero;
+		}
+		if (t <= positions[0])
+		{
+			return colors[0];
+		}
+		if (t >= positions[^1])
+		{
+			return colors[^1];
+		}
+		for (int i = 0; i < positions.Length - 1; i++)
+		{
+			if (t <= positions[i + 1])
+			{
+				float amount = (t - positions[i]) / (positions[i + 1] - positions[i]);
+				return Vector4.Lerp(colors[i], colors[i + 1], amount);
+			}
+		}
+		return colors[^1];
+	}
+}