AssetRipper_AssetRipper/Source/AssetRipper.Export.Modules.Textures/TerrainHeatmap.cs

using AssetRipper.Assets.Generics;
using AssetRipper.Numerics;
using AssetRipper.SourceGenerated.Classes.ClassID_156;
using AssetRipper.TextureDecoder.Rgb.Formats;

namespace AssetRipper.Export.Modules.Textures;

public static class TerrainHeatmap
{
	public static DirectBitmap GetBitmap(ITerrainData terrain)
	{
		DirectBitmap bitmap = new DirectBitmap<ColorRGBA<byte>, byte>(
			Math.Max(terrain.Heightmap.Width, terrain.Heightmap.Resolution),
			Math.Max(terrain.Heightmap.Height, terrain.Heightmap.Resolution),
			1,
			GetRGBA32Data(terrain));
		bitmap.FlipY();
		return bitmap;
	}

	public static byte[] GetRGBA32Data(ITerrainData terrain)
	{
		AssetList<short> heights = terrain.Heightmap.Heights;
		byte[] result = new byte[heights.Count * 4];
		for (int y = 0; y < heights.Count; y++)
		{
			Color32 color = (Color32)ConvertToColor((float)heights[y] / short.MaxValue);
			result[4 * y] = color.R;
			result[4 * y + 1] = color.G;
			result[4 * y + 2] = color.B;
			result[4 * y + 3] = byte.MaxValue; //small optimization
		}
		return result;
	}

	private static ColorFloat ConvertToColor(float value)
	{
		if (value <= 0f)
		{
			return zero;
		}
		else if (value < q1point)
		{
			return Average(zero, 0f, q1, q1point, value);
		}
		else if (value < q2point)
		{
			return Average(q1, q1point, q2, q2point, value);
		}
		else if (value < q3point)
		{
			return Average(q2, q2point, q3, q3point, value);
		}
		else if (value < 1f)
		{
			return Average(q3, q3point, one, 1f, value);
		}
		else
		{
			return one;
		}
	}

	private static float Normalize(float min, float max, float value)
	{
		if (value <= min)
		{
			return 0f;
		}
		else if (value >= max)
		{
			return 1f;
		}
		else
		{
			return (value - min) / (max - min);
		}
	}

	private static ColorFloat Average(ColorFloat minColor, float min, ColorFloat maxColor, float max, float value)
	{
		float normalized = Normalize(min, max, value);
		return (1 - normalized) * minColor + normalized * maxColor;
	}

	private static readonly ColorFloat zero = new(0, 0, 0.4f, 1);
	private static readonly ColorFloat q1 = new(0, 0, 1, 1);
	private static readonly ColorFloat q2 = new(0, 1, 0, 1);
	private static readonly ColorFloat q3 = new(1, 0, 0, 1);
	private static readonly ColorFloat one = ColorFloat.White;

	private const float q1point = 0.15f;
	private const float q2point = 0.3f;
	private const float q3point = 0.6f;
}