MoonWorks/src/Graphics/State/RasterizerState.cs

using SDL2_gpuCS;

namespace MoonWorks.Graphics;

/// <summary>
/// Specifies how the rasterizer should be configured for a graphics pipeline.
/// </summary>
public struct RasterizerState
{
	/// <summary>
	/// Specifies whether front faces, back faces, none, or both should be culled.
	/// </summary>
	public CullMode CullMode;

	/// <summary>
	/// Specifies maximum depth bias of a fragment. Only applies if depth biasing is enabled.
	/// </summary>
	public float DepthBiasClamp;

	/// <summary>
	/// The constant depth value added to each fragment. Only applies if depth biasing is enabled.
	/// </summary>
	public float DepthBiasConstantFactor;

	/// <summary>
	/// Specifies whether depth biasing is enabled. Only applies if depth biasing is enabled.
	/// </summary>
	public bool DepthBiasEnable;

	/// <summary>
	/// Factor applied to a fragment's slope in depth bias calculations. Only applies if depth biasing is enabled.
	/// </summary>
	public float DepthBiasSlopeFactor;

	/// <summary>
	/// Specifies how triangles should be drawn.
	/// </summary>
	public FillMode FillMode;

	/// <summary>
	/// Specifies which triangle winding order is designated as front-facing.
	/// </summary>
	public FrontFace FrontFace;

	public static readonly RasterizerState CW_CullFront = new RasterizerState
	{
		CullMode = CullMode.Front,
		FrontFace = FrontFace.Clockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CW_CullBack = new RasterizerState
	{
		CullMode = CullMode.Back,
		FrontFace = FrontFace.Clockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CW_CullNone = new RasterizerState
	{
		CullMode = CullMode.None,
		FrontFace = FrontFace.Clockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CW_Wireframe = new RasterizerState
	{
		CullMode = CullMode.None,
		FrontFace = FrontFace.Clockwise,
		FillMode = FillMode.Line,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CCW_CullFront = new RasterizerState
	{
		CullMode = CullMode.Front,
		FrontFace = FrontFace.CounterClockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CCW_CullBack = new RasterizerState
	{
		CullMode = CullMode.Back,
		FrontFace = FrontFace.CounterClockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CCW_CullNone = new RasterizerState
	{
		CullMode = CullMode.None,
		FrontFace = FrontFace.CounterClockwise,
		FillMode = FillMode.Fill,
		DepthBiasEnable = false
	};

	public static readonly RasterizerState CCW_Wireframe = new RasterizerState
	{
		CullMode = CullMode.None,
		FrontFace = FrontFace.CounterClockwise,
		FillMode = FillMode.Line,
		DepthBiasEnable = false
	};

	public SDL_Gpu.RasterizerState ToSDL()
	{
		return new SDL_Gpu.RasterizerState
		{
			CullMode = (SDL_Gpu.CullMode) CullMode,
			DepthBiasClamp = DepthBiasClamp,
			DepthBiasConstantFactor = DepthBiasConstantFactor,
			DepthBiasEnable = Conversions.BoolToInt(DepthBiasEnable),
			DepthBiasSlopeFactor = DepthBiasSlopeFactor,
			FillMode = (SDL_Gpu.FillMode) FillMode,
			FrontFace = (SDL_Gpu.FrontFace) FrontFace
		};
	}
}