AssetRipper_AssetRipper/Source/AssetRipper.Export.Modules.Shader/ConstantBuffers/Variable.cs

using AssetRipper.Export.Modules.Shaders.ShaderBlob.Parameters;
using AssetRipper.SourceGenerated.Extensions.Enums.Shader;
using AssetRipper.SourceGenerated.Extensions.Enums.Shader.GpuProgramType;

namespace AssetRipper.Export.Modules.Shaders.ConstantBuffers;

internal class Variable
{
	private Variable(string name, Types.ShaderType shaderType)
	{
		Name = name;
		ShaderType = shaderType;
	}

	public Variable(MatrixParameter param, ShaderGpuProgramType programType)
	{
		ShaderType = new Types.ShaderType(param, programType);
		Name = param.Name ?? throw new Exception("Variable name cannot be null");
		NameIndex = param.NameIndex;
		Index = param.Index;
		ArraySize = param.ArraySize;
		Length = (uint)(param.RowCount * param.ColumnCount * 4);
	}

	public Variable(VectorParameter param, ShaderGpuProgramType programType)
	{
		ShaderType = new Types.ShaderType(param, programType);
		Name = param.Name ?? throw new Exception("Variable name cannot be null");
		NameIndex = param.NameIndex;
		Index = param.Index;
		ArraySize = param.ArraySize;
		Length = (uint)(param.Dim * 4);
	}

	public Variable(StructParameter param, ShaderGpuProgramType programType)
	{
		ShaderType = new Types.ShaderType(param, programType);
		Name = param.Name ?? throw new Exception("Variable name cannot be null");
		NameIndex = param.NameIndex;
		Index = param.Index;
		ArraySize = param.ArraySize;
	}

	public static Variable CreateDummyVariable(string name, int index, int sizeToAdd, ShaderGpuProgramType programType)
	{
		if (sizeToAdd % 4 != 0 || sizeToAdd <= 0)
		{
			throw new Exception($"Invalid dummy variable size {sizeToAdd}");
		}

		//Constant Buffer indices have a stride of 16 bytes
		int alignIndex = index % 16;
		if (alignIndex != 0)
		{
			index += 16 - alignIndex;
			sizeToAdd -= 16 - alignIndex;
		}
		sizeToAdd -= sizeToAdd % 16;

		VectorParameter param = new VectorParameter(name, ShaderParamType.Float, index, sizeToAdd / 16, 4);
		Variable variable = new Variable(name, new Types.ShaderType(param, programType));
		variable.NameIndex = -1;
		variable.Index = index;
		variable.ArraySize = param.ArraySize;
		variable.Type = ShaderParamType.Int;
		variable.Length = (uint)sizeToAdd;
		return variable;
	}

	public static Variable CreateResourceBindVariable(ShaderGpuProgramType programType)
	{
		string name = "$Element";
		VectorParameter param = new VectorParameter(name, ShaderParamType.UInt, 0, 1);
		Variable variable = new Variable(name, new Types.ShaderType(param, programType));
		variable.NameIndex = -1;
		variable.Index = 0;
		variable.ArraySize = param.ArraySize;
		variable.Length = 4;
		variable.Type = ShaderParamType.UInt;
		return variable;
	}

	public Types.ShaderType ShaderType { get; private set; }
	public string Name { get; private set; }
	public int NameIndex { get; private set; }
	public int Index { get; private set; }
	public int ArraySize { get; private set; }
	public ShaderParamType Type { get; private set; }
	public uint Length { get; set; }

}