// Copyright Epic Games, Inc. All Rights Reserved.

/*================================================================================================
	SubstrateDefinitions.ush: used in ray tracing shaders and C++ code to define common constants
	!!! Changing this file requires recompilation of the engine !!!
=================================================================================================*/

#pragma once

// Change this to force recompilation of all Substrate dependent shaders (use https://www.random.org/cgi-bin/randbyte?nbytes=4&format=h)
#define SUBSTRATE_SHADER_VERSION 0XA577A11B

// BSDF offsets are packed into 32bits, each entry using SUBSTRATE_BSDF_OFFSET_BIT_COUNT bits
#define SUBSTRATE_MAX_BSDF_COUNT_FOR_BDSFOFFSET			8u
#define SUBSTRATE_BSDF_OFFSET_BIT_COUNT					4u
#define SUBSTRATE_BSDF_OFFSET_BIT_MASK					0xF

// We can only ever use SUBSTRATE_MAX_BSDF_COUNT_FOR_BDSFOFFSET BSDFs for Lumen, so we use that as a global BSDF count limit today.
#define SUBSTRATE_MAX_BSDF_COUNT						SUBSTRATE_MAX_BSDF_COUNT_FOR_BDSFOFFSET
#define SUBSTRATE_MAX_OPERATOR_COUNT					15

// It this is changed, STATE_BIT_COUNT_SHAREDLOCALBASESID and HEADER_BIT_COUNT_SHAREDLOCALBASES_COUNT also needs to be updated
#define SUBSTRATE_MAX_SHAREDLOCALBASES_REGISTERS		4

#define SUBSTRATE_PACKED_SHAREDLOCALBASIS_STRIDE_BYTES	4

// As of today, a fully simplified material is a slab with all features allowed. It can thus be complex if anisotropy is enabled and in this case eats up to 32bytes.
// SUBSTRATE_TODO: fully simplified should remove all features but fuzz maybe. 
#define SUBSTRATE_FULLY_SIMPLIFIED_NUM_UINTS			(32/4)

#define SUBSTRATE_BSDF_TYPE_SLAB						0
#define SUBSTRATE_BSDF_TYPE_VOLUMETRICFOGCLOUD			1
#define SUBSTRATE_BSDF_TYPE_UNLIT						2
#define SUBSTRATE_BSDF_TYPE_HAIR						3
#define SUBSTRATE_BSDF_TYPE_SINGLELAYERWATER			4
#define SUBSTRATE_BSDF_TYPE_EYE							5
// When more than 7 BSDF must exists, please update STATE_BIT_COUNT_BSDF and FSubstrateClassification.ShadingModels packing in Substrate.ush

// The size of Substrate material classification tiles on screen
#define SUBSTRATE_TILE_SIZE								8
#define SUBSTRATE_TILE_SIZE_DIV_AS_SHIFT				3

// The default thickness of a layer is considered to be 0.01 centimeter = 0.1 millimeter
#define SUBSTRATE_LAYER_DEFAULT_THICKNESS_CM			0.01f

// Min Fuzz Roughness to avoid numerical issue
#define SUBSTRATE_MIN_FUZZ_ROUGHNESS					0.02f

#define SUBSTRATE_BASE_PASS_MRT_OUTPUT_COUNT			3

#define SUBSTRATE_SSS_DATA_UINT_COUNT					2

#define SUBSTRATE_OPERATOR_WEIGHT						0
#define SUBSTRATE_OPERATOR_VERTICAL						1
#define SUBSTRATE_OPERATOR_HORIZONTAL					2
#define SUBSTRATE_OPERATOR_ADD							3
#define SUBSTRATE_OPERATOR_BSDF							4
#define SUBSTRATE_OPERATOR_BSDF_LEGACY					5

// This must map directly to ESubstrateTileMaterialType
#define SUBSTRATE_TILE_TYPE_SIMPLE						0
#define SUBSTRATE_TILE_TYPE_SINGLE						1
#define SUBSTRATE_TILE_TYPE_COMPLEX						2
#define SUBSTRATE_TILE_TYPE_COMPLEX_SPECIAL				3
#define SUBSTRATE_TILE_TYPE_ROUGH_REFRACT				4
#define SUBSTRATE_TILE_TYPE_ROUGH_REFRACT_SSS_WITHOUT	5
#define SUBSTRATE_TILE_TYPE_DECAL_SIMPLE				6
#define SUBSTRATE_TILE_TYPE_DECAL_SINGLE				7
#define SUBSTRATE_TILE_TYPE_DECAL_COMPLEX				8
#define SUBSTRATE_TILE_TYPE_COUNT						9

// sizeof(FRHIDrawIndirectParameters) = 4 uints = 16 bytes
#define GetSubstrateTileTypeDrawIndirectArgOffset_Byte(x)  (x * 16)
#define GetSubstrateTileTypeDrawIndirectArgOffset_DWord(x) (x * 4)

// sizeof(FRHIDispatchIndirectParameters) can vary per-platform
#ifdef __cplusplus
	#define GetSubstrateTileTypeDispatchIndirectArgOffset_Byte(x)  (x * sizeof(FRHIDispatchIndirectParameters))
	#define GetSubstrateTileTypeDispatchIndirectArgOffset_DWord(x) (x * sizeof(FRHIDispatchIndirectParameters) / sizeof(uint32))
#else
	#define GetSubstrateTileTypeDispatchIndirectArgOffset_Byte(x)  (x * DISPATCH_INDIRECT_UINT_COUNT * 4)
	#define GetSubstrateTileTypeDispatchIndirectArgOffset_DWord(x) (x * DISPATCH_INDIRECT_UINT_COUNT)
#endif