FLIP fluid simulation example

70_FLIPFluids/CMakeLists.txt

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+include(common RESULT_VARIABLE RES)
+if(NOT RES)
+	message(FATAL_ERROR "common.cmake not found. Should be in {repo_root}/cmake directory")
+endif()
+
+nbl_create_executable_project("" "" "" "" "${NBL_EXECUTABLE_PROJECT_CREATION_PCH_TARGET}")
+
+if(NBL_EMBED_BUILTIN_RESOURCES)
+	set(_BR_TARGET_ ${EXECUTABLE_NAME}_builtinResourceData)
+	set(RESOURCE_DIR "app_resources")
+
+	get_filename_component(_SEARCH_DIRECTORIES_ "${CMAKE_CURRENT_SOURCE_DIR}" ABSOLUTE)
+	get_filename_component(_OUTPUT_DIRECTORY_SOURCE_ "${CMAKE_CURRENT_BINARY_DIR}/src" ABSOLUTE)
+	get_filename_component(_OUTPUT_DIRECTORY_HEADER_ "${CMAKE_CURRENT_BINARY_DIR}/include" ABSOLUTE)
+
+    file(GLOB_RECURSE BUILTIN_RESOURCE_FILES RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}/${RESOURCE_DIR}" CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/${RESOURCE_DIR}/*")
+    foreach(RES_FILE ${BUILTIN_RESOURCE_FILES})
+      LIST_BUILTIN_RESOURCE(RESOURCES_TO_EMBED "${RES_FILE}")
+    endforeach()
+
+	ADD_CUSTOM_BUILTIN_RESOURCES(${_BR_TARGET_} RESOURCES_TO_EMBED "${_SEARCH_DIRECTORIES_}" "${RESOURCE_DIR}" "nbl::this_example::builtin" "${_OUTPUT_DIRECTORY_HEADER_}" "${_OUTPUT_DIRECTORY_SOURCE_}")
+
+	LINK_BUILTIN_RESOURCES_TO_TARGET(${EXECUTABLE_NAME} ${_BR_TARGET_})
+endif()

70_FLIPFluids/README.md

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+https://github.com/user-attachments/assets/fc8bfac9-c8fb-49f1-87d6-251aae015945

70_FLIPFluids/app_resources/cellUtils.hlsl

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+#ifndef _FLIP_EXAMPLE_CELL_UTILS_HLSL
+#define _FLIP_EXAMPLE_CELL_UTILS_HLSL
+
+#ifdef __HLSL_VERSION
+static const uint CM_SOLID = 0;
+static const uint CM_FLUID = 1;
+static const uint CM_AIR = 2;
+
+static const uint CellMatMask       = 0x00000003u;
+static const uint CellMatMaskShift  = 0;
+static const uint XPrevMatMask      = 0x0000000cu;
+static const uint XPrevMatMaskShift = 2;
+static const uint XNextMatMask      = 0x00000030u;
+static const uint XNextMatMaskShift = 4;
+static const uint YPrevMatMask      = 0x000000c0u;
+static const uint YPrevMatMaskShift = 6;
+static const uint YNextMatMask      = 0x00000300u;
+static const uint YNextMatMaskShift = 8;
+static const uint ZPrevMatMask      = 0x00000c00u;
+static const uint ZPrevMatMaskShift = 10;
+static const uint ZNextMatMask      = 0x00003000u;
+static const uint ZNextMatMaskShift = 12;
+
+inline void setCellMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~CellMatMask) | ((cellMaterial << CellMatMaskShift) & CellMatMask);
+}
+inline uint getCellMaterial(uint cellMaterials)
+{
+    return (cellMaterials & CellMatMask) >> CellMatMaskShift;
+}
+inline void setXPrevMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~XPrevMatMask) | ((cellMaterial << XPrevMatMaskShift) & XPrevMatMask);
+}
+inline uint getXPrevMaterial(uint cellMaterials)
+{
+    return (cellMaterials & XPrevMatMask) >> XPrevMatMaskShift;
+}
+inline void setXNextMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~XNextMatMask) | ((cellMaterial << XNextMatMaskShift) & XNextMatMask);
+}
+inline uint getXNextMaterial(uint cellMaterials)
+{
+    return (cellMaterials & XNextMatMask) >> XNextMatMaskShift;
+}
+inline void setYPrevMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~YPrevMatMask) | ((cellMaterial << YPrevMatMaskShift) & YPrevMatMask);
+}
+inline uint getYPrevMaterial(uint cellMaterials)
+{
+    return (cellMaterials & YPrevMatMask) >> YPrevMatMaskShift;
+}
+inline void setYNextMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~YNextMatMask) | ((cellMaterial << YNextMatMaskShift) & YNextMatMask);
+}
+inline uint getYNextMaterial(uint cellMaterials)
+{
+    return (cellMaterials & YNextMatMask) >> YNextMatMaskShift;
+}
+inline void setZPrevMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~ZPrevMatMask) | ((cellMaterial << ZPrevMatMaskShift) & ZPrevMatMask);
+}
+inline uint getZPrevMaterial(uint cellMaterials)
+{
+    return (cellMaterials & ZPrevMatMask) >> ZPrevMatMaskShift;
+}
+inline void setZNextMaterial(inout uint cellMaterials, uint cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~ZNextMatMask) | ((cellMaterial << ZNextMatMaskShift) & ZNextMatMask);
+}
+inline uint getZNextMaterial(uint cellMaterials)
+{
+    return (cellMaterials & ZNextMatMask) >> ZNextMatMaskShift;
+}
+
+
+inline void setCellMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~CellMatMask) | ((cellMaterial << CellMatMaskShift) & CellMatMask);
+}
+inline uint3 getCellMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & CellMatMask) >> CellMatMaskShift;
+}
+inline void setXPrevMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~XPrevMatMask) | ((cellMaterial << XPrevMatMaskShift) & XPrevMatMask);
+}
+inline uint3 getXPrevMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & XPrevMatMask) >> XPrevMatMaskShift;
+}
+inline void setXNextMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~XNextMatMask) | ((cellMaterial << XNextMatMaskShift) & XNextMatMask);
+}
+inline uint3 getXNextMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & XNextMatMask) >> XNextMatMaskShift;
+}
+inline void setYPrevMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~YPrevMatMask) | ((cellMaterial << YPrevMatMaskShift) & YPrevMatMask);
+}
+inline uint3 getYPrevMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & YPrevMatMask) >> YPrevMatMaskShift;
+}
+inline void setYNextMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~YNextMatMask) | ((cellMaterial << YNextMatMaskShift) & YNextMatMask);
+}
+inline uint3 getYNextMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & YNextMatMask) >> YNextMatMaskShift;
+}
+inline void setZPrevMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~ZPrevMatMask) | ((cellMaterial << ZPrevMatMaskShift) & ZPrevMatMask);
+}
+inline uint3 getZPrevMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & ZPrevMatMask) >> ZPrevMatMaskShift;
+}
+inline void setZNextMaterial(inout uint3 cellMaterials, uint3 cellMaterial)
+{
+    cellMaterials = (cellMaterials & ~ZNextMatMask) | ((cellMaterial << ZNextMatMaskShift) & ZNextMatMask);
+}
+inline uint3 getZNextMaterial(uint3 cellMaterials)
+{
+    return (cellMaterials & ZNextMatMask) >> ZNextMatMaskShift;
+}
+
+
+inline bool isSolidCell(uint cellMaterial)
+{
+    return cellMaterial == CM_SOLID;
+}
+inline bool isFluidCell(uint cellMaterial)
+{
+    return cellMaterial == CM_FLUID;
+}
+inline bool isAirCell(uint cellMaterial)
+{
+    return cellMaterial == CM_AIR;
+}
+
+inline bool3 isSolidCell(uint3 cellMaterial)
+{
+    return cellMaterial == (uint3)CM_SOLID;
+}
+inline bool3 isFluidCell(uint3 cellMaterial)
+{
+    return cellMaterial == (uint3)CM_FLUID;
+}
+inline bool3 isAirCell(uint3 cellMaterial)
+{
+    return cellMaterial == (uint3)CM_AIR;
+}
+
+void enforceBoundaryCondition(inout float3 velocity, uint cellMaterial)
+{
+    bool3 is_solid_cell =
+        or((bool3)isSolidCell(getCellMaterial(cellMaterial)),
+        bool3(isSolidCell(getXPrevMaterial(cellMaterial)), isSolidCell(getYPrevMaterial(cellMaterial)), isSolidCell(getZPrevMaterial(cellMaterial))));
+    velocity = select(is_solid_cell, 0.0f, velocity);
+}
+
+// handling solid obstacles
+inline bool3 isSolidCell(float3 position)
+{
+    // no obstacles for now, in cuboid sim area
+    return false;
+}
+
+#endif
+#endif

70_FLIPFluids/app_resources/common.hlsl

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+#ifndef _FLIP_EXAMPLE_COMMON_HLSL
+#define _FLIP_EXAMPLE_COMMON_HLSL
+
+#include "nbl/builtin/hlsl/cpp_compat.hlsl"
+
+#define NUM_THREADS 128
+
+NBL_CONSTEXPR uint32_t WorkgroupSize = NUM_THREADS;
+NBL_CONSTEXPR float ratioFLIPPIC = 0.95;
+NBL_CONSTEXPR float deltaTime = 1.0f / 60.0f;
+NBL_CONSTEXPR float gravity = 15.0f;
+
+#ifdef __HLSL_VERSION
+
+static const float FLT_MIN = 1.175494351e-38;
+static const float FLT_MAX = 3.402823466e+38;
+
+struct Particle
+{
+    float4 position;
+    float4 velocity;
+
+    uint id;
+    uint pad[3];
+};
+
+struct SMVPParams
+{
+    float4 camPos;
+
+	float4x4 MVP;
+	float4x4 M;
+	float4x4 V;
+    float4x4 P;
+};
+#endif
+
+#endif

70_FLIPFluids/app_resources/compute/advectParticles.comp.hlsl

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+#include "../common.hlsl"
+#include "../gridSampling.hlsl"
+#include "../descriptor_bindings.hlsl"
+
+[[vk::binding(b_apGridData, s_ap)]]
+cbuffer GridData
+{
+    SGridData gridData;
+};
+
+[[vk::binding(b_apPBuffer, s_ap)]] RWStructuredBuffer<Particle> particleBuffer;
+[[vk::binding(b_apVelFieldBuffer, s_ap)]] Texture3D<float4> velocityFieldBuffer;
+[[vk::binding(b_apVelSampler, s_ap)]] SamplerState velocityFieldSampler;
+
+// delta time push constant?
+
+[numthreads(WorkgroupSize, 1, 1)]
+void main(uint32_t3 ID : SV_DispatchThreadID)
+{
+    uint32_t pid = ID.x;
+
+    Particle p = particleBuffer[pid];
+
+    // use RK4
+    float3 k1 = sampleVelocityAt(p.position.xyz, velocityFieldBuffer, velocityFieldSampler, gridData);
+    float3 k2 = sampleVelocityAt(p.position.xyz + k1 * 0.5f * deltaTime, velocityFieldBuffer, velocityFieldSampler, gridData);
+    float3 k3 = sampleVelocityAt(p.position.xyz + k2 * 0.5f * deltaTime, velocityFieldBuffer, velocityFieldSampler, gridData);
+    float3 k4 = sampleVelocityAt(p.position.xyz + k3 * deltaTime, velocityFieldBuffer, velocityFieldSampler, gridData);
+    float3 velocity = (k1 + 2.0f * k2 + 2.0f * k3 + k4) / 6.0f;
+
+    p.position.xyz += velocity * deltaTime;
+
+    p.position = clampPosition(p.position, gridData.worldMin, gridData.worldMax);
+
+    particleBuffer[pid] = p;
+}

70_FLIPFluids/app_resources/compute/applyBodyForces.comp.hlsl

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+#include "../common.hlsl"
+#include "../gridUtils.hlsl"
+#include "../cellUtils.hlsl"
+#include "../descriptor_bindings.hlsl"
+
+[[vk::binding(b_abfGridData, s_abf)]]
+cbuffer GridData
+{
+    SGridData gridData;
+};
+
+[[vk::binding(b_abfVelFieldBuffer, s_abf)]] RWTexture3D<float4> velocityFieldBuffer;
+[[vk::binding(b_abfCMBuffer, s_abf)]] RWStructuredBuffer<uint> cellMaterialBuffer;
+
+[numthreads(WorkgroupSize, 1, 1)]
+void main(uint32_t3 ID : SV_DispatchThreadID)
+{
+    // only gravity for now
+    uint c_id = ID.x;
+    int3 cIdx = flatIdxToCellIdx(c_id, gridData.gridSize);
+
+    float3 velocity = velocityFieldBuffer[cIdx].xyz;
+    velocity += float3(0, -1, 0) * gravity * deltaTime;
+
+    enforceBoundaryCondition(velocity, cellMaterialBuffer[c_id]);
+
+    velocityFieldBuffer[cIdx].xyz = velocity;
+}