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gltfio: use tangent space mesh
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 - Fix missing attributes in TangentSpaceMesh
 - Fix missing reference in MikktspaceImpl.cpp
 - Add gltfio/src/extended to implement an alternate loader for
   primitives. This is largely based on the implementation in
   AssetLoader/ResourceLoader
 - Pull common methods between the two implementations into a
   utility namespace.
 - Switch gltf_viewer to use new gltf loader (extended loader).
 - Able to correctly produce flat shading from gltf that only have
   vertex positions and indices.
 - Able to run mikktspace to generate tangent spaces as per gltf
   spec

Fixes #7444; Fixes #6358
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@poweifeng
poweifeng committed Feb 13, 2024
1 parent 1308254 commit 3a23947
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Showing 20 changed files with 2,351 additions and 455 deletions.
2 changes: 1 addition & 1 deletion libs/geometry/include/geometry/TangentSpaceMesh.h
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Original file line number Diff line number Diff line change
Expand Up @@ -242,7 +242,7 @@ class TangentSpaceMesh {
* Destroy the mesh object
* @param mesh A pointer to a TangentSpaceMesh ready to be destroyed
*/
static void destroy(TangentSpaceMesh* mesh) noexcept;
static void destroy(TangentSpaceMesh* mesh) noexcept;

/**
* Move constructor
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79 changes: 61 additions & 18 deletions libs/geometry/src/MikktspaceImpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@

#include <math/mat3.h>
#include <math/norm.h>

#include <utils/Panic.h>

#include <meshoptimizer.h>
#include <mikktspace/mikktspace.h>
Expand Down Expand Up @@ -81,7 +81,7 @@ void MikktspaceImpl::setTSpaceBasic(SMikkTSpaceContext const* context, float con
// TODO: packTangentFrame actually changes the orientation of b.
quatf const quat = mat3f::packTangentFrame({t, b, n}, sizeof(int32_t));

auto output = wrapper->mOutputData;
auto& output = wrapper->mOutputData;
auto const& EMPTY_ELEMENT = wrapper->EMPTY_ELEMENT;

size_t const outputCurSize = output.size();
Expand All @@ -91,15 +91,15 @@ void MikktspaceImpl::setTSpaceBasic(SMikkTSpaceContext const* context, float con

uint8_t* cursor = output.data() + outputCurSize;

*((float3*) (cursor)) = pos;
*((float2*) (cursor + 12)) = uv;
*((quatf*) (cursor + 20)) = quat;
*((float3*) (cursor + POS_OFFSET)) = pos;
*((float2*) (cursor + UV_OFFSET)) = uv;
*((quatf*) (cursor + TBN_OFFSET)) = quat;

cursor += 36;
for (auto [attribArray, attribStride, attribSize]: wrapper->mInputAttribArrays) {
uint8_t const* input = pointerAdd(attribArray, vertInd, attribStride);
std::memcpy(cursor, input, attribSize);
cursor += attribSize;
cursor += BASE_OUTPUT_SIZE;
for (auto const& inputAttrib: wrapper->mInputAttribArrays) {
uint8_t const* input = pointerAdd(inputAttrib.data, vertInd, inputAttrib.stride);
memcpy(cursor, input, inputAttrib.size);
cursor += inputAttrib.size;
}
}

Expand All @@ -124,7 +124,12 @@ MikktspaceImpl::MikktspaceImpl(const TangentSpaceMeshInput* input) noexcept
for (auto attrib: input->getAuxAttributes()) {
size_t const attribSize =input->attributeSize(attrib);
mOutputElementSize += attribSize;
mInputAttribArrays.push_back({input->raw(attrib), input->stride(attrib), attribSize});
mInputAttribArrays.push_back({
.attrib = attrib,
.data = input->raw(attrib),
.stride = input->stride(attrib),
.size = attribSize,
});
}
mOutputData.reserve(mFaceCount * 3 * mOutputElementSize);

Expand Down Expand Up @@ -155,12 +160,12 @@ void MikktspaceImpl::run(TangentSpaceMeshOutput* output) noexcept {
genTangSpaceDefault(&context);

size_t oVertexCount = mOutputData.size() / mOutputElementSize;

std::vector<unsigned int> remap(oVertexCount);
std::vector<unsigned int> remap;
remap.resize(oVertexCount);
size_t vertexCount = meshopt_generateVertexRemap(remap.data(), NULL, remap.size(),
mOutputData.data(), oVertexCount, mOutputElementSize);

std::vector<IOVertex> newVertices(vertexCount);
std::vector<uint8_t> newVertices(vertexCount * mOutputElementSize);
meshopt_remapVertexBuffer((void*) newVertices.data(), mOutputData.data(), oVertexCount,
mOutputElementSize, remap.data());

Expand All @@ -171,10 +176,48 @@ void MikktspaceImpl::run(TangentSpaceMeshOutput* output) noexcept {
float2* outUVs = output->uvs().allocate(vertexCount);
quatf* outQuats = output->tspace().allocate(vertexCount);

for (size_t i = 0; i < vertexCount; ++i) {
outPositions[i] = newVertices[i].position;
outUVs[i] = newVertices[i].uv;
outQuats[i] = newVertices[i].tangentSpace;
uint8_t* const verts = newVertices.data();

std::vector<std::tuple<AttributeImpl, void*, size_t>> attributes;

for (auto const& inputAttrib: mInputAttribArrays) {
auto const attrib = inputAttrib.attrib;
switch(attrib) {
case AttributeImpl::UV1:
attributes.push_back(
{attrib, output->data<DATA_TYPE_UV1>(attrib).allocate(vertexCount),
inputAttrib.size});
break;
case AttributeImpl::COLORS:
attributes.push_back(
{attrib, output->data<DATA_TYPE_COLORS>(attrib).allocate(vertexCount),
inputAttrib.size});
break;
case AttributeImpl::JOINTS:
attributes.push_back(
{attrib, output->data<DATA_TYPE_JOINTS>(attrib).allocate(vertexCount),
inputAttrib.size});
break;
case AttributeImpl::WEIGHTS:
attributes.push_back(
{attrib, output->data<DATA_TYPE_WEIGHTS>(attrib).allocate(vertexCount),
inputAttrib.size});
break;
default:
PANIC_POSTCONDITION("Unexpected attribute=%d", (int) inputAttrib.attrib);
}
}

for (size_t i = 0, vi=0; i < vertexCount; ++i, vi+=mOutputElementSize) {
outPositions[i] = *((float3*) (verts + vi + POS_OFFSET));
outUVs[i] = *((float2*) (verts + vi + UV_OFFSET));
outQuats[i] = *((quatf*) (verts + vi + TBN_OFFSET));

uint8_t* cursor = verts + vi + BASE_OUTPUT_SIZE;
for (auto const [attrib, outdata, size] : attributes) {
memcpy((uint8_t*) outdata + (i * size), cursor, size);
cursor += size;
}
}

output->vertexCount = vertexCount;
Expand Down
18 changes: 16 additions & 2 deletions libs/geometry/src/MikktspaceImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,14 @@ class MikktspaceImpl {

private:
// sizeof(float3 + float2 + quatf) (pos, uv, tangent)
static constexpr size_t const BASE_OUTPUT_SIZE = 36;
static constexpr size_t const FLOAT3_SIZE = sizeof(float3);
static constexpr size_t const FLOAT2_SIZE = sizeof(float2);
static constexpr size_t const QUATF_SIZE = sizeof(quatf);

static constexpr size_t const POS_OFFSET = 0;
static constexpr size_t const UV_OFFSET = FLOAT3_SIZE;
static constexpr size_t const TBN_OFFSET = FLOAT3_SIZE + FLOAT2_SIZE;
static constexpr size_t const BASE_OUTPUT_SIZE = FLOAT3_SIZE + FLOAT2_SIZE + QUATF_SIZE;

static int getNumFaces(SMikkTSpaceContext const* context) noexcept;
static int getNumVerticesOfFace(SMikkTSpaceContext const* context, int const iFace) noexcept;
Expand All @@ -74,7 +81,14 @@ class MikktspaceImpl {
size_t const mUVStride;
uint8_t const* mTriangles;
bool mIsTriangle16;
std::vector<std::tuple<uint8_t const*, size_t, size_t>> mInputAttribArrays;

struct InputAttribute {
AttributeImpl attrib;
uint8_t const* data;
size_t stride;
size_t size;
};
std::vector<InputAttribute> mInputAttribArrays;

size_t mOutputElementSize;
std::vector<uint8_t> mOutputData;
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19 changes: 13 additions & 6 deletions libs/geometry/src/TangentSpaceMesh.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -503,6 +503,14 @@ void lengyelMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* o
output->triangles16.borrow(triangles16);
}

void auxImpl(TangentSpaceMeshInput::AttributeMap& attributeData, AttributeImpl attribute,
InData data, size_t stride) noexcept {
attributeData[attribute] = {
data,
stride ? stride : TangentSpaceMeshInput::attributeSize(attribute),
};
}

} // anonymous namespace

Builder::Builder() noexcept
Expand All @@ -527,27 +535,27 @@ Builder& Builder::vertexCount(size_t vertexCount) noexcept {
}

Builder& Builder::normals(float3 const* normals, size_t stride) noexcept {
mMesh->mInput->attributeData[AttributeImpl::NORMALS] = { normals, stride };
auxImpl(mMesh->mInput->attributeData, AttributeImpl::NORMALS, normals, stride);
return *this;
}

Builder& Builder::uvs(float2 const* uvs, size_t stride) noexcept {
mMesh->mInput->attributeData[AttributeImpl::UV0] = { uvs, stride };
auxImpl(mMesh->mInput->attributeData, AttributeImpl::UV0, uvs, stride);
return *this;
}

Builder& Builder::positions(float3 const* positions, size_t stride) noexcept {
mMesh->mInput->attributeData[AttributeImpl::POSITIONS] = { positions, stride };
auxImpl(mMesh->mInput->attributeData, AttributeImpl::POSITIONS, positions, stride);
return *this;
}

Builder& Builder::tangents(float4 const* tangents, size_t stride) noexcept {
mMesh->mInput->attributeData[AttributeImpl::TANGENTS] = { tangents, stride };
auxImpl(mMesh->mInput->attributeData, AttributeImpl::TANGENTS, tangents, stride);
return *this;
}

Builder& Builder::aux(AuxAttribute attribute, InData data, size_t stride) noexcept {
mMesh->mInput->attributeData[static_cast<AttributeImpl>(attribute)] = { data, stride };
auxImpl(mMesh->mInput->attributeData, static_cast<AttributeImpl>(attribute), data, stride);
return *this;
}

Expand Down Expand Up @@ -646,7 +654,6 @@ size_t TangentSpaceMesh::getVertexCount() const noexcept {

void TangentSpaceMesh::getPositions(float3* positions, size_t stride) const {
auto inPositions = mInput->positions();

ASSERT_PRECONDITION(inPositions, "Must provide input positions");
stride = stride ? stride : sizeof(decltype(*positions));
auto const& outPositions = mOutput->positions();
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6 changes: 3 additions & 3 deletions libs/geometry/src/TangentSpaceMeshInternal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -150,8 +150,6 @@ class InternalArray {
using ArrayType = std::variant<InternalArray<float2>, InternalArray<float3>, InternalArray<float4>,
InternalArray<ushort3>, InternalArray<ushort4>, InternalArray<quatf>>;

using AttributeMap = std::unordered_map<AttributeImpl, AttributeDataStride>;

ArrayType toArray(AttributeImpl attribute) {
switch (attribute) {
case AttributeImpl::UV1:
Expand All @@ -178,6 +176,8 @@ ArrayType toArray(AttributeImpl attribute) {
} // namespace

struct TangentSpaceMeshInput {
using AttributeMap = std::unordered_map<AttributeImpl, AttributeDataStride>;

size_t vertexCount = 0;
ushort3 const* triangles16 = nullptr;
uint3 const* triangles32 = nullptr;
Expand Down Expand Up @@ -357,7 +357,7 @@ struct TangentSpaceMeshOutput {
return std::get<InternalArray<DataType>>(attributeData[attrib]);
}

void passthrough(AttributeMap const& inAttributeMap,
void passthrough(TangentSpaceMeshInput::AttributeMap const& inAttributeMap,
std::vector<AttributeImpl> const& attributes) {
auto const borrow = [&inAttributeMap, this](AttributeImpl attrib) {
auto ref = inAttributeMap.find(attrib);
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8 changes: 8 additions & 0 deletions libs/gltfio/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -47,9 +47,17 @@ set(SRCS
src/TangentsJob.cpp
src/TangentsJob.h
src/UbershaderProvider.cpp
src/Utility.cpp
src/Utility.h
src/Wireframe.cpp
src/Wireframe.h
src/downcast.h
src/extended/AssetLoaderExtended.cpp
src/extended/AssetLoaderExtended.h
src/extended/ResourceLoaderExtended.cpp
src/extended/ResourceLoaderExtended.h
src/extended/TangentsJobExtended.cpp
src/extended/TangentsJobExtended.h
)

# ==================================================================================================
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15 changes: 15 additions & 0 deletions libs/gltfio/include/gltfio/AssetLoader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,18 @@ namespace filament::gltfio {

class NodeManager;

// Use this struct to enable mikktspace-based tangent-space computation.
/**
* \struct AssetConfigurationExtended AssetLoader.h gltfio/AssetLoader.h
* \brief extends struct AssetConfiguration
* Useful if client needs mikktspace tangents.
*/
struct AssetConfigurationExtended {
//! Optional The same parameter as provided to \struct ResourceConfiguration ResourceLoader.h
//! gltfio/ResourceLoader.h
char const* gltfPath;
};

/**
* \struct AssetConfiguration AssetLoader.h gltfio/AssetLoader.h
* \brief Construction parameters for AssetLoader.
Expand All @@ -62,6 +74,9 @@ struct AssetConfiguration {

//! Optional default node name for anonymous nodes
char* defaultNodeName = nullptr;

//! Optional to enable mikktspace tangents.
AssetConfigurationExtended* ext = nullptr;
};

/**
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1 change: 0 additions & 1 deletion libs/gltfio/include/gltfio/ResourceLoader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -156,7 +156,6 @@ class UTILS_PUBLIC ResourceLoader {

private:
bool loadResources(FFilamentAsset* asset, bool async);
void normalizeSkinningWeights(FFilamentAsset* asset) const;
struct Impl;
Impl* pImpl;
};
Expand Down
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