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filament/libs/geometry/src/TangentSpaceMesh.cpp
2023-03-31 12:03:49 -07:00

599 lines
20 KiB
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/*
* Copyright (C) 2023 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <geometry/TangentSpaceMesh.h>
#include "MikktspaceImpl.h"
#include "TangentSpaceMeshInternal.h"
#include <math/mat3.h>
#include <math/norm.h>
#include <utils/Log.h>
#include <utils/Panic.h>
#include <vector>
namespace filament {
namespace geometry {
using namespace filament::math;
using Builder = TangentSpaceMesh::Builder;
using Algorithm = TangentSpaceMesh::Algorithm;
using MethodPtr = void(*)(TangentSpaceMeshInput const*, TangentSpaceMeshOutput*);
namespace {
uint8_t const NORMALS_BIT = 0x01;
uint8_t const UVS_BIT = 0x02;
uint8_t const POSITIONS_BIT = 0x04;
uint8_t const INDICES_BIT = 0x08;
// Input types
uint8_t const NORMALS = NORMALS_BIT;
uint8_t const POSITIONS_INDICES = POSITIONS_BIT | INDICES_BIT;
uint8_t const NORMALS_UVS_POSITIONS_INDICES = NORMALS_BIT | UVS_BIT | POSITIONS_BIT | INDICES_BIT;
std::string_view to_string(Algorithm const algorithm) noexcept {
switch (algorithm) {
case Algorithm::DEFAULT:
return "DEFAULT";
case Algorithm::MIKKTSPACE:
return "MIKKTSPACE";
case Algorithm::LENGYEL:
return "LENGYEL";
case Algorithm::HUGHES_MOLLER:
return "HUGHES_MOLLER";
case Algorithm::FRISVAD:
return "FRISVAD";
case Algorithm::FLAT_SHADING:
return "FLAT_SHADING";
}
}
inline bool isInputType(uint8_t const inputType, uint8_t const checkType) noexcept {
return ((inputType & checkType) == checkType);
}
template <typename InputType>
inline void takeStride(InputType*& out, size_t const stride) noexcept {
out = pointerAdd(out, 1, stride);
}
inline Algorithm selectBestDefaultAlgorithm(uint8_t const inputType) {
Algorithm outAlgo;
if (isInputType(inputType, NORMALS_UVS_POSITIONS_INDICES)) {
outAlgo = Algorithm::MIKKTSPACE;
} else if (isInputType(inputType, POSITIONS_INDICES)) {
outAlgo = Algorithm::FLAT_SHADING;
} else {
ASSERT_PRECONDITION(inputType & NORMALS,
"Must at least have normals or (positions + indices) as input");
outAlgo = Algorithm::FRISVAD;
}
return outAlgo;
}
Algorithm selectAlgorithm(TangentSpaceMeshInput *input) noexcept {
uint8_t inputType = 0;
if (input->normals) {
inputType |= NORMALS_BIT;
}
if (input->positions) {
inputType |= POSITIONS_BIT;
}
if (input->uvs) {
inputType |= UVS_BIT;
}
if (input->triangles32 || input->triangles16) {
inputType |= INDICES_BIT;
}
bool foundAlgo = false;
Algorithm outAlgo = Algorithm::DEFAULT;
switch (input->algorithm) {
case Algorithm::DEFAULT:
outAlgo = selectBestDefaultAlgorithm(inputType);
foundAlgo = true;
break;
case Algorithm::MIKKTSPACE:
if (isInputType(inputType, NORMALS_UVS_POSITIONS_INDICES)) {
outAlgo = Algorithm::MIKKTSPACE;
foundAlgo = true;
}
break;
case Algorithm::LENGYEL:
if (isInputType(inputType, NORMALS_UVS_POSITIONS_INDICES)) {
outAlgo = Algorithm::LENGYEL;
foundAlgo = true;
}
break;
case Algorithm::HUGHES_MOLLER:
if (isInputType(inputType, NORMALS)) {
outAlgo = Algorithm::HUGHES_MOLLER;
foundAlgo = true;
}
break;
case Algorithm::FRISVAD:
if (isInputType(inputType, NORMALS)) {
outAlgo = Algorithm::FRISVAD;
foundAlgo = true;
}
break;
case Algorithm::FLAT_SHADING:
if (isInputType(inputType, POSITIONS_INDICES)) {
outAlgo = Algorithm::FLAT_SHADING;
foundAlgo = true;
}
break;
}
if (!foundAlgo) {
outAlgo = selectBestDefaultAlgorithm(inputType);
utils::slog.w << "Cannot satisfy algorithm=" << to_string(input->algorithm)
<< ". Selected algorithm=" << to_string(outAlgo) << " instead"
<< utils::io::endl;
}
return outAlgo;
}
// The paper uses a Z-up world basis, which has been converted to Y-up here
inline std::pair<float3, float3> frisvadKernel(float3 const& n) {
float3 b, t;
if (n.y < -1.0f + std::numeric_limits<float>::epsilon()) {
// Handle the singularity
t = float3{-1.0f, 0.0f, 0.0f};
b = float3{0.0f, 0.0f, -1.0f};
} else {
float const va = 1.0f / (1.0f + n.y);
float const vb = -n.z * n.x * va;
t = float3{vb, -n.z, 1.0f - n.z * n.z * va};
b = float3{1.0f - n.x * n.x * va, -n.x, vb};
}
return {b, t};
}
void frisvadMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* output)
noexcept {
size_t const vertexCount = input->vertexCount;
quatf* quats = output->tangentSpace.allocate(vertexCount);
float3 const* UTILS_RESTRICT normals = input->normals;
size_t nstride = input->normalStride ? input->normalStride : sizeof(float3);
for (size_t qindex = 0; qindex < vertexCount; ++qindex) {
float3 const n = *normals;
auto const [b, t] = frisvadKernel(n);
quats[qindex] = mat3f::packTangentFrame({t, b, n}, sizeof(int32_t));
normals = pointerAdd(normals, 1, nstride);
}
output->vertexCount = input->vertexCount;
output->triangleCount = input->triangleCount;
output->uvs.borrow(input->uvs);
output->positions.borrow(input->positions);
output->triangles32.borrow(input->triangles32);
output->triangles16.borrow(input->triangles16);
}
void hughesMollerMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* output)
noexcept {
size_t const vertexCount = input->vertexCount;
quatf* quats = output->tangentSpace.allocate(vertexCount);
float3 const* UTILS_RESTRICT normals = input->normals;
size_t nstride = input->normalStride ? input->normalStride : sizeof(float3);
for (size_t qindex = 0; qindex < vertexCount; ++qindex) {
float3 const n = *normals;
float3 b, t;
if (abs(n.x) > abs(n.z) + std::numeric_limits<float>::epsilon()) {
t = float3{-n.y, n.x, 0.0f};
} else {
t = float3{0.0f, -n.z, n.y};
}
t = normalize(t);
b = cross(n, t);
quats[qindex] = mat3f::packTangentFrame({t, b, n}, sizeof(int32_t));
normals = pointerAdd(normals, 1, nstride);
}
output->vertexCount = input->vertexCount;
output->triangleCount = input->triangleCount;
output->uvs.borrow(input->uvs);
output->positions.borrow(input->positions);
output->triangles32.borrow(input->triangles32);
output->triangles16.borrow(input->triangles16);
}
void flatShadingMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* output)
noexcept {
float3 const* positions = input->positions;
size_t const pstride = input->positionStride ? input->positionStride : sizeof(float3);
float2 const* uvs = input->uvs;
size_t const uvstride = input->uvStride ? input->uvStride : sizeof(float2);
bool const isTriangle16 = input->triangles16 != nullptr;
uint8_t const* triangles = isTriangle16 ? (uint8_t const*) input->triangles16 :
(uint8_t const*) input->triangles32;
size_t const triangleCount = input->triangleCount;
size_t const tstride = isTriangle16 ? sizeof(ushort3) : sizeof(uint3);
size_t const outVertexCount = triangleCount * 3;
float3* outPositions = output->positions.allocate(outVertexCount);
float2* outUvs = uvs ? output->uvs.allocate(outVertexCount) : nullptr;
quatf* quats = output->tangentSpace.allocate(outVertexCount);
size_t const outTriangleCount = triangleCount;
uint3* outTriangles = output->triangles32.allocate(outTriangleCount);
size_t vindex = 0;
for (size_t tindex = 0; tindex < triangleCount; ++tindex) {
uint3 tri = isTriangle16 ?
uint3(*(ushort3*)(pointerAdd(triangles, tindex, tstride))) :
*(uint3*)(pointerAdd(triangles, tindex, tstride));
float3 const pa = *pointerAdd(positions, tri.x, pstride);
float3 const pb = *pointerAdd(positions, tri.y, pstride);
float3 const pc = *pointerAdd(positions, tri.z, pstride);
uint32_t i0 = vindex++, i1 = vindex++, i2 = vindex++;
outTriangles[tindex] = uint3{i0, i1, i2};
outPositions[i0] = pa;
outPositions[i1] = pb;
outPositions[i2] = pc;
float3 const n = normalize(cross(pc - pb, pa - pb));
const auto [t, b] = frisvadKernel(n);
quatf const tspace = mat3f::packTangentFrame({t, b, n}, sizeof(int32_t));
quats[i0] = tspace;
quats[i1] = tspace;
quats[i2] = tspace;
if (outUvs) {
outUvs[i0] = *pointerAdd(uvs, tri.x, uvstride);
outUvs[i1] = *pointerAdd(uvs, tri.y, uvstride);
outUvs[i2] = *pointerAdd(uvs, tri.z, uvstride);
}
}
output->vertexCount = outVertexCount;
output->triangleCount = outTriangleCount;
}
void mikktspaceMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* output) {
MikktspaceImpl impl(input);
impl.run(output);
}
inline float3 randomPerp(float3 const& n) {
float3 perp = cross(n, float3{1, 0, 0});
float sqrlen = dot(perp, perp);
if (sqrlen <= std::numeric_limits<float>::epsilon()) {
perp = cross(n, float3{0, 1, 0});
sqrlen = dot(perp, perp);
}
return perp / sqrlen;
}
void lengyelMethod(TangentSpaceMeshInput const* input, TangentSpaceMeshOutput* output) {
size_t const vertexCount = input->vertexCount;
size_t const triangleCount = input->triangleCount;
size_t const positionStride = input->positionStride ? input->positionStride : sizeof(float3);
size_t const normalStride = input->normalStride ? input->normalStride : sizeof(float3);
size_t const uvStride = input->uvStride ? input->uvStride : sizeof(float2);
auto const* triangles16 = input->triangles16;
auto const* triangles32 = input->triangles32;
auto const* positions = input->positions;
auto const* uvs = input->uvs;
auto const* normals = input->normals;
std::vector<float3> tan1(vertexCount, float3{0.0f});
std::vector<float3> tan2(vertexCount, float3{0.0f});
for (size_t a = 0; a < triangleCount; ++a) {
uint3 tri = triangles16 ? uint3(triangles16[a]) : triangles32[a];
assert_invariant(tri.x < vertexCount && tri.y < vertexCount && tri.z < vertexCount);
float3 const& v1 = *pointerAdd(positions, tri.x, positionStride);
float3 const& v2 = *pointerAdd(positions, tri.y, positionStride);
float3 const& v3 = *pointerAdd(positions, tri.z, positionStride);
float2 const& w1 = *pointerAdd(uvs, tri.x, uvStride);
float2 const& w2 = *pointerAdd(uvs, tri.y, uvStride);
float2 const& w3 = *pointerAdd(uvs, tri.z, uvStride);
float const x1 = v2.x - v1.x;
float const x2 = v3.x - v1.x;
float const y1 = v2.y - v1.y;
float const y2 = v3.y - v1.y;
float const z1 = v2.z - v1.z;
float const z2 = v3.z - v1.z;
float const s1 = w2.x - w1.x;
float const s2 = w3.x - w1.x;
float const t1 = w2.y - w1.y;
float const t2 = w3.y - w1.y;
float const d = s1 * t2 - s2 * t1;
float3 sdir, tdir;
// In general we can't guarantee smooth tangents when the UV's are non-smooth, but let's at
// least avoid divide-by-zero and fall back to normals-only method.
if (d == 0.0) {
float3 const& n1 = *pointerAdd(normals, tri.x, normalStride);
sdir = randomPerp(n1);
tdir = cross(n1, sdir);
} else {
sdir = {t2 * x1 - t1 * x2, t2 * y1 - t1 * y2, t2 * z1 - t1 * z2};
tdir = {s1 * x2 - s2 * x1, s1 * y2 - s2 * y1, s1 * z2 - s2 * z1};
float const r = 1.0f / d;
sdir *= r;
tdir *= r;
}
tan1[tri.x] += sdir;
tan1[tri.y] += sdir;
tan1[tri.z] += sdir;
tan2[tri.x] += tdir;
tan2[tri.y] += tdir;
tan2[tri.z] += tdir;
}
quatf* quats = output->tangentSpace.allocate(vertexCount);
for (size_t a = 0; a < vertexCount; a++) {
float3 const& n = *pointerAdd(normals, a, normalStride);
float3 const& t1 = tan1[a];
float3 const& t2 = tan2[a];
// Gram-Schmidt orthogonalize
float3 const t = normalize(t1 - n * dot(n, t1));
// Calculate handedness
float const w = (dot(cross(n, t1), t2) < 0.0f) ? -1.0f : 1.0f;
float3 b = w < 0 ? cross(t, n) : cross(n, t);
quats[a] = mat3f::packTangentFrame({t, b, n}, sizeof(int32_t));
}
output->vertexCount = vertexCount;
output->triangleCount = triangleCount;
output->uvs.borrow(uvs);
output->positions.borrow(positions);
output->triangles32.borrow(triangles32);
output->triangles16.borrow(triangles16);
}
} // anonymous namespace
Builder::Builder() noexcept
:mMesh(new TangentSpaceMesh()) {}
Builder::~Builder() noexcept {
delete mMesh;
}
Builder::Builder(Builder&& that) noexcept {
std::swap(mMesh, that.mMesh);
}
Builder& Builder::operator=(Builder&& that) noexcept {
std::swap(mMesh, that.mMesh);
return *this;
}
Builder& Builder::vertexCount(size_t vertexCount) noexcept {
mMesh->mInput->vertexCount = vertexCount;
return *this;
}
Builder& Builder::normals(float3 const* normals, size_t stride) noexcept {
mMesh->mInput->normals = normals;
mMesh->mInput->normalStride = stride;
return *this;
}
Builder& Builder::uvs(float2 const* uvs, size_t stride) noexcept {
mMesh->mInput->uvs = uvs;
mMesh->mInput->uvStride = stride;
return *this;
}
Builder& Builder::positions(float3 const* positions, size_t stride) noexcept {
mMesh->mInput->positions = positions;
mMesh->mInput->positionStride = stride;
return *this;
}
Builder& Builder::triangleCount(size_t triangleCount) noexcept {
mMesh->mInput->triangleCount = triangleCount;
return *this;
}
Builder& Builder::triangles(uint3 const* triangle32) noexcept {
mMesh->mInput->triangles32 = triangle32;
return *this;
}
Builder& Builder::triangles(ushort3 const* triangle16) noexcept {
mMesh->mInput->triangles16 = triangle16;
return *this;
}
Builder& Builder::algorithm(Algorithm algo) noexcept {
mMesh->mInput->algorithm = algo;
return *this;
}
TangentSpaceMesh* Builder::build() {
ASSERT_PRECONDITION(!mMesh->mInput->triangles32 || !mMesh->mInput->triangles16,
"Cannot provide both uint32 triangles and uint16 triangles");
// Work in progress. Not for use.
mMesh->mOutput->algorithm = selectAlgorithm(mMesh->mInput);
MethodPtr method = nullptr;
switch (mMesh->mOutput->algorithm) {
case Algorithm::MIKKTSPACE:
method = mikktspaceMethod;
break;
case Algorithm::LENGYEL:
method = lengyelMethod;
break;
case Algorithm::HUGHES_MOLLER:
method = hughesMollerMethod;
break;
case Algorithm::FRISVAD:
method = frisvadMethod;
break;
case Algorithm::FLAT_SHADING:
method = flatShadingMethod;
break;
default:
break;
}
assert_invariant(method);
method(mMesh->mInput, mMesh->mOutput);
auto meshPtr = mMesh;
// Reset the state.
mMesh = new TangentSpaceMesh();
return meshPtr;
}
void TangentSpaceMesh::destroy(TangentSpaceMesh* mesh) noexcept {
delete mesh;
}
TangentSpaceMesh::TangentSpaceMesh() noexcept
:mInput(new TangentSpaceMeshInput()), mOutput(new TangentSpaceMeshOutput()) {
}
TangentSpaceMesh::~TangentSpaceMesh() noexcept {
delete mOutput;
delete mInput;
}
TangentSpaceMesh::TangentSpaceMesh(TangentSpaceMesh&& that) noexcept {
std::swap(mInput, that.mInput);
std::swap(mOutput, that.mOutput);
}
TangentSpaceMesh& TangentSpaceMesh::operator=(TangentSpaceMesh&& that) noexcept {
std::swap(mInput, that.mInput);
std::swap(mOutput, that.mOutput);
return *this;
}
size_t TangentSpaceMesh::getVertexCount() const noexcept {
return mOutput->vertexCount;
}
void TangentSpaceMesh::getPositions(float3* positions, size_t stride) const {
ASSERT_PRECONDITION(mInput->positions, "Must provide input positions");
stride = stride ? stride : sizeof(decltype(*positions));
auto outPositions = mOutput->positions.get();
for (size_t i = 0; i < mOutput->vertexCount; ++i) {
*positions = outPositions[i];
takeStride(positions, stride);
}
}
void TangentSpaceMesh::getUVs(float2* uvs, size_t stride) const {
ASSERT_PRECONDITION(mInput->uvs, "Must provide input UVs");
stride = stride ? stride : sizeof(decltype(*uvs));
auto outUvs = mOutput->uvs.get();
for (size_t i = 0; i < mOutput->vertexCount; ++i) {
*uvs = outUvs[i];
takeStride(uvs, stride);
}
}
size_t TangentSpaceMesh::getTriangleCount() const noexcept {
return mOutput->triangleCount;
}
void TangentSpaceMesh::getTriangles(uint3* out) const {
ASSERT_PRECONDITION(mInput->triangles16 || mInput->triangles32, "Must provide input triangles");
bool const is16 = (bool) mOutput->triangles16;
auto triangles16 = mOutput->triangles16.get();
auto triangles32 = mOutput->triangles32.get();
size_t const stride = sizeof(decltype(*out));
for (size_t i = 0; i < mOutput->triangleCount; ++i) {
*out = is16 ? uint3{triangles16[i]} : triangles32[i];
takeStride(out, stride);
}
}
void TangentSpaceMesh::getTriangles(ushort3* out) const {
ASSERT_PRECONDITION(mInput->triangles16 || mInput->triangles32, "Must provide input triangles");
const bool is16 = (bool) mOutput->triangles16;
auto triangles16 = mOutput->triangles16.get();
auto triangles32 = mOutput->triangles32.get();
const size_t stride = sizeof(decltype(*out));
for (size_t i = 0, c = mOutput->triangleCount; i < c; ++i) {
if (is16) {
*out = triangles16[i];
} else {
uint3 const& tri = triangles32[i];
ASSERT_PRECONDITION(tri.x <= USHRT_MAX &&
tri.y <= USHRT_MAX &&
tri.z <= USHRT_MAX, "Overflow when casting uint3 to ushort3");
*out = ushort3{static_cast<uint16_t>(tri.x),
static_cast<uint16_t>(tri.y),
static_cast<uint16_t>(tri.z)};
}
takeStride(out, stride);
}
}
void TangentSpaceMesh::getQuats(quatf* out, size_t stride) const noexcept {
stride = stride ? stride : sizeof(decltype((*out)));
auto tangentSpace = mOutput->tangentSpace.get();
size_t const vertexCount = mOutput->vertexCount;
for (size_t i = 0; i < vertexCount; ++i) {
*out = tangentSpace[i];
takeStride(out, stride);
}
}
void TangentSpaceMesh::getQuats(short4* out, size_t stride) const noexcept {
stride = stride ? stride : sizeof(decltype((*out)));
auto tangentSpace = mOutput->tangentSpace.get();
size_t const vertexCount = mOutput->vertexCount;
for (size_t i = 0; i < vertexCount; ++i) {
*out = packSnorm16(tangentSpace[i].xyzw);
takeStride(out, stride);
}
}
void TangentSpaceMesh::getQuats(quath* out, size_t stride) const noexcept {
stride = stride ? stride : sizeof(decltype((*out)));
auto tangentSpace = mOutput->tangentSpace.get();
size_t const vertexCount = mOutput->vertexCount;
for (size_t i = 0; i < vertexCount; ++i) {
*out = quath(tangentSpace[i].xyzw);
takeStride(out, stride);
}
}
Algorithm TangentSpaceMesh::getAlgorithm() const noexcept {
return mOutput->algorithm;
}
}
}