773 lines
30 KiB
C++
773 lines
30 KiB
C++
#include <array>
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#include <cstdint>
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#include <memory>
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#include <unordered_map>
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#include <functional>
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#include <cmath>
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#include <iostream>
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#include "../vectorlogic/vec3.hpp"
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#include "../basicdefines.hpp"
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/// @brief Finds the index of the least significant bit set to 1 in a 64-bit integer.
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/// @details Uses compiler intrinsics (_BitScanForward64, __builtin_ctzll) where available,
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/// falling back to a De Bruijn sequence multiplication lookup for portability.
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/// @param v The 64-bit integer to scan.
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/// @return The zero-based index of the lowest set bit. Behavior is undefined if v is 0.
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static inline uint32_t FindLowestOn(uint64_t v)
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{
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#if defined(_MSC_VER) && defined(TREEXY_USE_INTRINSICS)
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unsigned long index;
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_BitScanForward64(&index, v);
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return static_cast<uint32_t>(index);
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#elif (defined(__GNUC__) || defined(__clang__)) && defined(TREEXY_USE_INTRINSICS)
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return static_cast<uint32_t>(__builtin_ctzll(v));
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#else
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static const unsigned char DeBruijn[64] = {
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0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
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62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
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63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
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51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12,
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};
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// disable unary minus on unsigned warning
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#if defined(_MSC_VER) && !defined(__NVCC__)
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#pragma warning(push)
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#pragma warning(disable : 4146)
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#endif
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return DeBruijn[uint64_t((v & -v) * UINT64_C(0x022FDD63CC95386D)) >> 58];
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#if defined(_MSC_VER) && !defined(__NVCC__)
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#pragma warning(pop)
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#endif
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#endif
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}
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/// @brief Counts the number of bits set to 1 (population count) in a 64-bit integer.
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/// @details Uses compiler intrinsics (__popcnt64, __builtin_popcountll) where available,
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/// falling back to a software Hamming weight implementation.
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/// @param v The 64-bit integer to count.
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/// @return The number of bits set to 1.
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inline uint32_t CountOn(uint64_t v)
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{
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#if defined(_MSC_VER) && defined(_M_X64)
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v = __popcnt64(v);
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#elif (defined(__GNUC__) || defined(__clang__))
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v = __builtin_popcountll(v);
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#else
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// Software Implementation
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v = v - ((v >> 1) & uint64_t(0x5555555555555555));
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v = (v & uint64_t(0x3333333333333333)) + ((v >> 2) & uint64_t(0x3333333333333333));
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v = (((v + (v >> 4)) & uint64_t(0xF0F0F0F0F0F0F0F)) * uint64_t(0x101010101010101)) >> 56;
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#endif
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return static_cast<uint32_t>(v);
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}
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/// @brief A bitmask class for tracking active cells within a specific grid dimension.
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/// @tparam LOG2DIM The log base 2 of the dimension size.
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template<uint32_t LOG2DIM>
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class Mask {
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private:
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static constexpr uint32_t SIZE = std::pow(2, 3 * LOG2DIM);
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static constexpr uint32_t WORD_COUNT = SIZE / 64;
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uint64_t mWords[WORD_COUNT];
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/// @brief Internal helper to find the linear index of the first active bit.
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/// @return The index of the first on bit, or SIZE if none are set.
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uint32_t findFirstOn() const {
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const uint64_t *w = mWords;
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uint32_t n = 0;
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while (n < WORD_COUNT && !*w) {
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++w;
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++n;
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}
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return n == WORD_COUNT ? SIZE : (n << 6) + FindLowestOn(*w);
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}
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/// @brief Internal helper to find the next active bit after a specific index.
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/// @param start The index to start searching from (inclusive check, though logic implies sequential access).
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/// @return The index of the next on bit, or SIZE if none are found.
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uint32_t findNextOn(uint32_t start) const {
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uint32_t n = start >> 6;
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if (n >= WORD_COUNT) {
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return SIZE;
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}
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uint32_t m = start & 63;
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uint64_t b = mWords[n];
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if (b & (uint64_t(1) << m)) {
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return start;
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}
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b &= ~uint64_t(0) << m;
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while (!b && ++n < WORD_COUNT) {
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b = mWords[n];
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}
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return (!b ? SIZE : (n << 6) + FindLowestOn(b));
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}
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public:
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/// @brief Returns the memory size of this Mask instance.
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static size_t memUsage() {
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return sizeof(Mask);
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}
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/// @brief Returns the total capacity (number of bits) in the mask.
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static uint32_t bitCount() {
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return SIZE;
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}
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/// @brief Returns the number of 64-bit words used to store the mask.
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static uint32_t wordCount() {
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return WORD_COUNT;
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}
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/// @brief Retrieves a specific 64-bit word from the mask array.
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/// @param n The index of the word.
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/// @return The word value.
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uint64_t getWord(size_t n) const {
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return mWords[n];
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}
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/// @brief Sets a specific 64-bit word in the mask array.
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/// @param n The index of the word.
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/// @param v The value to set.
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void setWord(size_t n, uint64_t v) {
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mWords[n] = v;
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}
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/// @brief Calculates the total number of bits set to 1 in the mask.
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/// @return The count of active bits.
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uint32_t countOn() const {
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uint32_t sum = 0;
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uint32_t n = WORD_COUNT;
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for (const uint64_t* w = mWords; n--; ++w) {
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sum += CountOn(*w);
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}
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return sum;
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}
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/// @brief Iterator class for traversing set bits in the Mask.
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class Iterator {
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private:
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uint32_t mPos;
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const Mask* mParent;
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public:
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/// @brief Default constructor creating an invalid end iterator.
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Iterator() : mPos(Mask::SIZE), mParent(nullptr) {}
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/// @brief Constructor for a specific position.
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/// @param pos The current bit index.
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/// @param parent Pointer to the Mask being iterated.
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Iterator(uint32_t pos, const Mask* parent) : mPos(pos), mParent(parent) {}
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/// @brief Default assignment operator.
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Iterator& operator=(const Iterator&) = default;
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/// @brief Dereference operator.
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/// @return The index of the current active bit.
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uint32_t operator*() const {
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return mPos;
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}
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/// @brief Boolean conversion operator.
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/// @return True if the iterator is valid (not at end), false otherwise.
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operator bool() const {
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return mPos != Mask::SIZE;
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}
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/// @brief Pre-increment operator. Advances to the next active bit.
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/// @return Reference to self.
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Iterator& operator++() {
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mPos = mParent -> findNextOn(mPos + 1);
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return *this;
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}
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};
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/// @brief Default constructor. Initializes all bits to 0 (off).
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Mask() {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = 0;
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}
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}
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/// @brief Constructor initializing all bits to a specific state.
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/// @param on If true, all bits are set to 1; otherwise 0.
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Mask(bool on) {
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const uint64_t v = on ? ~uint64_t(0) : uint64_t(0);
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = v;
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}
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}
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/// @brief Copy constructor.
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Mask(const Mask &other) {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = other.mWords[i];
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}
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}
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/// @brief Reinterprets internal words as a different type and retrieves one.
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/// @tparam WordT The type to cast the pointer to (e.g., uint32_t).
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/// @param n The index in the reinterpreted array.
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/// @return The value at index n.
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template<typename WordT>
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WordT getWord(int n) const {
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return reinterpret_cast<const WordT *>(mWords)[n];
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}
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/// @brief Assignment operator.
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/// @param other The mask to copy from.
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/// @return Reference to self.
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Mask &operator=(const Mask &other) {
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// static_assert(sizeof(Mask) == sizeof(Mask), "Mismatching sizeof");
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// static_assert(WORD_COUNT == Mask::WORD_COUNT, "Mismatching word count");
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// static_assert(LOG2DIM == Mask::LOG2DIM, "Mismatching LOG2DIM");
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uint64_t *src = reinterpret_cast<const uint64_t* >(&other);
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uint64_t *dst = mWords;
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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*dst++ = *src++;
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}
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return *this;
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}
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/// @brief Equality operator.
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/// @param other The mask to compare.
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/// @return True if all bits match, false otherwise.
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bool operator==(const Mask &other) const {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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if (mWords[i] != other.mWords[i]) return false;
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}
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return true;
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}
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/// @brief Inequality operator.
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/// @param other The mask to compare.
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/// @return True if any bits differ.
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bool operator!=(const Mask &other) const {
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return !((*this) == other);
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}
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/// @brief Returns an iterator to the first active bit.
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/// @return An Iterator pointing to the first set bit.
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Iterator beginOn() const {
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return Iterator(this->findFirstOn(), this);
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}
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/// @brief Checks if a specific bit is set.
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/// @param n The bit index to check.
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/// @return True if the bit is 1, false if 0.
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bool isOn(uint32_t n) const {
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return 0 != (mWords[n >> 6] & (uint64_t(1) << (n&63)));
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}
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/// @brief Checks if all bits are set to 1.
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/// @return True if fully saturated.
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bool isOn() const {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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if (mWords[i] != ~uint64_t(0)) return false;
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}
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return true;
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}
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/// @brief Checks if all bits are set to 0.
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/// @return True if fully empty.
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bool isOff() const {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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if (mWords[i] != ~uint64_t(0)) return true;
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}
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return false;
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}
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/// @brief Sets a specific bit to 1.
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/// @param n The bit index to set.
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/// @return True if the bit was already on, false otherwise.
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bool setOn(uint32_t n) {
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uint64_t &word = mWords[n >> 6];
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const uint64_t bit = (uint64_t(1) << (n & 63));
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bool wasOn = word & bit;
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word |= bit;
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return wasOn;
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}
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/// @brief Sets a specific bit to 0.
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/// @param n The bit index to clear.
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void setOff(uint32_t n) {
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mWords[n >> 6] &= ~(uint64_t(1) << (n & 63));
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}
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/// @brief Sets a specific bit to the boolean value `On`.
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/// @param n The bit index.
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/// @param On The state to set (true=1, false=0).
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void set(uint32_t n, bool On) {
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#if 1
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auto &word = mWords[n >> 6];
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n &= 63;
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word &= ~(uint64_t(1) << n);
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word |= uint64_t(On) << n;
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#else
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On ? this->setOn(n) : this->setOff(n);
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#endif
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}
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/// @brief Sets all bits to 1.
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void setOn() {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = ~uint64_t(0);
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}
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}
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/// @brief Sets all bits to 0.
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void setOff() {
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = uint64_t(0);
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}
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}
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/// @brief Sets all bits to a specific boolean state.
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/// @param on If true, fill with 1s; otherwise 0s.
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void set(bool on) {
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const uint64_t v = on ? ~uint64_t(0) : uint64_t(0);
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for (uint32_t i = 0; i < WORD_COUNT; ++i) {
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mWords[i] = v;
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}
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}
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/// @brief Inverts (flips) all bits in the mask.
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void toggle() {
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uint32_t n = WORD_COUNT;
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for (auto* w = mWords; n--; ++w) {
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*w = ~*w;
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}
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}
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/// @brief Inverts (flips) a specific bit.
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/// @param n The bit index to toggle.
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void toggle(uint32_t n) {
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mWords[n >> 6] ^= uint64_t(1) << (n & 63);
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}
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};
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/// @brief Represents a generic grid block containing data and a presence mask.
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/// @tparam DataT The type of data stored in each cell.
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/// @tparam Log2DIM The log base 2 of the grid dimension (e.g., 3 for 8x8x8).
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template <typename DataT, int Log2DIM>
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class Grid {
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public:
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constexpr static int DIM = 1 << Log2DIM;
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constexpr static int SIZE = DIM * DIM * DIM;
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std::array<DataT, SIZE> data;
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Mask<Log2DIM> mask;
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};
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/// @brief A sparse hierarchical voxel grid container.
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/// @details Implements a 3-level structure: Root Map -> Inner Grid -> Leaf Grid.
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/// @tparam DataT The type of data stored in the leaf voxels.
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/// @tparam INNER_BITS Log2 dimension of the inner grid nodes (intermediate layer).
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/// @tparam LEAF_BITS Log2 dimension of the leaf grid nodes (data layer).
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template <typename DataT, int INNER_BITS = 2, int LEAF_BITS = 3>
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class VoxelGrid {
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public:
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constexpr static int32_t Log2N = INNER_BITS + LEAF_BITS;
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using LeafGrid = Grid<DataT, LEAF_BITS>;
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using InnerGrid = Grid<std::shared_ptr<LeafGrid>, INNER_BITS>;
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using RootMap = std::unordered_map<Vec3i, InnerGrid>;
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RootMap root_map;
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const double resolution;
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const double inv_resolution;
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const double half_resolution;
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/// @brief Constructs a VoxelGrid with a specific voxel size.
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/// @param voxel_size The size of a single voxel in world units.
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VoxelGrid(double voxel_size) : resolution(voxel_size), inv_resolution(1.0 / voxel_size), half_resolution(0.5 * voxel_size) {}
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/// @brief Calculates the approximate memory usage of the grid structure.
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/// @return The size in bytes used by the map, inner grids, and leaf grids.
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size_t getMemoryUsage() const {
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size_t total_size = 0;
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for (unsigned i = 0; i < root_map.bucket_count(); ++i) {
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size_t bucket_size = root_map.bucket_size(i);
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if (bucket_size == 0) {
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total_size++;
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} else {
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total_size += bucket_size;
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}
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}
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size_t entry_size = sizeof(Vec3i) + sizeof(InnerGrid) + sizeof(void *);
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total_size += root_map.size() * entry_size;
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for (const auto& [key, inner_grid] : root_map) {
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total_size += inner_grid.mask.countOn() * sizeof(LeafGrid);
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}
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return total_size;
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}
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/// @brief Converts a 3D float position to integer grid coordinates.
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/// @param x X coordinate.
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/// @param y Y coordinate.
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/// @param z Z coordinate.
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/// @return The integer grid coordinates.
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static inline Vec3i PosToCoord(float x, float y, float z) {
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// union VI {
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// __m128i m;
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// int32_t i[4];
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// };
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// static __m128 RES = _mm_set1_ps(inv_resolution);
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// __m128 vect = _mm_set_ps(x, y, z, 0.0);
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// __m128 res = _mm_mul_ps(vect, RES);
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// VI out;
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// out.m = _mm_cvttps_epi32(_mm_floor_ps(res));
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// return {out.i[3], out.i[2], out.i[1]};
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return Vec3f(x,y,z).floorToI();
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}
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/// @brief Converts a 3D double position to integer grid coordinates.
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/// @param x X coordinate.
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/// @param y Y coordinate.
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/// @param z Z coordinate.
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/// @return The integer grid coordinates.
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static inline Vec3i posToCoord(double x, double y, double z) {
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return Vec3f(x,y,z).floorToI();
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}
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/// @brief Converts a Vec3d position to integer grid coordinates.
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/// @param pos The position vector.
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/// @return The integer grid coordinates.
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static inline Vec3i posToCoord(const Vec3d &pos) {
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return pos.floorToI();
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}
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/// @brief Converts integer grid coordinates back to world position (center of voxel).
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/// @param coord The grid coordinate.
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/// @return The world position center of the voxel.
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Vec3d Vec3iToPos(const Vec3i& coord) const {
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return (coord.toDouble() * resolution) + half_resolution;
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}
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/// @brief Iterates over every active cell in the grid and applies a visitor function.
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/// @tparam VisitorFunction The type of the callable (DataT& val, Vec3i pos).
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/// @param func The function to execute for each active voxel.
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template <class VisitorFunction>
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void forEachCell(VisitorFunction func) {
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constexpr static int32_t MASK_LEAF = ((1 << LEAF_BITS) - 1);
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constexpr static int32_t MASK_INNER = ((1 << INNER_BITS) - 1);
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for (auto& map_it : root_map) {
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const Vec3i& root_coord = map_it.first;
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int32_t xA = root_coord.x;
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int32_t yA = root_coord.y;
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int32_t zA = root_coord.z;
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InnerGrid& inner_grid = map_it.second;
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auto& mask2 = inner_grid.mask;
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for (auto inner_it = mask2.beginOn(); inner_it; ++inner_it) {
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const int32_t inner_index = *inner_it;
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int32_t xB = xA | ((inner_index & MASK_INNER) << LEAF_BITS);
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int32_t yB = yA | (((inner_index >> INNER_BITS) & MASK_INNER) << LEAF_BITS);
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int32_t zB = zA | (((inner_index >> (INNER_BITS* 2)) & MASK_INNER) << LEAF_BITS);
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auto& leaf_grid = inner_grid.data[inner_index];
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auto& mask1 = leaf_grid->mask;
|
|
for (auto leaf_it = mask1.beginOn(); leaf_it; ++leaf_it){
|
|
const int32_t leaf_index = *leaf_it;
|
|
Vec3i pos = Vec3i(xB | (leaf_index & MASK_LEAF),
|
|
yB | ((leaf_index >> LEAF_BITS) & MASK_LEAF),
|
|
zB | ((leaf_index >> (LEAF_BITS * 2)) & MASK_LEAF));
|
|
func(leaf_grid->data[leaf_index], pos);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// @brief Helper class to accelerate random access to the VoxelGrid by caching recent paths.
|
|
class Accessor {
|
|
private:
|
|
RootMap &root_;
|
|
Vec3i prev_root_coord_;
|
|
Vec3i prev_inner_coord_;
|
|
InnerGrid* prev_inner_ptr_ = nullptr;
|
|
LeafGrid* prev_leaf_ptr_ = nullptr;
|
|
public:
|
|
/// @brief Constructs an Accessor for a specific root map.
|
|
/// @param root Reference to the grid's root map.
|
|
Accessor(RootMap& root) : root_(root) {}
|
|
|
|
/// @brief Sets a value at a specific coordinate, creating nodes if they don't exist.
|
|
/// @param coord The grid coordinate.
|
|
/// @param value The value to store.
|
|
/// @return True if the voxel was already active, false if it was newly activated.
|
|
bool setValue(const Vec3i& coord, const DataT& value) {
|
|
LeafGrid* leaf_ptr = prev_leaf_ptr_;
|
|
const Vec3i inner_key = getInnerKey(coord);
|
|
if (inner_key != prev_inner_coord_ || !prev_leaf_ptr_) {
|
|
InnerGrid* inner_ptr = prev_inner_ptr_;
|
|
const Vec3i root_key = getRootKey(coord);
|
|
if (root_key != prev_root_coord_ || !prev_inner_ptr_) {
|
|
auto root_it = root_.find(root_key);
|
|
if (root_it == root_.end()) {
|
|
root_it = root_.insert({root_key, InnerGrid()}).first;
|
|
}
|
|
|
|
inner_ptr = &(root_it->second);
|
|
prev_root_coord_ = root_key;
|
|
prev_inner_ptr_ = inner_ptr;
|
|
}
|
|
|
|
const uint32_t inner_index = getInnerIndex(coord);
|
|
auto& inner_data = inner_ptr->data[inner_index];
|
|
if (inner_ptr->mask.setOn(inner_index) == false) {
|
|
inner_data = std::make_shared<LeafGrid>();
|
|
}
|
|
|
|
leaf_ptr = inner_data.get();
|
|
prev_inner_coord_ = inner_key;
|
|
prev_leaf_ptr_ = leaf_ptr;
|
|
}
|
|
|
|
const uint32_t leaf_index = getLeafIndex(coord);
|
|
bool was_on = leaf_ptr->mask.setOn(leaf_index);
|
|
leaf_ptr->data[leaf_index] = value;
|
|
return was_on;
|
|
}
|
|
|
|
/// @brief Retrieves a pointer to the value at a coordinate.
|
|
/// @param coord The grid coordinate.
|
|
/// @return Pointer to the data if active, otherwise nullptr.
|
|
DataT* value(const Vec3i& coord) {
|
|
LeafGrid* leaf_ptr = prev_leaf_ptr_;
|
|
const Vec3i inner_key = getInnerKey(coord);
|
|
if (inner_key != prev_inner_coord_ || !prev_inner_ptr_) {
|
|
InnerGrid* inner_ptr = prev_inner_ptr_;
|
|
const Vec3i root_key = getRootKey(coord);
|
|
|
|
if (root_key != prev_root_coord_ || !prev_inner_ptr_) {
|
|
auto it = root_.find(root_key);
|
|
if (it == root_.end()) {
|
|
return nullptr;
|
|
}
|
|
inner_ptr = &(it->second);
|
|
prev_inner_coord_ = root_key;
|
|
prev_inner_ptr_ = inner_ptr;
|
|
}
|
|
|
|
const uint32_t inner_index = getInnerIndex(coord);
|
|
auto& inner_data = inner_ptr->data[inner_index];
|
|
|
|
if (!inner_ptr->mask.isOn(inner_index)) {
|
|
return nullptr;
|
|
}
|
|
|
|
leaf_ptr = inner_ptr->data[inner_index].get();
|
|
prev_inner_coord_ = inner_key;
|
|
prev_leaf_ptr_ = leaf_ptr;
|
|
}
|
|
|
|
const uint32_t leaf_index = getLeafIndex(coord);
|
|
if (!leaf_ptr->mask.isOn(leaf_index)) {
|
|
return nullptr;
|
|
}
|
|
|
|
return &(leaf_ptr->data[leaf_index]);
|
|
}
|
|
|
|
/// @brief Returns the most recently accessed InnerGrid pointer.
|
|
/// @return Pointer to the cached InnerGrid.
|
|
const InnerGrid* lastInnerGrid() const {
|
|
return prev_inner_ptr_;
|
|
}
|
|
|
|
/// @brief Returns the most recently accessed LeafGrid pointer.
|
|
/// @return Pointer to the cached LeafGrid.
|
|
const LeafGrid* lastLeafGrid() const {
|
|
return prev_leaf_ptr_;
|
|
}
|
|
};
|
|
|
|
/// @brief Creates a new Accessor instance for this grid.
|
|
/// @return An Accessor object.
|
|
Accessor createAccessor() {
|
|
return Accessor(root_map);
|
|
}
|
|
|
|
/// @brief Computes the key for the RootMap based on global coordinates.
|
|
/// @param coord The global grid coordinate.
|
|
/// @return The base coordinate for the root key (masked).
|
|
static inline Vec3i getRootKey(const Vec3i& coord) {
|
|
constexpr static int32_t MASK = ~((1 << Log2N) - 1);
|
|
return {coord.x & MASK, coord.y & MASK, coord.z & MASK};
|
|
}
|
|
|
|
/// @brief Computes the key for locating an InnerGrid (intermediate block).
|
|
/// @param coord The global grid coordinate.
|
|
/// @return The coordinate masked to the InnerGrid resolution.
|
|
static inline Vec3i getInnerKey(const Vec3i &coord)
|
|
{
|
|
constexpr static int32_t MASK = ~((1 << LEAF_BITS) - 1);
|
|
return {coord.x & MASK, coord.y & MASK, coord.z & MASK};
|
|
}
|
|
|
|
/// @brief Computes the linear index within an InnerGrid for a given coordinate.
|
|
/// @param coord The global grid coordinate.
|
|
/// @return The linear index (0 to size of InnerGrid).
|
|
static inline uint32_t getInnerIndex(const Vec3i &coord)
|
|
{
|
|
constexpr static int32_t MASK = ((1 << INNER_BITS) - 1);
|
|
// clang-format off
|
|
return ((coord.x >> LEAF_BITS) & MASK) +
|
|
(((coord.y >> LEAF_BITS) & MASK) << INNER_BITS) +
|
|
(((coord.z >> LEAF_BITS) & MASK) << (INNER_BITS * 2));
|
|
// clang-format on
|
|
}
|
|
|
|
/// @brief Computes the linear index within a LeafGrid for a given coordinate.
|
|
/// @param coord The global grid coordinate.
|
|
/// @return The linear index (0 to size of LeafGrid).
|
|
static inline uint32_t getLeafIndex(const Vec3i &coord)
|
|
{
|
|
constexpr static int32_t MASK = ((1 << LEAF_BITS) - 1);
|
|
// clang-format off
|
|
return (coord.x & MASK) +
|
|
((coord.y & MASK) << LEAF_BITS) +
|
|
((coord.z & MASK) << (LEAF_BITS * 2));
|
|
// clang-format on
|
|
}
|
|
|
|
/// @brief Sets the color of a voxel at a specific world position.
|
|
/// @details Assumes DataT is compatible with Vec3ui8.
|
|
/// @param worldPos The 3D world position.
|
|
/// @param color The color value to set.
|
|
/// @return True if the voxel previously existed, false if created.
|
|
bool setVoxelColor(const Vec3d& worldPos, const Vec3ui8& color) {
|
|
Vec3i coord = posToCoord(worldPos);
|
|
Accessor accessor = createAccessor();
|
|
return accessor.setValue(coord, color);
|
|
}
|
|
|
|
/// @brief Retrieves the color of a voxel at a specific world position.
|
|
/// @details Assumes DataT is compatible with Vec3ui8.
|
|
/// @param worldPos The 3D world position.
|
|
/// @return Pointer to the color if exists, nullptr otherwise.
|
|
Vec3ui8* getVoxelColor(const Vec3d& worldPos) {
|
|
Vec3i coord = posToCoord(worldPos);
|
|
Accessor accessor = createAccessor();
|
|
return accessor.value(coord);
|
|
}
|
|
|
|
/// @brief Renders the grid to an RGB buffer
|
|
/// @details Iterates all cells and projects them onto a 2D plane defined by viewDir and upDir.
|
|
/// @param buffer The output buffer (will be resized to width * height * 3).
|
|
/// @param width Width of the output image.
|
|
/// @param height Height of the output image.
|
|
/// @param viewOrigin the position of the camera
|
|
/// @param viewDir The direction the camera is looking.
|
|
/// @param upDir The up vector of the camera.
|
|
/// @param fov the field of view for the camera
|
|
void renderToRGB(std::vector<uint8_t>& buffer, int width, int height, const Vec3d& viewOrigin,
|
|
const Vec3d& viewDir, const Vec3d& upDir, float fov = 80) {
|
|
// Resize buffer to hold width * height * 3 bytes (RGB)
|
|
buffer.resize(width * height * 3);
|
|
std::fill(buffer.begin(), buffer.end(), 0);
|
|
|
|
// Normalize view direction and compute right vector
|
|
Vec3d viewDirN = viewDir.normalized();
|
|
Vec3d upDirN = upDir.normalized();
|
|
Vec3d rightDir = viewDirN.cross(upDirN).normalized();
|
|
|
|
// Recompute up vector to ensure orthogonality
|
|
Vec3d realUpDir = rightDir.cross(viewDirN).normalized();
|
|
|
|
// Compute focal length based on FOV
|
|
double aspectRatio = static_cast<double>(width) / static_cast<double>(height);
|
|
double fovRad = fov * M_PI / 180.0;
|
|
double focalLength = 1.0 / tan(fovRad * 0.5);
|
|
|
|
// Precompute scaling factors for screen coordinates
|
|
double pixelWidth = 2.0 / (width - 1);
|
|
double pixelHeight = 2.0 / (height - 1);
|
|
|
|
// Compute half voxel size for accurate ray-voxel intersection
|
|
double halfVoxel = resolution * 0.5;
|
|
|
|
// Create an accessor for efficient voxel lookup
|
|
Accessor accessor = createAccessor();
|
|
|
|
// For each pixel in the output image
|
|
for (int y = 0; y < height; ++y) {
|
|
for (int x = 0; x < width; ++x) {
|
|
// Convert pixel coordinates to normalized device coordinates [-1, 1]
|
|
double ndcX = (2.0 * x / (width - 1)) - 1.0;
|
|
double ndcY = 1.0 - (2.0 * y / (height - 1)); // Flip Y
|
|
|
|
// Scale by aspect ratio
|
|
ndcX *= aspectRatio;
|
|
|
|
// Compute ray direction in camera space
|
|
Vec3d rayDirCam(ndcX, ndcY, focalLength);
|
|
|
|
// Transform ray direction to world space
|
|
Vec3d rayDirWorld = (rightDir * rayDirCam.x) +
|
|
(realUpDir * rayDirCam.y) +
|
|
(viewDirN * rayDirCam.z);
|
|
rayDirWorld = rayDirWorld.normalized();
|
|
|
|
// Set up ray marching
|
|
Vec3d rayPos = viewOrigin;
|
|
double maxDistance = 100.0; // Maximum ray distance
|
|
double stepSize = resolution; // Step size for ray marching
|
|
|
|
// Ray marching loop
|
|
for (double t = 0; t < maxDistance; t += stepSize) {
|
|
rayPos = viewOrigin + rayDirWorld * t;
|
|
|
|
// Convert world position to voxel coordinate
|
|
Vec3i coord = posToCoord(rayPos);
|
|
|
|
// Look up voxel value using accessor (cached for efficiency)
|
|
DataT* voxelData = accessor.value(coord);
|
|
|
|
if (voxelData) {
|
|
// Voxel hit - extract color
|
|
// Assuming DataT is Vec3ui8 or compatible
|
|
Vec3ui8* colorPtr = reinterpret_cast<Vec3ui8*>(voxelData);
|
|
|
|
// Get buffer index for this pixel
|
|
size_t pixelIdx = (y * width + x) * 3;
|
|
|
|
// Apply simple shading based on normal
|
|
// Estimate normal by checking neighbors
|
|
double shading = 1.0;
|
|
|
|
// Check neighboring voxels to estimate surface normal
|
|
Vec3d voxelCenter = Vec3iToPos(coord);
|
|
Vec3d toRay = (rayPos - voxelCenter).normalized();
|
|
|
|
// Simple normal estimation by checking adjacent voxels
|
|
Vec3i neighbors[6] = {
|
|
Vec3i(coord.x + 1, coord.y, coord.z),
|
|
Vec3i(coord.x - 1, coord.y, coord.z),
|
|
Vec3i(coord.x, coord.y + 1, coord.z),
|
|
Vec3i(coord.x, coord.y - 1, coord.z),
|
|
Vec3i(coord.x, coord.y, coord.z + 1),
|
|
Vec3i(coord.x, coord.y, coord.z - 1)
|
|
};
|
|
|
|
// Count empty neighbors to estimate surface orientation
|
|
int emptyCount = 0;
|
|
for (int i = 0; i < 6; ++i) {
|
|
if (!accessor.value(neighbors[i])) {
|
|
emptyCount++;
|
|
}
|
|
}
|
|
|
|
// Simple shading: more visible if fewer neighbors (edge/corner)
|
|
if (emptyCount > 0) {
|
|
shading = 0.7 + 0.3 * (emptyCount / 6.0);
|
|
}
|
|
|
|
// Store color in buffer with shading
|
|
buffer[pixelIdx] = static_cast<uint8_t>(colorPtr->x * shading);
|
|
buffer[pixelIdx + 1] = static_cast<uint8_t>(colorPtr->y * shading);
|
|
buffer[pixelIdx + 2] = static_cast<uint8_t>(colorPtr->z * shading);
|
|
|
|
break; // Stop ray marching after hitting first voxel
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}; |