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tMax was slower with the precompute.

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Yggdrasil75
2026-01-22 10:08:47 -05:00
parent 5ef07c6af5
commit 5d18ff0199
1 changed files with 172 additions and 27 deletions
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199
util/grid/grid3.hpp
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@@ -112,6 +112,7 @@ struct Camera {
struct Chunk { struct Chunk {
Voxel reprVoxel; //average of all voxels in chunk for LOD rendering Voxel reprVoxel; //average of all voxels in chunk for LOD rendering
std::vector<bool> activeVoxels; //use this to specify active voxels in this chunk.
//std::vector<Voxel> voxels; //list of all voxels in chunk. //std::vector<Voxel> voxels; //list of all voxels in chunk.
std::vector<Chunk> children; //list of all chunks in chunk std::vector<Chunk> children; //list of all chunks in chunk
bool active; //active if any child chunk or child voxel is active. used to efficiently find active voxels by only going down when an active chunk is found. bool active; //active if any child chunk or child voxel is active. used to efficiently find active voxels by only going down when an active chunk is found.
@@ -125,7 +126,6 @@ private:
Vec3i gridSize; Vec3i gridSize;
std::vector<Voxel> voxels; std::vector<Voxel> voxels;
std::unordered_map<Vec3i, Chunk, Vec3i::Hash> chunkList; std::unordered_map<Vec3i, Chunk, Vec3i::Hash> chunkList;
std::unordered_map<Vec3i, bool, Vec3i::Hash> activeChunks;
int xyPlane; int xyPlane;
float radians(float rads) { float radians(float rads) {
@@ -141,9 +141,138 @@ private:
if (isActive) { if (isActive) {
chunkList[chunkCoord].active = true; chunkList[chunkCoord].active = true;
activeChunks[chunkCoord] = true;
} }
} }
size_t mortonEncode1(int x,int y, int z) const {
//TIME_FUNCTION;
size_t result = 0;
for (int i = 0; i < 21; i++) {
result |= ((x & (1 << i)) << (2 * i)) |
((y & (1 << i)) << (2 * i + 1)) |
((z & (1 << i)) << (2 * i + 2));
}
return result;
}
size_t mortonEncode2(int x,int y, int z) const {
//TIME_FUNCTION;
size_t result = 0;
uint64_t xx = x & 0x1FFFFF; // Mask to 21 bits
uint64_t yy = y & 0x1FFFFF;
uint64_t zz = z & 0x1FFFFF;
// Spread bits using parallel bit deposit operations
xx = (xx | (xx << 32)) & 0x1F00000000FFFF;
xx = (xx | (xx << 16)) & 0x1F0000FF0000FF;
xx = (xx | (xx << 8)) & 0x100F00F00F00F00F;
xx = (xx | (xx << 4)) & 0x10C30C30C30C30C3;
xx = (xx | (xx << 2)) & 0x1249249249249249;
yy = (yy | (yy << 32)) & 0x1F00000000FFFF;
yy = (yy | (yy << 16)) & 0x1F0000FF0000FF;
yy = (yy | (yy << 8)) & 0x100F00F00F00F00F;
yy = (yy | (yy << 4)) & 0x10C30C30C30C30C3;
yy = (yy | (yy << 2)) & 0x1249249249249249;
zz = (zz | (zz << 32)) & 0x1F00000000FFFF;
zz = (zz | (zz << 16)) & 0x1F0000FF0000FF;
zz = (zz | (zz << 8)) & 0x100F00F00F00F00F;
zz = (zz | (zz << 4)) & 0x10C30C30C30C30C3;
zz = (zz | (zz << 2)) & 0x1249249249249249;
result = xx | (yy << 1) | (zz << 2);
return result;
}
size_t mortonEncode3(int x,int y, int z) const {
//TIME_FUNCTION;
size_t result = 0;
uint64_t xx = x & 0x1FFFFF; // 21 bits: 2,097,152 values
uint64_t yy = y & 0x1FFFFF;
uint64_t zz = z & 0x1FFFFF;
// Spread bits using optimized shifts and masks
xx = (xx * 0x100000) & 0xFFC00000000;
xx = (xx * 0x40000) & 0x30000FF0000FF;
xx = (xx * 0x100) & 0x300F00F00F00F00F;
xx = (xx * 0x10) & 0xC30C30C30C30C30C3;
xx = (xx * 0x4) & 0x49249249249249249;
yy = (yy * 0x100000) & 0xFFC00000000;
yy = (yy * 0x40000) & 0x30000FF0000FF;
yy = (yy * 0x100) & 0x300F00F00F00F00F;
yy = (yy * 0x10) & 0xC30C30C30C30C30C3;
yy = (yy * 0x4) & 0x49249249249249249;
zz = (zz * 0x100000) & 0xFFC00000000;
zz = (zz * 0x40000) & 0x30000FF0000FF;
zz = (zz * 0x100) & 0x300F00F00F00F00F;
zz = (zz * 0x10) & 0xC30C30C30C30C30C3;
zz = (zz * 0x4) & 0x49249249249249249;
result = xx | (yy << 1) | (zz << 2);
return result;
}
size_t mortonEncode4(int x,int y, int z) const {
//TIME_FUNCTION;
size_t result = 0;
auto spread21 = [](uint64_t n) -> uint64_t {
n &= 0x1FFFFF; // Keep only 21 bits
n = (n | (n << 32)) & 0x1F00000000FFFF;
n = (n | (n << 16)) & 0x1F0000FF0000FF;
n = (n | (n << 8)) & 0x100F00F00F00F00F;
n = (n | (n << 4)) & 0x10C30C30C30C30C3;
n = (n | (n << 2)) & 0x1249249249249249;
return n;
};
result = spread21(x) | (spread21(y) << 1) | (spread21(z) << 2);
return result;
}
size_t mortonEncode5(int x,int y, int z) const {
//TIME_FUNCTION;
size_t result = 0;
uint64_t xx = x & 0x1FFFFF;
uint64_t yy = y & 0x1FFFFF;
uint64_t zz = z & 0x1FFFFF;
#ifdef __BMI2__
// Use PDEP instruction if available (Intel/AMD CPUs with BMI2)
uint64_t spread_x = _pdep_u64(xx, 0x9249249249249249);
uint64_t spread_y = _pdep_u64(yy, 0x9249249249249249);
uint64_t spread_z = _pdep_u64(zz, 0x9249249249249249);
return spread_x | (spread_y << 1) | (spread_z << 2);
#else
// Fallback to manual bit spreading
auto spread = [](uint64_t n) -> uint64_t {
n = (n | (n << 32)) & 0x1F00000000FFFF;
n = (n | (n << 16)) & 0x1F0000FF0000FF;
n = (n | (n << 8)) & 0x100F00F00F00F00F;
n = (n | (n << 4)) & 0x10C30C30C30C30C3;
n = (n | (n << 2)) & 0x1249249249249249;
return n;
};
return spread(xx) | (spread(yy) << 1) | (spread(zz) << 2);
#endif
return result;
}
size_t mortonEncodefallback(int x,int y, int z) const {
TIME_FUNCTION;
size_t result = 0;
result = z * xyPlane + y * gridSize.x + x;
return result;
}
size_t mortonEncode(int x, int y, int z) const {
size_t result = 0;
// Total (s) Avg (s) Min (s) Median (s) P99 (s) P99.9 (s) Max (s)
//result = mortonEncode1(x,y,z); // (5) 119.849897 23.969979 23.405616 23.535808 25.063036 25.063036 25.063036
result = mortonEncode2(x,y,z); // (5) 51.146427 10.229285 9.930608 10.030483 11.166704 11.166704 11.166704
//result = mortonEncode3(x,y,z); broken
//result = mortonEncode4(x,y,z); // (5) 55.926195 11.185239 10.567710 10.856774 12.258461 12.258461 12.258461
//result = mortonEncode5(x,y,z); // (5) 53.964580 10.792916 10.475732 10.680918 11.422500 11.422500 11.422500
//result = mortonEncodefallback(x,y,z);
//alternative:
//result = z * xyPlane + y * gridSize.x + x;
return result;
}
// Slab method for AABB intersection // Slab method for AABB intersection
bool intersectRayAABB(const Vec3f& origin, const Vec3f& dir, const Vec3f& boxMin, const Vec3f& boxMax, float& tNear, float& tFar) const { bool intersectRayAABB(const Vec3f& origin, const Vec3f& dir, const Vec3f& boxMin, const Vec3f& boxMax, float& tNear, float& tFar) const {
@@ -187,11 +316,11 @@ public:
static std::unique_ptr<VoxelGrid> deserializeFromFile(const std::string& filename); static std::unique_ptr<VoxelGrid> deserializeFromFile(const std::string& filename);
Voxel& get(int x, int y, int z) { Voxel& get(int x, int y, int z) {
return voxels[z * xyPlane + y * gridSize.x + x]; return voxels[mortonEncode(x,y,z)];
} }
const Voxel& get(int x, int y, int z) const { const Voxel& get(int x, int y, int z) const {
return voxels[z * xyPlane + y * gridSize.x + x]; return voxels[mortonEncode(x,y,z)];
} }
Voxel& get(const Vec3i& xyz) { Voxel& get(const Vec3i& xyz) {
@@ -206,7 +335,6 @@ public:
std::vector<Voxel> newVoxels(newW * newH * newD); std::vector<Voxel> newVoxels(newW * newH * newD);
std::unordered_map<Vec3i, Chunk, Vec3i::Hash> chunklist; std::unordered_map<Vec3i, Chunk, Vec3i::Hash> chunklist;
std::unordered_map<Vec3i, bool, Vec3i::Hash> newActiveChunks;
int copyW = std::min(static_cast<int>(gridSize.x), newW); int copyW = std::min(static_cast<int>(gridSize.x), newW);
int copyH = std::min(static_cast<int>(gridSize.y), newH); int copyH = std::min(static_cast<int>(gridSize.y), newH);
@@ -225,13 +353,11 @@ public:
for (int x = 0; x < copyW; ++x) { for (int x = 0; x < copyW; ++x) {
if (voxels[oldRowStart + x].active) { if (voxels[oldRowStart + x].active) {
Vec3i cc(x / CHUNK_THRESHOLD, y / CHUNK_THRESHOLD, z / CHUNK_THRESHOLD); Vec3i cc(x / CHUNK_THRESHOLD, y / CHUNK_THRESHOLD, z / CHUNK_THRESHOLD);
newActiveChunks[cc] = true;
} }
} }
} }
} }
voxels = std::move(newVoxels); voxels = std::move(newVoxels);
activeChunks = std::move(newActiveChunks);
gridSize = Vec3i(newW, newH, newD); gridSize = Vec3i(newW, newH, newD);
xyPlane = gridSize.x * gridSize.y; xyPlane = gridSize.x * gridSize.y;
} }
@@ -283,14 +409,34 @@ public:
return voxl.AllGTE(0) && voxl.AllLT(gridSize); return voxl.AllGTE(0) && voxl.AllLT(gridSize);
} }
void voxelTraverse(const Vec3f& origin, const Vec3f& end, Voxel& outVoxel, Vec3i& step, const Vec3f& ray, Vec3f& tMax, int maxDist = 10000000) const { void voxelTraverse(const Vec3f& origin, const Vec3f& end, Voxel& outVoxel, Vec3i& step, int maxDist = 10000000) const {
Vec3i cv = origin.floorToI(); Vec3i cv = origin.floorToI();
Vec3i lv = end.floorToI(); Vec3i lv = end.floorToI();
Vec3f ray = end - origin;
step = Vec3i(ray.x >= 0 ? 1 : -1, ray.y >= 0 ? 1 : -1, ray.z >= 0 ? 1 : -1); step = Vec3i(ray.x >= 0 ? 1 : -1, ray.y >= 0 ? 1 : -1, ray.z >= 0 ? 1 : -1);
Vec3f tDelta = Vec3f(ray.x != 0 ? std::abs(1.0f / ray.x) : INF, Vec3f tDelta = Vec3f(ray.x != 0 ? std::abs(1.0f / ray.x) : INF,
ray.y != 0 ? std::abs(1.0f / ray.y) : INF, ray.y != 0 ? std::abs(1.0f / ray.y) : INF,
ray.z != 0 ? std::abs(1.0f / ray.z) : INF); ray.z != 0 ? std::abs(1.0f / ray.z) : INF);
Vec3f tMax;
if (ray.x > 0) {
tMax.x = (std::floor(origin.x) + 1.0f - origin.x) / ray.x;
} else if (ray.x < 0) {
tMax.x = (origin.x - std::floor(origin.x)) / -ray.x;
} else tMax.x = INF;
if (ray.y > 0) {
tMax.y = (std::floor(origin.y) + 1.0f - origin.y) / ray.y;
} else if (ray.y < 0) {
tMax.y = (origin.y - std::floor(origin.y)) / -ray.y;
} else tMax.y = INF;
if (ray.z > 0) {
tMax.z = (std::floor(origin.z) + 1.0f - origin.z) / ray.z;
} else if (ray.z < 0) {
tMax.z = (origin.z - std::floor(origin.z)) / -ray.z;
} else tMax.z = INF;
float dist = 0.0f; float dist = 0.0f;
outVoxel.alpha = 0.0; outVoxel.alpha = 0.0;
@@ -373,18 +519,18 @@ public:
precomputedSteps[7] = Vec3i(-1, -1, -1);// --- precomputedSteps[7] = Vec3i(-1, -1, -1);// ---
std::array<Vec3f, 8> precomputedTMax; std::array<Vec3f, 8> precomputedTMax;
Vec3f floored = cam.posfor.origin.floor(); // Vec3f floored = cam.posfor.origin.floor();
Vec3f dNext = floored + 1.f - cam.posfor.origin; // Vec3f dNext = floored + 1.f - cam.posfor.origin;
Vec3f dPrev = cam.posfor.origin - floored; // Vec3f dPrev = cam.posfor.origin - floored;
precomputedTMax[0] = Vec3f(dNext.x, dNext.y, dNext.z); // precomputedTMax[0] = Vec3f(dNext.x, dNext.y, dNext.z);
precomputedTMax[1] = Vec3f(dPrev.x, dNext.y, dNext.z); // precomputedTMax[1] = Vec3f(dPrev.x, dNext.y, dNext.z);
precomputedTMax[2] = Vec3f(dNext.x, dPrev.y, dNext.z); // precomputedTMax[2] = Vec3f(dNext.x, dPrev.y, dNext.z);
precomputedTMax[3] = Vec3f(dPrev.x, dPrev.y, dNext.z); // precomputedTMax[3] = Vec3f(dPrev.x, dPrev.y, dNext.z);
precomputedTMax[4] = Vec3f(dNext.x, dNext.y, dPrev.z); // precomputedTMax[4] = Vec3f(dNext.x, dNext.y, dPrev.z);
precomputedTMax[5] = Vec3f(dPrev.x, dNext.y, dPrev.z); // precomputedTMax[5] = Vec3f(dPrev.x, dNext.y, dPrev.z);
precomputedTMax[6] = Vec3f(dNext.x, dPrev.y, dPrev.z); // precomputedTMax[6] = Vec3f(dNext.x, dPrev.y, dPrev.z);
precomputedTMax[7] = Vec3f(dPrev.x, dPrev.y, dPrev.z); // precomputedTMax[7] = Vec3f(dPrev.x, dPrev.y, dPrev.z);
frame outFrame(resolution.x, resolution.y, colorformat); frame outFrame(resolution.x, resolution.y, colorformat);
std::vector<uint8_t> colorBuffer; std::vector<uint8_t> colorBuffer;
@@ -437,15 +583,15 @@ public:
int xQuad = yQuad; int xQuad = yQuad;
if (u < 0) xQuad ^= 1; if (u < 0) xQuad ^= 1;
step = precomputedSteps[xQuad]; step = precomputedSteps[xQuad];
Vec3f tMaxBase = precomputedTMax[xQuad]; //Vec3f tMaxBase = precomputedTMax[xQuad];
Vec3f ray = rayEnd - rayStartGrid; Vec3f ray = rayEnd - rayStartGrid;
Vec3f tMax( // Vec3f tMax(
ray.x != 0 ? tMaxBase.x / std::abs(ray.x) : INF, // ray.x != 0 ? tMaxBase.x / std::abs(ray.x) : INF,
ray.y != 0 ? tMaxBase.y / std::abs(ray.y) : INF, // ray.y != 0 ? tMaxBase.y / std::abs(ray.y) : INF,
ray.z != 0 ? tMaxBase.z / std::abs(ray.z) : INF // ray.z != 0 ? tMaxBase.z / std::abs(ray.z) : INF
); // );
voxelTraverse(rayStartGrid, rayEnd, outVoxel, step, ray, tMax, maxDist); voxelTraverse(rayStartGrid, rayEnd, outVoxel, step, maxDist);
Vec3ui8 hitColor = outVoxel.color; Vec3ui8 hitColor = outVoxel.color;
// Set pixel color in buffer // Set pixel color in buffer
switch (colorformat) { switch (colorformat) {
@@ -492,7 +638,6 @@ public:
std::cout << "Total voxels: " << totalVoxels << std::endl; std::cout << "Total voxels: " << totalVoxels << std::endl;
std::cout << "Active voxels: " << activeVoxels << std::endl; std::cout << "Active voxels: " << activeVoxels << std::endl;
std::cout << "Inactive voxels: " << (totalVoxels - activeVoxels) << std::endl; std::cout << "Inactive voxels: " << (totalVoxels - activeVoxels) << std::endl;
std::cout << "Active chunks (map size): " << activeChunks.size() << std::endl;
std::cout << "Active percentage: " << activePercentage << "%" << std::endl; std::cout << "Active percentage: " << activePercentage << "%" << std::endl;
std::cout << "Memory usage (approx): " << (voxels.size() * sizeof(Voxel)) / 1024 << " KB" << std::endl; std::cout << "Memory usage (approx): " << (voxels.size() * sizeof(Voxel)) / 1024 << " KB" << std::endl;
std::cout << "============================" << std::endl; std::cout << "============================" << std::endl;