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SceneRenderer 实例收集扁平化：batchMats 从 vector<vector> 改为单 vector 按 (first,count) 切片，优化大场景下批次实例存储与 cache 命中率

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atdunbg
2026-10-04 21:26:48 +08:00
parent 3e85285e41
commit e038cb39fa
2 changed files with 43 additions and 30 deletions
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Engine/src/Renderer/SceneRenderer.cpp
+37 -25
View File
@@ -594,7 +594,7 @@ namespace Engine
}
auto tryAppend = [&](ViewScratch& s, const Frustum& frustum,
u32 lod) {
u32 lod) {
if (!frustum.IntersectsSphere(worldCenter, worldRadius)) {
return;
}
@@ -613,16 +613,18 @@ namespace Engine
if (batchIdx == 0) {
batchIdx = static_cast<u32>(s.result.batches.size()) + 1;
lodSlots[lod] = batchIdx;
s.result.batches.push_back({mesh.get(), 0, 0, lod});
s.batchMats.emplace_back();
// first = 当前 instances 数组大小（batch 还没实例）
// push_back 实例后区间自然连续
s.result.batches.push_back(
{mesh.get(), static_cast<u32>(s.instances.size()), 0, lod});
s.batchDistSum.push_back(0.0f);
}
// 实例归入自己的 batch（mesh 分组），保证同 batch
// 实例在扁平化后连续——firstInstance 语义的前提
// 实例在扁平数组里连续——firstInstance 语义的前提
const u32 bi = batchIdx - 1;
s.result.batches[bi].count++;
s.batchMats[bi].push_back(
{t.World(), prevWorld, skinBase, entKey});
s.instances.push_back(
{t.World(), prevWorld, skinBase, entKey}); // 单 vector push
s.batchDistSum[bi] += dist; // 透明排序用
s.result.instanceCount++;
++totalInstances;
@@ -655,10 +657,15 @@ namespace Engine
dst.batches.reserve(s.result.batches.size());
for (size_t i = 0; i < s.result.batches.size(); ++i) {
InstanceBatch b = s.result.batches[i];
// ✅ 保存原 first（s.instances 数组里的下标），b.first 改成
// m_Frame 数组里的基址
const u32 srcFirst = b.first;
b.first = base; // 扁平化后的连续区间基址
base += b.count;
dst.batches.push_back(b);
for (const auto& m : s.batchMats[i]) {
// 按 batch 的 (srcFirst, count) 切片扁平数组
for (u32 j = 0; j < b.count; ++j) {
const auto& m = s.instances[srcFirst + j];
m_Frame.instanceModels.push_back(m.cur);
m_Frame.prevInstanceModels.push_back(m.prev);
// 与实例序平行对齐（shader 按 gl_InstanceIndex 取）
@@ -669,6 +676,7 @@ namespace Engine
}
dst.instanceCount = s.result.instanceCount;
};
appendView(m_Frame.mainView, m_MainScratch);
for (u32 c = 0; c < kMaxCascades; ++c) {
appendView(m_Frame.shadowCascades[c], m_CascScratch[c]);
@@ -681,6 +689,9 @@ namespace Engine
// }
// ---- 5. 透明批次排序：平均距离降序（远 → 近），连同实例列表同步重排
// ---- 5. 透明批次排序：平均距离降序（远 → 近），连同实例列表同步重排。
// 扁平 instances 数组按 order 顺序构建新数组（每个 batch 的
// (first,count) 切片搬过去，新 first = 当前已搬数量）----
{
auto& tb = m_TranslucentScratch.result.batches;
if (tb.size() > 1) {
@@ -690,30 +701,31 @@ namespace Engine
return m_TranslucentScratch.batchDistSum[a] / tb[a].count >
m_TranslucentScratch.batchDistSum[b] / tb[b].count;
});
CullResult sorted;
sorted.instanceCount = m_TranslucentScratch.result.instanceCount;
std::vector<ViewScratch::InstanceMatrices> sortedMats;
// 临时构建（容量保留由 swap 进 m_TranslucentScratch 复用）
std::vector<InstanceBatch> sortedBatches;
std::vector<ViewScratch::InstanceMatrices> sortedInstances;
std::vector<f32> sortedDist;
sortedBatches.reserve(tb.size());
sortedDist.reserve(tb.size());
// 同场景实例总数不变，capacity 可直接复用（reserve 不浪费）
sortedInstances.reserve(m_TranslucentScratch.instances.size());
for (const u32 i : order) {
sorted.batches.push_back(tb[i]);
// 新 batch first = 已搬过去的新 instances 数量
InstanceBatch b = tb[i];
b.first = static_cast<u32>(sortedInstances.size());
sortedBatches.push_back(b);
sortedDist.push_back(m_TranslucentScratch.batchDistSum[i]);
for (auto& m : m_TranslucentScratch.batchMats[i]) {
sortedMats.push_back(std::move(m));
// 按 (原 first, count) 切片搬运原扁平数组
for (u32 j = 0; j < tb[i].count; ++j) {
sortedInstances.push_back(std::move(
m_TranslucentScratch.instances[tb[i].first + j]));
}
}
m_TranslucentScratch.result = std::move(sorted);
m_TranslucentScratch.result.batches = std::move(sortedBatches);
m_TranslucentScratch.batchDistSum = std::move(sortedDist);
// batchMats 按新分组的 count 顺序切分重装（保留容量）
m_TranslucentScratch.batchMats.assign(
m_TranslucentScratch.result.batches.size(), {});
u32 offset = 0;
for (size_t i = 0; i < m_TranslucentScratch.result.batches.size(); ++i) {
const u32 n = m_TranslucentScratch.result.batches[i].count;
m_TranslucentScratch.batchMats[i].assign(
std::make_move_iterator(sortedMats.begin() + offset),
std::make_move_iterator(sortedMats.begin() + offset + n));
offset += n;
}
m_TranslucentScratch.instances = std::move(sortedInstances);
// instanceCount 不变（重排不丢实例）
}
}
appendView(m_Frame.translucentView, m_TranslucentScratch);