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Formalize object id encoding contract

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This commit is contained in:
ssdfasd
2026-04-05 19:10:31 +08:00
parent 081773b8c9
commit dabd4dd8b2
3 changed files with 68 additions and 13 deletions
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45
engine/include/XCEngine/Rendering/ObjectIdEncoding.h
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@@ -1,18 +1,29 @@
#pragma once
#include <XCEngine/Core/Types.h>
#include <XCEngine/Core/Math/Vector4.h>
#include <cstdint>
namespace XCEngine {
namespace Rendering {
inline uint32_t EncodeObjectIdToUInt32(uint64_t objectId) {
return static_cast<uint32_t>(objectId & 0xFFFFFFFFull);
using EncodedObjectId = Core::uint32;
// Object-id render targets store only the low 32 bits of a runtime object id.
// This codec is for editor/runtime picking surfaces, not for persistent ids.
inline bool CanEncodeObjectIdWithoutLoss(Core::uint64 objectId) {
return (objectId & 0xFFFFFFFF00000000ull) == 0ull;
}
inline Math::Vector4 EncodeObjectIdToColor(uint64_t objectId) {
const uint32_t encodedId = EncodeObjectIdToUInt32(objectId);
inline EncodedObjectId EncodeObjectIdToEncodedId(Core::uint64 objectId) {
return static_cast<EncodedObjectId>(objectId & 0xFFFFFFFFull);
}
inline EncodedObjectId EncodeObjectIdToUInt32(Core::uint64 objectId) {
return EncodeObjectIdToEncodedId(objectId);
}
inline Math::Vector4 EncodeObjectIdToColor(Core::uint64 objectId) {
const EncodedObjectId encodedId = EncodeObjectIdToEncodedId(objectId);
constexpr float kInv255 = 1.0f / 255.0f;
return Math::Vector4(
static_cast<float>((encodedId >> 0) & 0xFFu) * kInv255,
@@ -21,11 +32,23 @@ inline Math::Vector4 EncodeObjectIdToColor(uint64_t objectId) {
static_cast<float>((encodedId >> 24) & 0xFFu) * kInv255);
}
inline uint32_t DecodeObjectIdFromColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
return static_cast<uint32_t>(r) |
(static_cast<uint32_t>(g) << 8u) |
(static_cast<uint32_t>(b) << 16u) |
(static_cast<uint32_t>(a) << 24u);
inline EncodedObjectId DecodeEncodedObjectIdFromColor(
Core::uint8 r,
Core::uint8 g,
Core::uint8 b,
Core::uint8 a) {
return static_cast<EncodedObjectId>(r) |
(static_cast<EncodedObjectId>(g) << 8u) |
(static_cast<EncodedObjectId>(b) << 16u) |
(static_cast<EncodedObjectId>(a) << 24u);
}
inline Core::uint64 DecodeObjectIdFromColor(
Core::uint8 r,
Core::uint8 g,
Core::uint8 b,
Core::uint8 a) {
return static_cast<Core::uint64>(DecodeEncodedObjectIdFromColor(r, g, b, a));
}
} // namespace Rendering

3
tests/Rendering/unit/CMakeLists.txt
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@@ -4,9 +4,8 @@ project(XCEngine_RenderingUnitTests)
set(RENDERING_UNIT_TEST_SOURCES
test_render_pass.cpp
test_object_id_encoding.cpp
test_builtin_forward_pipeline.cpp
test_builtin_post_process_pass_plan.cpp
test_builtin_post_process_pass_sequence_builder.cpp
test_camera_scene_renderer.cpp
test_scene_render_request_planner.cpp
test_scene_render_request_utils.cpp

33
tests/Rendering/unit/test_object_id_encoding.cpp Normal file
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@@ -0,0 +1,33 @@
#include <gtest/gtest.h>
#include <XCEngine/Rendering/ObjectIdEncoding.h>
using namespace XCEngine::Rendering;
TEST(ObjectIdEncoding_Test, EncodesOnlyLow32BitsIntoPickingId) {
constexpr uint64_t objectId = 0x123456789ABCDEF0ull;
EXPECT_FALSE(CanEncodeObjectIdWithoutLoss(objectId));
EXPECT_EQ(EncodeObjectIdToEncodedId(objectId), 0x9ABCDEF0u);
EXPECT_EQ(EncodeObjectIdToUInt32(objectId), 0x9ABCDEF0u);
}
TEST(ObjectIdEncoding_Test, DecodesColorBackToWidenedRuntimeId) {
constexpr uint8_t r = 0x12u;
constexpr uint8_t g = 0x34u;
constexpr uint8_t b = 0x56u;
constexpr uint8_t a = 0x78u;
EXPECT_EQ(DecodeEncodedObjectIdFromColor(r, g, b, a), 0x78563412u);
EXPECT_EQ(DecodeObjectIdFromColor(r, g, b, a), 0x78563412ull);
}
TEST(ObjectIdEncoding_Test, EncodesColorChannelsFromLow32Bits) {
const auto encodedColor = EncodeObjectIdToColor(0x78563412ull);
constexpr float kInv255 = 1.0f / 255.0f;
EXPECT_FLOAT_EQ(encodedColor.x, 0x12u * kInv255);
EXPECT_FLOAT_EQ(encodedColor.y, 0x34u * kInv255);
EXPECT_FLOAT_EQ(encodedColor.z, 0x56u * kInv255);
EXPECT_FLOAT_EQ(encodedColor.w, 0x78u * kInv255);
}