XCEngine/tests/Rendering/unit/test_object_id_encoding.cpp

#include <gtest/gtest.h>

#include <XCEngine/Rendering/Picking/ObjectIdCodec.h>

#include <limits>

using namespace XCEngine::Rendering;

TEST(ObjectIdEncoding_Test, ConvertsValidRuntimeObjectIdLosslessly) {
    constexpr uint64_t objectId = 0x00ABCDEFu;
    RenderObjectId renderObjectId = kInvalidRenderObjectId;

    EXPECT_TRUE(CanConvertRuntimeObjectIdToRenderObjectId(objectId));
    EXPECT_TRUE(TryConvertRuntimeObjectIdToRenderObjectId(objectId, renderObjectId));
    EXPECT_EQ(renderObjectId, 0x00ABCDEFu);
    EXPECT_EQ(ConvertRenderObjectIdToRuntimeObjectId(renderObjectId), objectId);
}

TEST(ObjectIdEncoding_Test, RejectsInvalidAndOverflowRuntimeObjectIds) {
    RenderObjectId renderObjectId = 123u;

    EXPECT_FALSE(CanConvertRuntimeObjectIdToRenderObjectId(0u));
    EXPECT_FALSE(TryConvertRuntimeObjectIdToRenderObjectId(0u, renderObjectId));
    EXPECT_EQ(renderObjectId, kInvalidRenderObjectId);

    const uint64_t overflowObjectId =
        static_cast<uint64_t>(std::numeric_limits<RenderObjectId>::max()) + 1ull;
    renderObjectId = 456u;
    EXPECT_FALSE(CanConvertRuntimeObjectIdToRenderObjectId(overflowObjectId));
    EXPECT_FALSE(TryConvertRuntimeObjectIdToRenderObjectId(overflowObjectId, renderObjectId));
    EXPECT_EQ(renderObjectId, kInvalidRenderObjectId);
}

TEST(ObjectIdEncoding_Test, DecodesColorBackToRenderObjectId) {
    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(DecodeRenderObjectIdFromColor(r, g, b, a), 0x78563412u);
    EXPECT_EQ(ConvertRenderObjectIdToRuntimeObjectId(DecodeRenderObjectIdFromColor(r, g, b, a)), 0x78563412ull);
}

TEST(ObjectIdEncoding_Test, EncodesColorChannelsFromRenderObjectId) {
    const auto encodedColor = EncodeRenderObjectIdToColor(0x78563412u);
    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);
}