refactor: extract viewport object id picker

tests/editor/CMakeLists.txt

@@ -11,6 +11,7 @@ set(EDITOR_TEST_SOURCES
     test_scene_viewport_picker.cpp
     test_scene_viewport_overlay_renderer.cpp
     test_viewport_host_surface_utils.cpp
+    test_viewport_object_id_picker.cpp
     test_builtin_icon_layout_utils.cpp
     ${CMAKE_SOURCE_DIR}/editor/src/Core/UndoManager.cpp
     ${CMAKE_SOURCE_DIR}/editor/src/Managers/SceneManager.cpp

tests/editor/test_viewport_object_id_picker.cpp

@@ -0,0 +1,115 @@
+#include <gtest/gtest.h>
+
+#include "Viewport/ViewportObjectIdPicker.h"
+
+#include <cstdint>
+
+namespace {
+
+using XCEngine::Editor::BuildViewportObjectIdReadbackRequest;
+using XCEngine::Editor::CanPickViewportObjectId;
+using XCEngine::Editor::TryPickViewportObjectIdEntity;
+using XCEngine::Editor::ViewportObjectIdPickContext;
+using XCEngine::Editor::ViewportObjectIdReadbackRequest;
+using XCEngine::RHI::RHICommandQueue;
+using XCEngine::RHI::RHITexture;
+using XCEngine::RHI::ResourceStates;
+
+RHICommandQueue* MakeDummyQueue() {
+    return reinterpret_cast<RHICommandQueue*>(static_cast<uintptr_t>(0x1));
+}
+
+RHITexture* MakeDummyTexture() {
+    return reinterpret_cast<RHITexture*>(static_cast<uintptr_t>(0x2));
+}
+
+ViewportObjectIdPickContext CreateValidContext() {
+    ViewportObjectIdPickContext context = {};
+    context.commandQueue = MakeDummyQueue();
+    context.texture = MakeDummyTexture();
+    context.textureState = ResourceStates::PixelShaderResource;
+    context.textureWidth = 1280;
+    context.textureHeight = 720;
+    context.hasValidFrame = true;
+    context.viewportSize = ImVec2(1280.0f, 720.0f);
+    context.viewportMousePosition = ImVec2(640.0f, 360.0f);
+    return context;
+}
+
+TEST(ViewportObjectIdPickerTest, CanPickRejectsMissingOrOutOfBoundsInputs) {
+    ViewportObjectIdPickContext context = CreateValidContext();
+    EXPECT_TRUE(CanPickViewportObjectId(context));
+
+    context.commandQueue = nullptr;
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+
+    context = CreateValidContext();
+    context.texture = nullptr;
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+
+    context = CreateValidContext();
+    context.hasValidFrame = false;
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+
+    context = CreateValidContext();
+    context.textureWidth = 0;
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+
+    context = CreateValidContext();
+    context.viewportMousePosition = ImVec2(-1.0f, 10.0f);
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+
+    context = CreateValidContext();
+    context.viewportMousePosition = ImVec2(10.0f, 721.0f);
+    EXPECT_FALSE(CanPickViewportObjectId(context));
+}
+
+TEST(ViewportObjectIdPickerTest, BuildReadbackRequestMapsViewportCoordinatesToTexturePixels) {
+    ViewportObjectIdPickContext context = CreateValidContext();
+    context.viewportMousePosition = ImVec2(1280.0f, 720.0f);
+
+    ViewportObjectIdReadbackRequest request = {};
+    ASSERT_TRUE(BuildViewportObjectIdReadbackRequest(context, request));
+    EXPECT_EQ(request.commandQueue, context.commandQueue);
+    EXPECT_EQ(request.texture, context.texture);
+    EXPECT_EQ(request.textureState, ResourceStates::PixelShaderResource);
+    EXPECT_EQ(request.pixelX, 1279u);
+    EXPECT_EQ(request.pixelY, 719u);
+}
+
+TEST(ViewportObjectIdPickerTest, TryPickViewportObjectIdEntityDecodesReadbackColor) {
+    const ViewportObjectIdPickContext context = CreateValidContext();
+
+    uint64_t entityId = 0;
+    ViewportObjectIdReadbackRequest capturedRequest = {};
+    const bool picked = TryPickViewportObjectIdEntity(
+        context,
+        [&capturedRequest](const ViewportObjectIdReadbackRequest& request, std::array<uint8_t, 4>& outRgba) {
+            capturedRequest = request;
+            outRgba = { 0x78, 0x56, 0x34, 0x12 };
+            return true;
+        },
+        entityId);
+
+    EXPECT_TRUE(picked);
+    EXPECT_EQ(entityId, 0x12345678ull);
+    EXPECT_EQ(capturedRequest.pixelX, 640u);
+    EXPECT_EQ(capturedRequest.pixelY, 360u);
+}
+
+TEST(ViewportObjectIdPickerTest, TryPickViewportObjectIdEntityFailsWhenReadbackFails) {
+    const ViewportObjectIdPickContext context = CreateValidContext();
+
+    uint64_t entityId = 99;
+    const bool picked = TryPickViewportObjectIdEntity(
+        context,
+        [](const ViewportObjectIdReadbackRequest&, std::array<uint8_t, 4>&) {
+            return false;
+        },
+        entityId);
+
+    EXPECT_FALSE(picked);
+    EXPECT_EQ(entityId, 0u);
+}
+
+} // namespace