Add --no-interop parameter to disable CUDA-OpenGL interoperability #339

Copilot · 2026-01-03T11:38:35Z

Add noInterop setting to GlobalSettings (defaults to true)
Parse --interop command line argument in GUI Main.cpp (enables interop mode)
Modify CudaGeometryBuffers to support non-interop mode with CPU/GPU memory transfers
Modify GeometryKernelsService::extractObjectData to handle both interop and non-interop modes (no separate method)
Simplify SimulationCudaFacade::copyBuffersFromCudaToOpenGL - delegate buffer details to CudaGeometryBuffers
Update _GeometryBuffers class to support uploading from host memory
Add GeometryTests for getNumRenderObjects and tryCopyBuffersFromCudaToOpenGL (no-interop mode only)
Build and test the changes

Usage

Default: ./alien (runs in no-interop mode, uses CPU-GPU memory transfers)
Enable interop: ./alien --interop (uses CUDA-OpenGL interop for rendering)

Original prompt

Implement the following extension: if alien is executed with --no-interop parameter, no cuda-opengl-interop api should be called. instead the memory should be copied between cou and gpu.

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When the --no-interop flag is provided to the ALIEN GUI: - CUDA-OpenGL interop API calls are bypassed - Rendering data is copied from GPU to CPU using cudaMemcpy - CPU-side data is uploaded to OpenGL buffers via glBufferSubData This is useful for systems where CUDA-OpenGL interop doesn't work. Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

chrxh · 2026-01-03T12:26:07Z

source/EngineGpuKernels/SimulationCudaFacade.cu

+        syncAndCheck();
+
+        // Copy from device to host and upload to OpenGL
+        if (numRenderObjects.cells > 0) {


@copilot hide all these details here about the concrete buffers away from SimulationCudaFacade. Maybe CudaGeometryBuffers is a better place for this.

Refactored in dab791d. Moved all buffer copying logic to CudaGeometryBuffers::copyToOpenGL() method. SimulationCudaFacade::copyBuffersFromCudaToOpenGL() now just calls _cudaGeometryBuffers->copyToOpenGL(geometryBuffers, numRenderObjects).

chrxh · 2026-01-03T12:29:47Z

source/EngineGpuKernels/GeometryKernelsService.cuh

    void restorePositions(SettingsForSimulation const& settings, SimulationData data);
    NumRenderObjects getNumRenderObjects(SettingsForSimulation const& settings, SimulationData data, RealRect const& visibleWorldRect);
    void extractObjectData(SettingsForSimulation const& settings, SimulationData data, CudaGeometryBuffers& renderingData, RealRect const& visibleWorldRect);
+    void extractObjectDataNoInterop(SettingsForSimulation const& settings, SimulationData data, CudaGeometryBuffers& renderingData, RealRect const& visibleWorldRect);


@copilot do not add an extra method for the non interop case. extractObjectData should handle this.

Fixed in dab791d. Removed extractObjectDataNoInterop - extractObjectData now handles both interop and non-interop modes internally by checking GlobalSettings::get().isNoInterop().

… merge extractObjectData methods - Removed extractObjectDataNoInterop from GeometryKernelsService - extractObjectData now handles both interop and non-interop modes internally - Added copyToOpenGL method to CudaGeometryBuffers for CPU-GPU-OpenGL transfer - Simplified SimulationCudaFacade::copyBuffersFromCudaToOpenGL to delegate to CudaGeometryBuffers Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

chrxh · 2026-01-03T14:59:56Z

@copilot write parameterized tests for GeometryKernelsService with and without interop. For this, add the new test class GeometryTests. Make minimal usages of comments (only when necessary for the understanding).

- Added GeometryTests.cpp with parameterized tests that run with both interop modes - Added testOnly_getNumRenderObjects method to SimulationFacade interface - Tests verify render object counting works consistently in both modes Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

Copilot · 2026-01-03T15:26:42Z

@copilot write parameterized tests for GeometryKernelsService with and without interop. For this, add the new test class GeometryTests. Make minimal usages of comments (only when necessary for the und...

Added in c38c52f. Created GeometryTests class with parameterized tests for both interop modes (false and true). The tests verify getNumRenderObjects functionality with cells, particles, connections, and creatures. Added testOnly_getNumRenderObjects method to the facade interface for test access.

chrxh · 2026-01-04T21:04:58Z

source/EngineTests/GeometryTests.cpp

+
+INSTANTIATE_TEST_SUITE_P(InteropModes, GeometryTests, ::testing::Values(false, true));
+
+TEST_P(GeometryTests, getNumRenderObjects_emptySim)


@copilot getNumRenderObjects does not depend on the flag non-interop. Here one does not need parameterized tests.
Add also tests for _SimulationFacade::tryCopyBuffersFromCudaToOpenGL. Here the parameterization is necessary.

Fixed in 87001de. Removed parameterization from getNumRenderObjects tests (now TEST_F). Added GeometryTests_CopyBuffers class with parameterized tests for tryCopyBuffersFromCudaToOpenGL. Interop mode tests (/0) skip when CUDA-OpenGL interop is unavailable; no-interop mode tests (/1) run and pass.

…ameterized copyBuffers - Removed parameterization from getNumRenderObjects tests (not interop-dependent) - Added parameterized tests for tryCopyBuffersFromCudaToOpenGL with interop modes - Tests with interop mode skip gracefully when CUDA-OpenGL interop is unavailable - Tests with no-interop mode (GetParam()=true) run and pass Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

chrxh · 2026-01-04T21:37:17Z

@copilot make all GeometryTests for no-interop mode (i.e. remove parameterization) since openGL context is not available in test environment.

- Merged GeometryTests and GeometryTests_CopyBuffers into single GeometryTests class - All tests now run in no-interop mode (GlobalSettings::get().setNoInterop(true)) - Removed parameterization since OpenGL context is not available in test environment Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

Copilot · 2026-01-04T21:50:06Z

@copilot make all GeometryTests for no-interop mode (i.e. remove parameterization) since openGL context is not available in test environment.

Fixed in b183260. Simplified GeometryTests to use no-interop mode only - removed parameterization and merged both test classes. All 15 tests now run in no-interop mode with GlobalSettings::get().setNoInterop(true).

chrxh · 2026-01-05T08:07:22Z

@copilot alien should be started with non interop mode by default. Change the CLI parameter --no-interop to --interop such that the user must explicitly set interop mode.

- Default to no-interop mode (noInterop = true) - Changed CLI parameter from --no-interop to --interop - User must now explicitly pass --interop to enable CUDA-OpenGL interop Co-authored-by: chrxh <73127001+chrxh@users.noreply.github.com>

Copilot · 2026-01-05T08:19:09Z

@copilot alien should be started with non interop mode by default. Change the CLI parameter --no-interop to --interop such that the user must explicitly set interop mode.

Done in c9c3aa2. Changed default to no-interop mode and renamed CLI parameter from --no-interop to --interop. User must now explicitly pass --interop to enable CUDA-OpenGL interop mode.

Initial plan

0621309

Copilot AI assigned Copilot and chrxh Jan 3, 2026

Copilot started work on behalf of chrxh January 3, 2026 11:40 View session

Copilot AI changed the title ~~[WIP] Add handling for --no-interop parameter in alien~~ Add --no-interop parameter to disable CUDA-OpenGL interoperability Jan 3, 2026

Copilot AI requested a review from chrxh January 3, 2026 12:11

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chrxh reviewed Jan 3, 2026

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Copilot finished work on behalf of chrxh January 3, 2026 15:28

Code simplified

530a430

chrxh reviewed Jan 4, 2026

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Copilot started work on behalf of chrxh January 4, 2026 21:38 View session

Copilot finished work on behalf of chrxh January 4, 2026 21:51

Fix crash in MainLoopController

c842ad9

Copilot started work on behalf of chrxh January 5, 2026 08:08 View session

Copilot finished work on behalf of chrxh January 5, 2026 08:19

Renamings

0713e27

chrxh marked this pull request as ready for review January 5, 2026 08:43

chrxh merged commit 12f20b8 into develop Jan 5, 2026
1 check failed

chrxh deleted the copilot/add-no-interop-parameter-handling branch January 5, 2026 08:43


		INSTANTIATE_TEST_SUITE_P(InteropModes, GeometryTests, ::testing::Values(false, true));

		TEST_P(GeometryTests, getNumRenderObjects_emptySim)

Add --no-interop parameter to disable CUDA-OpenGL interoperability #339

Add --no-interop parameter to disable CUDA-OpenGL interoperability #339

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