mobilegl-dev/mobilegl/renderdoc-debug-on-trace-replay

Capture a RenderDoc Trace Frame

Use the repository tool to queue TargetControl before launching the replay activity, keep the connection alive until capture completion, pull the RDC, and write a reproducible JSON manifest.

Prepare

1. Work from the MobileGL repository root.
2. Confirm python, adb, apitrace, and rdc are on PATH.
3. Confirm the trace replay APK is installed and debuggable:

adb devices -l
adb -s SERIAL shell pm path top.mobilegl.plugin.trace
rdc doctor

1. Pass the unpacked trace.trace, its golden PNG, the fixture target call, backend, and output path to tools/trace_replay/skills/renderdoc-debug-on-trace-replay/scripts/capture_android_retrace.py.

Capture

Let the tool infer the zero-based target swap from eglSwapBuffers calls:

python tools/trace_replay/skills/renderdoc-debug-on-trace-replay/scripts/capture_android_retrace.py --trace .trace-work/case/trace.trace --golden tools/trace_replay/fixtures/case.0002667619.png --target-call 2667619 --backend DirectVulkan --output captures/case-vulkan.rdc --serial SERIAL --json

Change only the backend and output for GLES:

python tools/trace_replay/skills/renderdoc-debug-on-trace-replay/scripts/capture_android_retrace.py --trace .trace-work/case/trace.trace --golden tools/trace_replay/fixtures/case.0002667619.png --target-call 2667619 --backend DirectGLES --output captures/case-gles.rdc --serial SERIAL --json

Use --target-swap N when the mapping is already known. Use --capture-frame N only to override the backend rule deliberately.

The default mapping is:

• DirectGLES: capture the zero-based target swap.
• DirectVulkan: capture target swap - 1, so the capture closes at the terminal target Present. Queueing the terminal Vulkan swap itself can never finish when the retrace stops immediately after that Present.

The tool applies a 256 MiB RenderDoc softMemoryLimit for Vulkan, installs the GLES layer only for GLES, queues before Activity launch, drains asynchronous TargetControl registration messages, and restores device properties and forwards afterward. Do not replace it with a late rdc script call.

Inspect the Output

Read <output>.rdc.json. Require all of the following:

• success is true.
• capture.frame equals the requested capture frame.
• capture.api matches Vulkan or OpenGLES.
• byteSize is non-zero and sha256 is present.
• retraceResult says the replay completed; treat its SSIM separately from RDC validity.
• commands and commandLines contain the full reproducible command history.

A DirectVulkan SSIM below a GLES golden threshold can be a backend rendering difference. Do not reject the RDC solely for that reason if RenderDoc can replay it and the target render output is present.

Validate with RenderDoc

Validate GLES locally:

rdc close
rdc open captures/case-gles.rdc
rdc info --json
rdc count events
rdc count draws
rdc count passes
rdc assert-clean --min-severity high --json

Validate device-specific Vulkan captures on the original Android GPU:

rdc android setup --json
adb -s SERIAL forward --list
rdc close
rdc open captures/case-vulkan.rdc --proxy 127.0.0.1:FORWARDED_REMOTE_PORT
rdc info --json
rdc count events
rdc count draws
rdc count passes
rdc assert-clean --min-severity high --json

Use the local TCP port mapped to localabstract:renderdoc_39920 as FORWARDED_REMOTE_PORT. Prefer Android remote replay when a desktop GPU lacks the Android capture's memory types.

Diagnose Failures

Read references/android-renderdoc-troubleshooting.md when capture metadata is missing, a capture times out, the GLES layer does not load, Vulkan stalls on initial contents, rdc android setup --serial cannot select a listed device, or desktop replay rejects a Vulkan RDC.