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Renderdoc

Renderdoc is a widely used open source GPU debugger. Blender has several options to benefit using renderdoc for debugging.

Renderdoc capturing requires compiling Blender with WITH_RENDERDOC=On and launching Blender with the --debug-gpu-renderdoc command line parameter.

Frame Capturing

  1. Launch Blender from Renderdoc using the --debug-gpu-renderdoc command line parameter.
  2. Press the Play Animation button to ensure the viewport is being rendered constantly.
  3. Press the PrintScreen key to capture a frame.

renderdoc-launch-settings.png

Triggering captures from code

You can also start and stop a renderdoc capture from within Blenders' source code.

  1. Add GPU_debug_capture_begin/GPU_debug_capture_end around the code you want to capture.
  2. Launch Blender from Renderdoc using the --debug-gpu-renderdoc command line parameter.
  3. Every time the GPU_debug_capture_begin/end pair is reached it will automatically record a capture.

Example

In view3d_draw_view the viewport drawing events can be captured by surrounding DRW_draw_view with the GPU_debug_capture_begin/end function calls.

GPU_debug_capture_begin(__func__);
DRW_draw_view(C);
GPU_debug_capture_end();

Note

it is not allowed to land calls to GPU_debug_capture_begin/end in main as they are considered to be debug code.

Command grouping

With the command line parameter --debug-gpu blender will add meta-data to the buffers and commands. This makes it easier to navigate complex frame captures. Command grouping is automatically enabled when running with the --debug-gpu-renderdoc option.

With the command GPU_debug_group_begin(const char * name) a new group can be added. All groups must be closed by calling GPU_debug_group_end(). Many areas already have these debug groups defined.

OpenGL Unused Resource Renderdoc Bug

Most of the time, RenderDoc doesn't identify used resources (SSBOs, Images) and mark them as unused, hiding them from the shader resource lists. This can be worked around by enabling the Show Unusued Items option.

Limitations Renderdoc, Blender & Vulkan

There are some limitations when using Renderdoc to debug the Vulkan backend of Blender.

Dynamic rendering unused attachments

Renderdoc doesn't support VK_EXT_dynamic_rendering_unused_attachments. When running on a platform that does support unused platforms the actual commands may differ. Unused attachments will generate less pipelines.

Wayland

Renderdoc has issues running wayland and vulkan. When using the Vulkan backend it is best to disable wayland. WITH_GHOST_WAYLAND=Off