Heads-Up Display (HUD)

The HUD is a heads-up display which overlays directly on your application. You can use the HUD to view real-time GPU signals and performance counters, capture a frame, and scrub through its constituent draw calls.  

All actions that occur either in the HUD, or on the host inside Visual Studio - such as capturing a frame or scrubbing to a specific draw call - are automatically synchronized between the HUD and the host, and thus you can switch between using the HUD and host UI seamlessly as needed.

The HUD has three (3) modes:

Running: Interact with your game or application normally, while the HUD shows real-time GPU performance graphs overlaid on the scene. When you first start your Direct3D application with NVIDIA Nsight, the HUD is in Running mode. This mode is most useful for viewing GPU performance information in real-time while you play your game.

Activated: Once activated (using the activation hot-key toggle), the NVIDIA Nsight HUD allows the resize or repositioning the signal graphs, and the pause and capture of a frame from the running application.

Frame Debugger: Once you have captured a frame, you can debug the frame directly in the NVIDIA Nsight HUD (as well as from the Visual Studio). The HUD allows you to scrub through the constituent draw calls of a Direct3D frame, to view render targets with panning and zooming, and to examine specific values in those render targets.

Running Mode

In this mode, your application can interact with the game or application normally, and the HUD shows real-time GPU performance graphs overlaid on the scene. When you first start your application with NVIDIA Nsight, the HUD is in Running mode.

To activate the HUD:

Make sure your Direct3D application has focus, and then enter the activation hot-key, CTRL+Z. The HUD is now in Activated mode. 

Activated Mode

Once activated (using the activation hot-key toggle), the HUD allows you to resize or reposition the signal graphs, and then pause and capture a frame from the running application. A toolbar containing common operations becomes visible in this mode.

Frame Debugger Mode

Once you have captured a frame, you can debug the frame directly in the HUD. While you can also debug the frame within Visual Studio, the HUD allows you to scrub through the constituent draw calls of a Direct3D frame, to view render targets with panning and zooming, and to examine specific values in those render targets.

To view a particular draw call in your frame:

1. Left-click and drag on the scrub bar at the bottom on the screen. Hold Shift when scrubbing for more scrub precision, which is especially useful when looking at frames with a large number of draw calls.
2. When the desired draw call is active, release the left mouse button. Geometry for the currently active draw call will be highlighted, as long as it is on screen.

To pan and zoom the currently showing render target:

1. Left-click and drag directly on the currently shown render target.
2. Use the mouse wheel to zoom in to a particular portion of the render target.

To see the value under the mouse for currently showing render target:

1. Hold the Control key while you mouse over a render target.
2. A small display window will show you a high-zoom view of the pixels in the area, and the value of the current pixel the mouse is over. 

To save the current frame for later debugging or profiling:

Sometimes starting up the application and getting to a specific spot can take a very long time. Instead, you can save the frame to an .nvframecapture file. The replayer can be debugged using Nsight, and load the file for a much faster startup. Using this method, the capture can also be shared among the development team, to point out any potential errors or problems.

1. Click the Save button on the HUD toolbar.  
   The frame will be saved on disk. You may hit the Escape key at any time to cancel.
2. A .nvframecapture file will be saved in your Documents/NVIDIA Nsight/Captures directory.
3. The saved .nvframecapture file can be replayed at a later time by running it using the Nvda.Replayer.100.exe application located in the Common/Injection directory of your Nsight Monitor installation.

WARNING: Writing the frame to disk may fail, if the system runs out of memory. This is more likely to happen on 32-bit systems where user mode memory is typically limited to 2GB. If you find that writing the frame to disk is failing, try adding more memory, using the 3GB memory switch, or use a 64-bit system.

For more information on using the replayer, see Appendix B: Replayer.

To switch the display to another active render target:

1. Click the Select Render Target button on the HUD toolbar.
2. A drop down menu will appear, showing all valid choices for the current draw call. Select the desired render target.
3. Note that if a selected render target is not still active for a different draw call, the display will automatically switch to an active render target.