Shader Debugger

The NVIDIA Nsight Shader Debugger tools allow you to perform source-level debugging of various HLSL shader types. 

You cannot debug a shader with a local debugging configuration; you must configure your system for remote debugging.

To access the Shader Debugger:

1. Start debugging your graphics project.
2. From the Nsight menu, select Shaders List, which will cause the Shaders window to open in Visual Studio. (The window opens automatically if you opened it in a previous debug session.)
   
   
   
   

   The following table shows the possible states of the Symbolics Status:

   Status	Meaning
   Ready	The shader can be debugged.
   Shader has not yet been used by the application	The shader is created, but it has not been used by the application. That means that it cannot yet be debugged.
   No symbols have been loaded for this shader	The shader cannot yet be debugged. This usually happens during startup when the debugger is still loading a defined shader, but has not yet loaded the debug symbolics required for debugging.
   Not a debuggable shader	The shader cannot be debugged. The shader was likely submitted as a binary shader compiled without debug information, which means that the instructions being executed cannot be mapped to the original HLSL source code.

3. To see the source code of a specific shader, double-click on a row in the Shaders window. The document window opens, showing the corresponding source code.
   
   
   
4. From the Nsight menu, select Windows >Graphics Debug Focus.
   
   
    
   The Graphics Focus Picker window displays which shader has focus. The information that you see in Visual Studio corresponds to the shader that has focus. The execution of the target application must be paused in order to see information about a specific shader.

How to Submit Shaders to Enable Debugging

In order to debug shaders and use the Pixel History functionality, NVIDIA Nsight needs access to the original HLSL source code of your shaders. There are a few ways to accomplish this task. The first is to submit the HLSL source at startup time and compile your shaders, using D3DXCompileShader, D3DX10CompileFromFile, etc. NVIDIA Nsight can intercept these calls to gain access to the HLSL source code and display it for debugging.

Alternatively, you can precompile the shaders into binary format using the same functions and saving the results out to a file, or use the offline compiler, fxc.exe, provided by the DirectX SDK. However, using this method, you need to specify some flags in order for the HLSL debug information to be embedded in the binary output, outlined below: 

D3DXCompileShader	Compiler Flag (using fxc.exe)
D3DXSHADER_PREFER_FLOW_CONTROL	/Gfp
D3DXSHADER_DEBUG	/Zi
D3DXSHADER_SKIPOPTIMIZATION	/Od