Effect shader linking is a Direct2D optimization that links multiple shaders together so that they can be rendered in a single pass. If you're writing custom shaders, you want to ensure that they are linking compatible in order to take advantage of this optimization. The official documentation explains how to author and compile such effects, however the default HLSL build in Visual Studio does not provide support for linking-compatible shaders. Instead, you need to configure a custom build step to do this, which is what this post will walk you through.
Step 1: Create a batch script to compile the shader
First, create a batch script in your Visual Studio project that will execute the two-step process to compile a linking-compatible shader, let's call it buildshader.bat:
fxc %1.hlsl /nologo /T lib_4_0 /D D2D_FUNCTION /D D2D_ENTRY=main /Fl %1.fxlib /I %2
fxc %1.hlsl /nologo /T ps_4_0 /D D2D_FULL_SHADER /D D2D_ENTRY=main /E main /setprivate %1.fxlib /Fo:%1.cso /I %2
This is taken straight from the official documentation, except I've introduced a couple of parameters so it can be used as a custom build tool. The first is the input file and the second is the SDK include directory (which is required for the d2d1effecthelpers include that you will be using in your shader). The outputs of this script are a .fxlib file (intermediate file) and a .cso file (final linking-compatible shader output).
Step 2: Configure a custom build tool for the HLSL file
Next, for each HLSL file in your project, open up the property page and make the following changes:
Item Type
Custom Build Tool
Command Line
buildshader "%(Filename)" "$(UM_IncludePath)"
Outputs
%(Filename).fxlib;%(Filename).cso
Additional Dependencies
buildshader.bat
The outputs and additional dependencies let the build system know when to trigger a rebuild of the input file. You can read more about these options in the Visual Studio documentation.
And that's it! Your shaders will be automatically (re)built as part of the standard Visual Studio build process. If you want to look at an actual example, check out the Fotografix repository on GitHub.
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