Using Shaders in Half-Life 2

• Getting Started
• Compiling the Sourcecode
• Installing Necessary Tools
• Compiling the Sample Shaders
• Testing the Sample Shaders
• Editing the Sample Shaders
• Enabling Postprocessing Effects
• Creating Postprocessing Effects
• Creating New Shaders
• Using Textures and Variables
• References

[Perl]\bin\perl.exe   

[mod dir]\src\devtools\bin\ 

[Perl]\bin\perl58.dll 

[mod dir]\src\devtools\bin\ 

[DXSDK]\utilities\fxc.exe 

[mod dir]\src\dx9sdk\utilities\ 

[DXSDK]\utilities\psa.exe 

[mod dir]\src\dx9sdk\utilities\ 

[DXSDK]\utilities\vsa.exe 

[mod dir]\src\dx9sdk\utilities\ 

[Visual Studio]\Vc7\nmake.exe 

[mod dir]\src\sdkshaders\ 

build_sample_shaders.bat -game "[Steam dir]\SteamApps\SourceMods\[mod name]"

[account]\half-life 2\hl2\maps\sdk_shader_samples.bsp   

..\SourceMods\[mod name]\maps\ 

[account]\sourcesdk_content\hl2\mapsrc\sdk_shader_samples.vmf

[mod dir]\mapsrc\ 

[account]\half-life 2\hl2\materials\SDK\sdk_lightmap.vmt

..\SourceMods\[modname]\materials\sdk\ 

[account]\half-life 2\hl2\materials\SDK\sdk_particle.vmt

..\SourceMods\[modname]\materials\sdk\ 

[account]\half-life 2\hl2\materials\SDK\sdk_postprocess.vmt

..\SourceMods\[modname]\materials\sdk\ 

map sdk_shader_samples

return baseColor;

return float4(1.0f, 0.0f, 0.0f, 1.0f);

vOutput.rg = 0.0f;

return vOutput;

The Original Shaders	After Editing...

Enabling Postprocessing Effects
Postprocessing effects are applied to each frame before it is displayed and affect the entire screen. The sample shaders contain a shader that is capable of postprocessing effects, but before it works, you need to modify the sourcecode a bit. Open the file sdk_postprocess.cpp and look for the code that is commented out (right after the #include statements). This code needs to be copied into the mod's source code to enable postprocessing. Open game_sdk.sln in [mod dir]\src and find the file view_scene.cpp (under client->source files). Find the function CViewRender::RenderView(...) and scroll down to the end of the function. Copy the code from sdk_postprocess.cpp to the end of this function right under the command "GenerateOverdrawForTesting();". Build the client and run your mod again. Load any map and watch the result (which should be quite obvious):

The default postprocessing effect (map: dm_lockdown)

Creating Postprocessing Effects
Now that we have a postprocessing shader, we can edit it to apply our own screen filters. This works the same way as editing the other sample shaders: Open the file - Edit the HLSL code - Compile the shader - Run the mod. The files to edit in this case are sdk_postprocess_vs20.fxc and sdk_postprocess_ps20.fxc. The following effects are all accomplished by editing the sdk_postprocess_ps20.fxc file. Click on a screenshot to view the HLSL sourcecode of the fxc file for that effect.

Pure Black & White	Greyscale
Sepia	Thermal

/* Always include this file*/
#include "common_vs_fxc.h"

/* The input of this vertex shader */
struct VS_INPUT
{
	float3 vPos	: POSITION;
};

/* The output of this vertex shader */
struct VS_OUTPUT
{
    	float4 vProjPos : POSITION;	
};

/* main function */
VS_OUTPUT main( const VS_INPUT input )
{
	/* initialize output structure */
	VS_OUTPUT o = ( VS_OUTPUT )0;

	/* Project the point. (multiply with model-view-projection matrix) */
	o.vProjPos = mul( float4( input.vPos, 1 ), cModelViewProj );

	/* Return output */
	return o;
}

/* Always include this file*/
#include "common_ps_fxc.h"

HALF4 main() : COLOR
{	
	/* Output constant green color */
	return float4(0.0f, 1.0f, 0.0f, 1.0f);
}

/* Include important files */
#include "BaseVSShader.h"
#include "convar.h"

// Note: you have to run buildshaders.bat to generate these files from the FXC code.
#include "simpleshader_ps11.inc"
#include "simpleshader_vs11.inc"

/* Start of Shader setup */
BEGIN_VS_SHADER( SimpleShader, "Help for SimpleShader: this shader produces a green color" )

	/* This shader doesn't use parameters*/
	BEGIN_SHADER_PARAMS
	END_SHADER_PARAMS

	// Set up anything that is necessary to make decisions in SHADER_FALLBACK.
	SHADER_INIT_PARAMS()
	{
	}

	/* This is used for providing fallback for lower versions of DirectX */
	SHADER_FALLBACK
	{
		return 0;
	}

	/* Initialize parameters */
	SHADER_INIT
	{
	}

	/* This is where the shader is invoked */
	SHADER_DRAW
	{
		/* Shadow state is executed once per material */
		SHADOW_STATE
		{	
			/* Setup stream format - we only need the position */
			int fmt = VERTEX_POSITION;
			pShaderShadow->VertexShaderVertexFormat( fmt, 0, 0, 0, 0 );

			/* Pick the shaders you want to use */
			simpleshader_vs11_Static_Index vshIndex;
			pShaderShadow->SetVertexShader( "simpleshader_vs11", vshIndex.GetIndex() );

			simpleshader_ps11_Static_Index pshIndex;
			pShaderShadow->SetPixelShader( "simpleshader_ps11", pshIndex.GetIndex() );

			DefaultFog();
		}
		/* Pass dynamic parameters that can change over time */
		DYNAMIC_STATE
		{	
		}

		/* Execute shader */
		Draw();
	}
END_SHADER

"SimpleShader"
{
}

textureshader_vs20.fxc
textureshader_ps20.fxc
textureshader.cpp
textureshader.vmt

/* Always include this file*/
#include "common_vs_fxc.h"

/* Extern variable */
float fSinTime : register (SHADER_SPECIFIC_CONST_0); //read a variable from register location

/* The input of this vertex shader */
struct VS_INPUT
{
	float3 vPos	: POSITION;
	float2 vTexCoord : TEXCOORD0; //read a pair of texture coordinates from the vertex
};

/* The output of this vertex shader */
struct VS_OUTPUT
{
    	float4 vProjPos : POSITION;
	float2 vTexCoord : TEXCOORD0;	 //pass texture coordinates to pixel shader
};

/* main function */
VS_OUTPUT main( const VS_INPUT input )
{
	/* initialize output structure */
	VS_OUTPUT output = ( VS_OUTPUT )0;

	/* Project the point. (multiply with model-view-projection matrix) */
	output.vProjPos = mul( float4( input.vPos, 1 ), cModelViewProj );

	/* Pass texture coordinates to pixel shader */
	output.vTexCoord.x = input.vTexCoord.x + fSinTime; 
	output.vTexCoord.y = input.vTexCoord.y + fSinTime; //offset the texture coordinates using the variable

	/* Return output */
	return output;
}

/* Always include this file*/
#include "common_ps_fxc.h"

/* Get texture */
sampler BaseTexture : register ( s0 ); //read texture from register location

HALF4 main(float2 TexCoord : TEXCOORD0) : COLOR //takes texture coordinates as input
{	
	/* Output texture color */
	return tex2D(BaseTexture, TexCoord); //return texel at tex coordinates location
}

LoadTexture( BASETEXTURE );

pShaderShadow->EnableTexture( SHADER_TEXTURE_STAGE0, true );
		
int fmt = VERTEX_POSITION;
pShaderShadow->VertexShaderVertexFormat( fmt, 1, 0, 0, 0 );

BindTexture( SHADER_TEXTURE_STAGE0, BASETEXTURE, FRAME );

float sin_time;

sin_time = sin((timeGetTime()/1000.0f));
pShaderAPI->SetVertexShaderConstant( VERTEX_SHADER_SHADER_SPECIFIC_CONST_0, &sin_time );

"TextureShader"
{
	$baseTexture "brick/brickwall045a"
}