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ReShade FX shading language

Contents

Concepts

The ReShade FX shading language is heavily based on the DX9-style HLSL syntax, with a few extensions. For more details on HLSL, check out the Programming Guide: https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-writing-shaders-9.\ This document will instead primarily focus on syntax and features that are unique to ReShade FX.

Macros

The ReShade FX compiler predefines certain preprocessor macros, as listed below:

  • __FILE__ Current file path
  • __FILE_NAME__ Current file name without path
  • __FILE_STEM__ Current file name without extension and path
  • __LINE__ Current line number
  • __RESHADE__ Version of the injector (in the format MAJOR * 10000 + MINOR * 100 + REVISION)
  • __APPLICATION__ 32-bit truncated Fnv1a hash of the application executable name
  • __VENDOR__ Vendor id (e.g. 0x10de for NVIDIA, 0x1002 for AMD)
  • __DEVICE__ Device id
  • __RENDERER__ Graphics API used to render effects
    • D3D9: 0x9000
    • D3D10: 0xa000 or higher
    • D3D11: 0xb000 or higher (e.g. 0xb100 for D3D11.1)
    • D3D12: 0xc000 or higher
    • OpenGL: 0x10000 or higher (e.g. 0x14300 for OpenGL 4.3)
    • Vulkan: 0x20000 or higher (e.g. 0x21100 for Vulkan 1.1)
  • BUFFER_WIDTH Backbuffer width (essentially the width of the image the application renders to the screen)
  • BUFFER_HEIGHT Backbuffer height
  • BUFFER_RCP_WIDTH Reciprocal of the backbuffer width (equals 1.0 / BUFFER_WIDTH)
  • BUFFER_RCP_HEIGHT Reciprocal of the backbuffer height (equals 1.0 / BUFFER_HEIGHT)
  • BUFFER_COLOR_BIT_DEPTH Color bit depth of the backbuffer (8 or 10)

Constructs like the following may be interpreted as a configurable UI option. To prevent this, the preprocessor define name can be prefixed with an underscore or made shorter or equal to 10 characters, in which case ReShade will not display it in the UI.

#ifndef MY_PREPROCESSOR_DEFINE
	#define MY_PREPROCESSOR_DEFINE 0
#endif

Texture Object

Textures are multidimensional data containers usually used to store images.

Annotations:

  • texture2D imageTex < source = "path/to/image.bmp"; > { ... };
    Opens image from the patch specified, resizes it to the texture size and loads it into the texture.
    ReShade supports Bitmap (*.bmp), Portable Network Graphics (*.png), JPEG (*.jpg), Targa Image (*.tga) and DirectDraw Surface (*.dds) files.

  • texture2D myTex1 < pooled = true; > { Width = 100; Height = 100; Format = RGBA8; };
    texture2D myTex2 < pooled = true; > { Width = 100; Height = 100; Format = RGBA8; };
    ReShade will attempt to re-use the same memory for textures with the same dimensions and format if the pooled annotation is set. This works across effect files too.

ReShade FX allows semantics to be used on texture declarations. This is used to request special textures:

  • texture2D texColor : COLOR;
    Receives the backbuffer contents (read-only).
  • texture2D texDepth : DEPTH;
    Receives the game's depth information (read-only).

Declared textures are created at runtime with the parameters specified in their definition body.

texture2D texColorBuffer : COLOR;
texture2D texDepthBuffer : DEPTH;

texture2D texTarget
{
	// The texture dimensions (default: 1x1).
	Width = BUFFER_WIDTH / 2;
	Height = BUFFER_HEIGHT / 2;
	
	// The number of mipmaps including the base level (default: 1).
	MipLevels = 1;
	
	// The internal texture format (default: RGBA8).
	// Available formats:
	//   R8, R16F, R32F
	//   RG8, RG16, RG16F, RG32F
	//   RGBA8, RGBA16, RGBA16F, RGBA32F
	//   RGB10A2
	Format = RGBA8;

	// Unspecified properties are set to the defaults shown here.
};

Sampler Object

Samplers are the bridge between textures and shaders. They define how a texture is read from and how data outside texel coordinates is sampled. Multiple samplers can refer to the same texture using different options.

sampler2D samplerColor
{
	// The texture to be used for sampling.
	Texture = texColorBuffer;

	// The method used for resolving texture coordinates which are out of bounds.
	// Available values: CLAMP, MIRROR, WRAP or REPEAT, BORDER
	AddressU = CLAMP;
	AddressV = CLAMP;
	AddressW = CLAMP;

	// The magnification, minification and mipmap filtering types.
	// Available values: POINT, LINEAR
	MagFilter = LINEAR;
	MinFilter = LINEAR;
	MipFilter = LINEAR;

	// The maximum mipmap levels accessible.
	MinLOD = 0.0f;
	MaxLOD = 1000.0f;

	// An offset applied to the calculated mipmap level (default: 0).
	MipLODBias = 0.0f;

	// Enable or disable converting  to linear colors when sampling from the
	// texture.
	SRGBTexture = false;

	// Unspecified properties are set to the defaults shown here.
};

sampler2D samplerDepth
{
	Texture = texDepthBuffer;
};
sampler2D samplerTarget
{
	Texture = texTarget;
};

Storage Object

Storage objects define how a texture should be written to from compute shaders.

storage2D storageTarget
{
	// The texture to be used as storage.
	Texture = texTarget;
};

Uniform Variables

Global variables with the uniform qualifier are constant across each iteration of a shader per pass and may be controlled via the UI.

Annotations to customize UI appearance:

  • ui_type: Can be input, drag, slider, combo, radio or color
  • ui_min: The smallest value allowed in this variable (required when ui_type = "drag" or ui_type = "slider")
  • ui_max: The largest value allowed in this variable (required when ui_type = "drag" or ui_type = "slider")
  • ui_step: The value added/subtracted when clicking the button next to the slider
  • ui_items: A list of items for the combo box or radio buttons, each item is terminated with a \0 character (required when ui_type = "combo" or ui_type = "radio")
  • ui_label: Display name of the variable in the UI. If this is missing, the variable name is used instead.
  • ui_tooltip: Text that is displayed when the user hovers over the variable in the UI. Use this for a description.
  • ui_category: Groups values together under a common headline. Note that all variables in the same category also have to be declared next to each other for this to be displayed correctly.
  • ui_category_closed: Set to true to show a category closed by default.
  • ui_spacing: Adds space before the UI widget (multiplied by the value of the annotation).

Annotations are also used to request special runtime values (via the source annotation):

  • uniform float frametime < source = "frametime"; >;
    Time in milliseconds it took for the last frame to complete.
  • uniform int framecount < source = "framecount"; >;
    Total amount of frames since the game started.
  • uniform float4 date < source = "date"; >;
    float4(year, month (1 - 12), day of month (1 - 31), time in seconds)
  • uniform float timer < source = "timer"; >;
    Timer counting time in milliseconds since game start.
  • uniform float2 pingpong < source = "pingpong"; min = 0; max = 9; step = 1; >;
    Counter that counts up and down between min and max using step as increase value. The second component is either +1 or -1 depending on the direction it currently goes.
  • uniform int random_value < source = "random"; min = 0; max = 10; >;
    Gets a new random value between min and max every pass.
  • uniform bool space_bar_down < source = "key"; keycode = 0x20; mode = ""; >;
    True if specified keycode (in this case the spacebar) is pressed and false otherwise. If mode is set to "press" the value is true only in the frame the key was initially held down. If mode is set to "toggle" the value stays true until the key is pressed a second time.
  • uniform bool left_mouse_button_down < source = "mousebutton"; keycode = 0; mode = ""; >;
    True if specified mouse button (0 - 4) is pressed and false otherwise. If mode is set to "press" the value is true only in the frame the key was initially held down. If mode is set to "toggle" the value stays true until the key is pressed a second time.
  • uniform float2 mouse_point < source = "mousepoint"; >;
    Gets the position of the mouse cursor in screen coordinates.
  • uniform float2 mouse_delta < source = "mousedelta"; >;
    Gets the movement of the mouse cursor in screen coordinates.
  • uniform bool has_depth < source = "bufready_depth"; >; True if the application's depth buffer is available in textures declared with DEPTH, false if not.
  • uniform bool overlay_open < source = "overlay_open"; >; True if the ReShade in-game overlay is currently open, false if not.
// Initializers are used to specify the default value (zero is used if not specified).
uniform float4 UniformSingleValue = float4(0.0f, 0.0f, 0.0f, 0.0f);

// It is recommended to use constants instead of uniforms if the value is not changing or user-configurable.
static const float4 ConstantSingleValue = float4(0.0f, 0.0f, 0.0f, 0.0f);

Structs

Structs are user defined data types that can be used as types for variables. These behave the same as in HLSL.

struct MyStruct
{
	int MyField1, MyField2;
	float MyField3;
};

Namespaces

Namespaces are used to group functions and variables together, which is especially useful to prevent name clashing. The "::" operator is used to resolve variables or functions inside other namespaces.

namespace MyNamespace
{
	namespace MyNestedNamespace
	{
		void DoNothing()
		{
		}
	}

	void DoNothing()
	{
		MyNestedNamespace::DoNothing();
	}
}

User functions

Parameter qualifiers:

  • in Declares an input parameter. Default and implicit if none is used. Functions expect these to be filled with a value.
  • out Declares an output parameter. The value is filled in the function and can be used in the caller again.
  • inout Declares a parameter that provides input and also expects output.

Supported flow-control statements:

  • if ([condition]) { [statement...] } [else { [statement...] }]
    Statements after if are only executed if condition is true, otherwise the ones after else are executed (if it exists).
  • switch ([expression]) { [case [constant]/default]: [statement...] }
    Selects the case matching the switch expression or default if non does and it exists.
  • for ([declaration]; [condition]; [iteration]) { [statement...] }
    Runs the statements in the body as long as the condition is true. The iteration expression is executed after each run.
  • while ([condition]) { [statement...] }
    Runs the statements in the body as long as the condition is true.
  • do { [statement...] } while ([condition]);
    Similar to a normal while loop with the difference that the statements are executed at least once.
  • break;
    Breaks out of the current loop or switch statement and jumps to the statement after.
  • continue;
    Jumps directly to the next loop iteration ignoring any left code in the current one.
  • return [expression];
    Jumps out of the current function, optionally providing a value to the caller.
  • discard;
    Abort rendering of the current pixel and step out of the shader. Can be used in pixel shaders only.
// Semantics are used to tell the runtime which arguments to connect between shader stages.
// They are ignored on non-entry-point functions (those not used in any pass below).
// Semantics starting with "SV_" are system value semantics and serve a special meaning.
// The following vertex shader demonstrates how to generate a simple fullscreen triangle with the three vertices provided by ReShade (http://redd.it/2j17wk):
void ExampleVS(uint id : SV_VertexID, out float4 position : SV_Position, out float2 texcoord : TEXCOORD0)
{
	texcoord.x = (id == 2) ? 2.0 : 0.0;
	texcoord.y = (id == 1) ? 2.0 : 0.0;
	position = float4(texcoord * float2(2, -2) + float2(-1, 1), 0, 1);
}

// The following pixel shader simply returns the color of the games output again without modifying it (via the "color" output parameter):
void ExamplePS0(float4 pos : SV_Position, float2 texcoord : TEXCOORD0, out float4 color : SV_Target)
{
	color = tex2D(samplerColor, texcoord);
}

// The following pixel shader takes the output of the previous pass and adds the depth buffer content to the right screen side.
float4 ExamplePS1(float4 pos : SV_Position, float2 texcoord : TEXCOORD0) : SV_Target
{
	// Here color information is sampled with "samplerTarget" and thus from "texTarget" (see sampler declaration above),
	// which was set as render target in the previous pass (see the technique definition below) and now contains its output.
	// In this case it is the game output, but downsampled to half because the texture is only half of the screen size.
	float4 color = tex2D(samplerTarget, texcoord);
	
	// Only execute the following code block when on the right half of the screen.
	if (texcoord.x > 0.5f)
	{
		// Sample from the game depth buffer using the "samplerDepth" sampler declared above.
		float depth = tex2D(samplerDepth, texcoord).r;
		
		// Linearize the depth values to better visualize them.
		depth = 2.0 / (-99.0 * depth + 101.0);
		
		color.rgb = depth.rrr;
	}

	return color;
}

// The following compute shader uses shared memory within a thread group:
groupshared int sharedMem[64];
void ExampleCS0(uint3 tid : SV_GroupThreadID)
{
	if (tid.y == 0)
		sharedMem[tid.x] = tid.x;
	barrier();
	if (tid.y == 0 && (tid.x % 2) != 0)
		sharedMem[tid.x] += sharedMem[tid.x + 1];
}

// The following compute shader writes a color gradient to the "texTarget" texture:
void ExampleCS1(uint3 id : SV_DispatchThreadID, uint3 tid : SV_GroupThreadID)
{
	tex2Dstore(storageTarget, id.xy, float4(tid.xy / float2(20 * 64, 2 * 8), 0, 1));
}

Intrinsic functions

ReShade FX supports most of the standard HLSL intrinsics.
Check out https://docs.microsoft.com/windows/win32/direct3dhlsl/dx-graphics-hlsl-intrinsic-functions for reference on them:

abs, acos, all, any, asfloat, asin, asint, asuint, atan, atan2, ceil, clamp, cos, cosh, cross, ddx, ddy, degrees, determinant, distance, dot, exp, exp2, faceforward, floor, frac, frexp, fwidth, isinf, isnan, ldexp, length, lerp, log, log10, log2, mad, max, min, modf, mul, normalize, pow, radians, rcp, reflect, refract, round, rsqrt, saturate, sign, sin, sincos, sinh, smoothstep, sqrt, step, tan, tanh, transpose, trunc

In addition to these, ReShade FX provides a few additional ones:

float4(tex2Dfetch(s, coords * tex2Dsize(s) + int2(0, 1)).comp,
       tex2Dfetch(s, coords * tex2Dsize(s) + int2(1, 1)).comp,
       tex2Dfetch(s, coords * tex2Dsize(s) + int2(0, 1)).comp,
       tex2Dfetch(s, coords * tex2Dsize(s) + int2(0, 0)).comp)

Techniques

An effect file can have multiple techniques, each representing a full render pipeline, which is executed to apply post-processing effects. ReShade executes all enabled techniques in the order they were defined in the effect file. A technique is made up of one or more passes which contain info about which render states to set and what shaders to execute. They are run sequentially starting with the top most declared. A name is optional. Each pass can set render states. The default value is used if one is not specified in the pass body.

Annotations:

  • technique Name < enabled = true; >
    Enable (or disable if false) this technique by default.
  • technique Name < timeout = 1000; >
    Auto-toggle this technique off 1000 milliseconds after it was enabled.
    This can for example be used to have a technique run a single time only to do some initialization work, via technique Name < enabled = true; timeout = 1; >
  • technique Name < toggle = 0x20; togglectrl = false; toggleshift = false; togglealt = false; >
    Toggle this technique when the specified key is pressed.
  • technique Name < hidden = true; >
    Hide this technique in the UI.
  • technique Name < ui_label = "My Effect Name"; >
    Uses a custom name for the technique in the UI.
  • technique Name < ui_tooltip = "My Effect description"; >
    Shows the specified text when the user hovers the technique in the UI.
technique Example < ui_tooltip = "This is an example!"; >
{
	pass p0
	{
		// The primitive topology rendered in the draw call.
		// Available values:
		//   POINTLIST, LINELIST, LINESTRIP, TRIANGLELIST, TRIANGLESTRIP
		PrimitiveTopology = TRIANGLELIST; // or PrimitiveType

		// The number of vertices ReShade generates for the draw call.
		// This has different effects on the rendered primitives based on the primitive topology.
		// A triangle list needs 3 separate vertices for every triangle for example, a strip on the other hand reuses the last 2, so only 1 is needed for every additional triangle.
		VertexCount = 3;

		// The following two accept function names declared above which are used as entry points for the shader.
		// Please note that all parameters must have an associated semantic so the runtime can match them between shader stages.
		VertexShader = ExampleVS;
		PixelShader = ExamplePS0;

		// The number of thread groups to dispatch when a compute shader is used.
		DispatchSizeX = 1;
		DispatchSizeY = 1;

		// Compute shaders are specified with the number of threads per thread group in brackets.
		// The following for example will create groups of 64x1 threads:
		ComputeShader = ExampleCS0<64,1>;
	
		// RenderTarget0 to RenderTarget7 allow to set one or more render targets for rendering to textures.
		// Set them to a texture name declared above in order to write the color output (SV_Target0 to RenderTarget0, SV_Target1 to RenderTarget1, ...) to this texture in this pass.
		// If multiple render targets are used, the dimensions of them has to match each other.
		// If no render targets are set here, RenderTarget0 points to the backbuffer.
		// Be aware that you can only read **OR** write a texture at the same time, so do not sample from it while it is still bound as render target here.
		// RenderTarget and RenderTarget0 are aliases.
		RenderTarget = texTarget;

		// Clears all bound render targets to zero before rendering when set to true.
		ClearRenderTargets = false;
		
		// A mask applied to the color output before it is written to the render target.
		RenderTargetWriteMask = 0xF; // or ColorWriteEnable
		
		// Enable or disable gamma correction applied to the output.
		SRGBWriteEnable = false;

		// Enable or disable color and alpha blending.
		// Don't forget to also set "ClearRenderTargets" to "false" if you want to blend with existing data in a render target.
		BlendEnable = false;

		// The operator used for color and alpha blending.
		// Available values:
		//   ADD, SUBTRACT, REVSUBTRACT, MIN, MAX
		BlendOp = ADD;
		BlendOpAlpha = ADD;

		// The data source and optional pre-blend operation used for blending.
		// Available values:
		//   ZERO, ONE,
		//   SRCCOLOR, SRCALPHA, INVSRCCOLOR, INVSRCALPHA
		//   DESTCOLOR, DESTALPHA, INVDESTCOLOR, INVDESTALPHA
		SrcBlend = ONE;
		SrcBlendAlpha = ONE;
		DestBlend = ZERO;
		DestBlendAlpha = ZERO;
		
		// Enable or disable the stencil test.
		// The depth and stencil buffers are cleared before rendering each pass in a technique.
		StencilEnable = false;

		// The masks applied before reading from/writing to the stencil.
		// Available values:
		//   0-255
		StencilReadMask = 0xFF; // or StencilMask
		StencilWriteMask = 0xFF;
		
		// The function used for stencil testing.
		// Available values:
		//   NEVER, ALWAYS
		//   EQUAL, NEQUAL or NOTEQUAL
		//   LESS, GREATER, LEQUAL or LESSEQUAL, GEQUAL or GREATEREQUAL
		StencilFunc = ALWAYS;

		// The reference value used with the stencil function.
		StencilRef = 0;
		
		// The operation  to  perform  on  the stencil  buffer when  the
		// stencil  test passed/failed or stencil passed  but depth test
		// failed.
		// Available values:
		//   KEEP, ZERO, REPLACE, INCR, INCRSAT, DECR, DECRSAT, INVERT
		StencilPassOp = KEEP; // or StencilPass
		StencilFailOp = KEEP; // or StencilFail
		StencilDepthFailOp = KEEP; // or StencilZFail
	}
	pass p1
	{
		ComputeShader = ExampleCS1<64,8>;
		DispatchSizeX = 20; // 20 * 64 threads total in X dimension
		DispatchSizeY = 2;  //  2 *  8 threads total in Y dimension
	}
	pass p2
	{
		VertexShader = ExampleVS;
		PixelShader = ExamplePS1;
	}
}