This page details how to set up a custom shader for visualisation. This can be used in the to unpack or decode complex formats, or simply apply a custom complex transformation to the image beyond the default controls.

# Introduction

The basic process of setting up the custom shader involves writing a .hlsl or .glsl file that will be compiled and used by RenderDoc. Note that the type used matches the API used, and RenderDoc will automatically list only the hlsl shaders you have if you load a log with D3D11, and vice-versa for OpenGL.

There are several special global variables that can be specified and will be filled in with values by RenderDoc.

Your pixel shader defines an operation that transforms the raw value from the input texture into a value that will then be displayed by the texture viewer. The usual texture viewer controls for range adaption and channels will still be available on the resulting texture.

Multisampled textures will be resolved before being passed to your function. Depth and stencil textures will be bound separately and passed as multisampled resources.

To set up your shader, it's recommended that you use the UI defined in the documentation for the , but you can manually create a .hlsl or .glsl file in %APPDATA%\RenderDoc\. The file must contain an entry point main() that returns float4, and uses any of the below inputs. These shaders are loaded when RenderDoc loads a logfile, and RenderDoc watches for any changes to the files (either externally or in the shader editor in RenderDoc) and automatically reloads them.

# Predefined inputs

There are several pre-defined inputs that can either be taken as parameters to the shader entry point, or defined as global variables with a particular name that will then be filled in. There are also definitions for the different type of input textures.

Type and capitalisation is important for these variables, so ensure you use the right declaration!

The shader editor when using the UI can be used to insert these snippets for you, with the right type and spelling. Be careful for GL though, as these snippets are inserted at the top of the file and so are inserted before the #version statement.

Input | Explanation

UV co-ordinates (D3D11 only)

`float4 main(float4 pos : SV_Position, float4 uv : TEXCOORD0) : SV_Target0 { return 1; }`

This input is defined as two parameters to the shader entry point. The first defines the usual SV_Position system semantic, and the first two components of the second TEXCOORD0 parameter gives UV co-ordinates from 0 to 1 in each dimension over the size of the texture (or texture slice).

You must bind these parameters like this in this order to ensure the linkage with the vertex shader matches.

Texture dimensions

`uint4 RENDERDOC_TexDim; // hlsl uvec4 RENDERDOC_TexDim; // glsl`

This variable will be filled out with the following values:

- .x = Width

- .y = Height (if 2D or 3D)

- .z = Depth if 3D or array size if an array

- .w = Number of mip levels

Selected Mip level | `uint RENDERDOC_SelectedMip;` This variable will be filled out with the selected mip level in the UI.

Current texture type

`uint RENDERDOC_TextureType;`

This variable will be set to a given integer value, depending on the type of the current texture being displayed. This can be used to sample from the correct resource.

The value varies depending on whether this is an HLSL shader or GLSL, as they have different resource types.

D3D11 / HLSL

- 1D texture

- 2D texture

- 3D texture

- Depth

- Depth + Stencil

- Depth (Multisampled)

- Depth + Stencil (Multisampled)

- Cubemap

- 2D texture (Multisampled)

OpenGL / GLSL

- 1D texture

- 2D texture

- 3D texture

- Cubemap

- 1D array texture

- 2D array texture

- Cubemap array

- Rectangle

- Buffer texture

- 2D texture (Multisampled)

Samplers (D3D11 only) | `SamplerState pointSampler : register(s0); SamplerState linearSampler : register(s1);` These samplers are provided to allow you to sample from the resource as opposed to doing straight loads. They are bound by slot and not by variable name - so this means you can name them as you wish but you must specify the register binding explicitly.

Resources

D3D11 / HLSL

`Texture1DArray<float4> texDisplayTex1DArray : register(t1); Texture2DArray<float4> texDisplayTex2DArray : register(t2); Texture3D<float4> texDisplayTex3D : register(t3); Texture2DArray<float2> texDisplayTexDepthArray : register(t4); Texture2DArray<uint2> texDisplayTexStencilArray : register(t5); Texture2DMSArray<float2> texDisplayTexDepthMSArray : register(t6); Texture2DMSArray<uint2> texDisplayTexStencilMSArray : register(t7); Texture2DArray<float4> texDisplayTexCubeArray : register(t8); Texture2DMSArray<float4> texDisplayTex2DMSArray : register(t9); Texture1DArray<uint4> texDisplayUIntTex1DArray : register(t11); Texture2DArray<uint4> texDisplayUIntTex2DArray : register(t12); Texture3D<uint4> texDisplayUIntTex3D : register(t13); Texture2DMSArray<uint4> texDisplayUIntTex2DMSArray : register(t19); Texture1DArray<int4> texDisplayIntTex1DArray : register(t21); Texture2DArray<int4> texDisplayIntTex2DArray : register(t22); Texture3D<int4> texDisplayIntTex3D : register(t23); Texture2DMSArray<int4> texDisplayIntTex2DMSArray : register(t29);`

OpenGL / GLSL

`// Unsigned int samplers layout (binding = 1) uniform usampler1D texUInt1D; layout (binding = 2) uniform usampler2D texUInt2D; layout (binding = 3) uniform usampler3D texUInt3D; // skip cube = 4 layout (binding = 5) uniform usampler1DArray texUInt1DArray; layout (binding = 6) uniform usampler2DArray texUInt2DArray; // skip cube array = 7 layout (binding = 8) uniform usampler2DRect texUInt2DRect; layout (binding = 9) uniform usamplerBuffer texUIntBuffer; layout (binding = 10) uniform usampler2DMS texUInt2DMS; // Int samplers layout (binding = 1) uniform isampler1D texSInt1D; layout (binding = 2) uniform isampler2D texSInt2D; layout (binding = 3) uniform isampler3D texSInt3D; // skip cube = 4 layout (binding = 5) uniform isampler1DArray texSInt1DArray; layout (binding = 6) uniform isampler2DArray texSInt2DArray; // skip cube array = 7 layout (binding = 8) uniform isampler2DRect texSInt2DRect; layout (binding = 9) uniform isamplerBuffer texSIntBuffer; layout (binding = 10) uniform isampler2DMS texSInt2DMS; // Floating point samplers layout (binding = 1) uniform sampler1D tex1D; layout (binding = 2) uniform sampler2D tex2D; layout (binding = 3) uniform sampler3D tex3D; layout (binding = 4) uniform samplerCube texCube; layout (binding = 5) uniform sampler1DArray tex1DArray; layout (binding = 6) uniform sampler2DArray tex2DArray; layout (binding = 7) uniform samplerCubeArray texCubeArray; layout (binding = 8) uniform sampler2DRect tex2DRect; layout (binding = 9) uniform samplerBuffer texBuffer; layout (binding = 10) uniform sampler2DMS tex2DMS;`

These resources are bound sparsely with the appropriate type for the current texture. With a couple of exceptions there will only be one texture bound at any one time.

When a cubemap texture is bound, it is bound both to the 2D Array as well as the Cube Array. If a depth-stencil texture has both components, the relevant depth and stencil resources will both be bound at once.

To determine which resource to sample from you can use the RENDERDOC_TexType variable above.

Usually the float textures are used, but for unsigned and signed integer formats, the relevant integer resources are used.

As with the samplers, these textures are bound by slot and not by name, so while you are free to name the variables as you wish, you must bind them explicitly to the slots listed here.