RayTK

RayTK is a library of TouchDesigner components that construct raymarching shaders (and other types of shaders) with networks of COMPs using the TouchDesigner network editor.

RayTK consists of a set of operator (ROP) components, and a set of tools for working with them.

Getting Started

Check out the Getting Started guide on the documentation website.

Troubleshooting

Check out the Troubleshooting Guide.

How RayTK works

Output ROPs

An SDF on its own is just a chunk of data. It needs to be sent to a special "Output" ROP, such as raymarchRender3d. These special ROPs take in one or more ROP inputs, construct a shader based on those inputs, and runs it in a GLSL TOP, to produce various types of image outputs. As the name suggests, raymarchRender3d uses the ROP network to build a raymarching shader, producing a rendered view of your scene, from some sort of camera. It's analagous to a Render TOP, which takes in some Geometry COMPs and renders them to an image.

Regular ROPs and Definition Tables

Each regular (non-output) ROP produces a single output, a DAT containing a data table describing that ROP and all of its inputs. They are known as "Definitions". Unless you are developing the core of the RayTK library itself, you will never need to deal directly with the contents of the definitions. They should be treated as an opaque data type. They're just the "thing" that comes out of a ROP.

Data Types

There are several types of data that a ROP function can return, including:

• Sdf: An SDF result, including surface distance, material settings, and other properties.
• float: A single floating point value. These can be used to drive the parameters of other ROPs, such as applying different amounts of rotation for different points in space.
• vec4: A 4-part vector value. These can be used to drive the parameters of other ROPs, such as applying colors based on position in space.
• Ray: A position and direction. These are returned by camera ROPs, to determine what direction the ray should march for each pixel of the output.
• Light: A point in space, and an amount of color. These are returned by light ROPs.

There are several types of coordinates that a ROP can use:

• vec3: 3D coordinates, which are the main coordinate type for SDFs and raymarching.
• vec2: 2D coordinates, which are used in 2D SDFs, texture lookups, and screen UV coordinates.
• float: 1D coordinates, which can be used for 1D vector fields.

Execution Chain

The Output ROP at the end of a chain of ROPs generates a shader along with things like uniforms, textures, etc. It then runs that shader in a GLSL TOP and outputs the results.

Each type of Output ROP has a block of GLSL called the "body", which contains the main() function. The body code will call functions from input ROPs for various purposes.

In the case of render2d (when using a vector field input ROP), it calls the input function once per pixel, to determine the color of that pixel.

In the case of raymarchRender3d, the main scene input is executed once per each step of the rays. In addition to the scene input, raymarchRender3d has an input for a camera function, which called for each pixel of output to determine where the ray goes, and a light function that is called by materials to determine colors.

How and Why Was This Created

The goal of RayTK is to allow artists without a strong knowledge of GLSL to render raymarched scenes, using the familiar elements of the TouchDesigner network editor. Raymarching has been around for a long time, but it is very different from traditional rendering, and it requires a strong knowledge of GLSL and vector math.

RayTK is a ground-up rewrite of a previous similar project, which was based on Patrik Lechner's TDRaymarchToolkit, which was based on hg_sdf and the work of Inigo Quilez.

License

RayTK by tekt (Tommy Etkin) is licensed under CC BY 4.0