riow-208-volumes

RIOW 2.08: Volumes

View shader on Shadertoy - Published on 2018-09-07

These shaders are my implementation of the raytracer described in the (excellent) book "Ray tracing in one weekend" and "Ray tracing: the next week"[1] by Peter Shirley (@Peter_shirley). I have tried to follow the code from his book as much as possible, but I had to make some changes to get it running in a fragment shader:

• There are no classes (and methods) in glsl so I use structs and functions instead. Inheritance is implemented by adding a type variable to the struct and adding ugly if/else statements to the (not so overloaded) functions.
• The scene description is procedurally implemented in the world_hit function to save memory.
• The color function is implemented using a loop because it is not possible to have a recursive function call in glsl.
• Only one sample per pixel per frame is calculated. Samples of all frames are added in Buffer A and averaged in the Image tab.

Besides that, I also made some other design choices. Most notably:

• In my code ray.direction is always a unit vector so I could clean up the rest of the code by removing some implicit normalizations.
• Cosine weighted hemisphere sampling is used for the Lambertian material.

You can find the raytracer / pathtracer in Buffer A.

= Ray tracing in one week =

• Chapter 7: Diffuse https://www.shadertoy.com/view/llVcDz
• Chapter 9: Dielectrics https://www.shadertoy.com/view/MlVcDz
• Chapter 11: Defocus blur https://www.shadertoy.com/view/XlGcWh
• Chapter 12: Where next? https://www.shadertoy.com/view/XlycWh

= Ray tracing: the next week =

• Chapter 6: Rectangles and lights https://www.shadertoy.com/view/4tGcWD
• Chapter 7: Instances https://www.shadertoy.com/view/XlGcWD
• Chapter 8: Volumes https://www.shadertoy.com/view/XtyyDD
• Chapter 9: A Scene Testing All New Features https://www.shadertoy.com/view/MtycDD

[1] http://in1weekend.blogspot.com/2016/01/ray-tracing-in-one-weekend.html

Shaders

Buffer A

Source: Buffer A.glsl

Inputs

• iChannel0: Buffer A (linear, clamp, vflipped)

Image

Source: Image.glsl

Inputs

• iChannel0: Buffer A (linear, clamp, vflipped)

Links

• RIOW 2.08: Volumes on Shadertoy
• An overview of all my shaders
• My public profile on Shadertoy
• http://in1weekend.blogspot.com/2016/01/ray-tracing-in-one-weekend.html

License

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.