01 SDF/
SIGNED DISTANCE FIELDS
A raymarched torus shaded with a wireframe-ish distance grid.
sdf/readme.md
Approach
A single torus, described by a two-line distance function, sphere-traced in a fragment shader. The interesting part is the shading: instead of a texture, the surface is parameterised by its own angles and a grid is drawn analytically in that space, so lines stay one pixel wide at any distance.
Techniques
- Sphere tracing with relaxed over-stepping and a final bisection.
- Normals from a tetrahedral central-difference stencil (four taps, not six).
- Screen-space derivative (
fwidth) based line antialiasing for the grid.
What to look at
The grid lines thin and thicken with curvature — that is the derivative-based antialiasing doing its job, not a texture mip.