Sample - Ray Marching and Signed Distance Functions

[notrichardpeng]

This is a sample that renders a 3D torus and box using ray marching and signed distance functions. Ray marching iteratively projects a ray in space and uses signed distance functions of various shapes to decide whether it has hit them:

def rayMarch(origin: Vec3[Float32], rayDirection: Vec3[Float32])(using AnimationInstant): Float32 =
  GSeq.gen[Float32](getDistance(origin), next = dist => {
    val currPosition = origin + (rayDirection * dist)
        val currDistance = getDistance(currPosition)
        dist + currDistance
    })
    .takeWhile(dist => dist > MIN_DIST && dist < MAX_DIST)
    .limit(MAX_STEPS)
    .lastOr(MAX_DIST)

The getDistance() function effectively renders the scene. It returns the distance to the nearest object in the scene. Since we have a torus and a box, we calculate the distance to both and return the minimum (we see whichever is nearest). We use a smooth min function to create a blending effect of the objects when they are close in distance. A similar smoothing technique is applied to blend the color of the two objects.

val torus = sdfTorus(p, TORUS_RADII, position)
val box = sdfBox(BOX_POSITION, BOX_SIZE, position)        
smoothMin(torus, box, 0.5f)

The lighting is calculated using getLight(), which uses the dot product of a vector from the light source to the surface of the object. The scene is animated using Cyfra's animation tools.

The following is the result:

output.mp4