Sample Usages of Cyfra - Brushed Material Simulation and Raytraced Solar System

[BlagoGunev]

Brushed Material Simulation:

Implements some features of a raytracer such that a scene containing a sphere and a light source can be drawn.
The ray bounces off of the sphere and gets a color sample from an environment map created using the existing implementation of gradient generation. Multiple samples are taken to simulate a look of brushed material.

Implementation:

The sample is retrieved from the gradient with an offset depending on the ray direction. I used sine to make the effect more appealing:

def sampleEnvironment(rayDir: Vec3[Float32])(using animationInstant: AnimationInstant): Vec3[Float32] =
      val f = smooth(from = 0f, to = 5f, duration = 5.seconds) + sin(3f  * rayDir.x) + rayDir.y * 2f
      val brightness = vec3(0.3f, 0.4f, 1f)
      val contrast = vec3(0.25f, 0.5f, 0f)
      val freq = vec3(1f)
      val offsets = vec3(0.5f, 0f, 0f)
      igPallette(brightness, contrast, freq, offsets, f)

In here a basis orthogonal to the reflected ray direction is created so that an offset for the reflection can be taken. Then, the offset is sampled uniformly from a disk. This simulates the imperfections in reflections in real life by making the reflection direction be more random. Multiple samples are taken to make the result closer to how a real world object would look like.

GSeq.gen(
          first = RayState(nextRayPos, reflectDir, sampleEnvironment(reflectDir) * (1f / REFLECTION_SAMPLES), random),
          next = {
            case state@RayState(rayPos, rayDir, color, random) =>
              val (rand1, angle) = random.next[Float32]
              val (rand2, scale) = rand1.next[Float32]
              val sqrScale = sqrt(scale) / 2f
              val firstBasis = getOrthogonal(rayDir, hitInfo.normal)
              val secondBasis = getOrthogonal(firstBasis, rayDir)
              val wiggle = (firstBasis * sin(angle) + secondBasis * cos(angle)) * sqrScale
              val newSample = sampleEnvironment(normalize(rayDir + wiggle))
              RayState(
                rayPos = rayPos,
                rayDir = rayDir,
                color = color + newSample * (1f / REFLECTION_SAMPLES),
                random = rand2
              )
          }
        ).limit(REFLECTION_SAMPLES).lastOr(
          RayState(vec3(0f), vec3(0f), vec3(0f), random)
        )

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Raytraced Solar System:

The visualization showcases something similar to Earth's orbit around the Sun and how the Moon can cause solar eclipses. It is all done using the existing raytracing implementation.