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yart

description

code

  • Code is written in C++.
  • include/ & src/ contains all the src code.
  • examples/ contains some example scene files.
  • textures/ contains texture files.
  • assignments/ contains problem statements from which this raytracer was created.

documentation

  • The documentation for the code is itself.

usage

how to run? [linux]

  • Compile the raytracer using make to create an executable raytracer.
  • The executable reads a scene file (and possibly some texture files) and generates a ppm image.
  • Create the image of a scene using ./raytracer <path-to-scene-file>. It will be in the same directory as the scene file.
    • For example, ./raytracer examples/scene.txt creates examples/scene.ppm.

format of scene file

  • The format is similar to .obj file format.
  • Each line a the scene file defines something. Each line starts with a keyword and varying number of space separated parameters can follow.
  • All colors are in normalized scale (0 - 1).
  • The recognized keywords are as follows.
    • # ...: Comment. Will be ignored.
    • eye x y z: Camera position.
    • viewdir x y z: Camera viewing direction. Must be a unit vector.
    • updir x y z: Up direction. Must be a unit vector.
    • vfov angle: Vertical field of view in degrees.
    • imsize width height: Output image dimensions in pixels.
    • bkgcolor r g b: Background color.
    • light x y z w r g b: A light source.
      • x y z is position.
      • w can be 0 (directional source) or 1 (point source).
      • r g b is color.
    • mtlcolor Odr Odg Odb Osr Osg Osb ka kd ks n a h: Material color.
      • Odr Odg Odb is diffusion color.
      • Osr Osg Osb is specular color.
      • ka kd ks are ambient, diffusion and specular co-efficients respectively in the Blinn-Phong model.
      • n is the power in Blinn-Phong model.
      • a is opacity level (0 - 1).
      • h is refractive index.
    • texture <path-to-texture-file>: Path is assumed to start from raytracer executable directory. Has to be a valid ppm file.
    • sphere x y z radius: A spherical object.
    • v x y z: Vertex position.
    • vt u v: A texture coordinate. u & v must be in [0, 1].
    • vn x y z: A vertex normal definition. Must be a unit vector.
    • f ...: A face of a triangle.
      • All following arguments are indices of previously defined entities. The entities are counted from starting from 1 (and not 0).
      • f v1 v2 v3: v1 v2 v3: Vertex indices.
      • f v1/vt1 v2/vt2 v3/vt2: Vertex indices annotated with texture coordinate indices.
      • f v1//vn1 v2//vn2 v3//vn3: Vertex indices annotated with vertex normal indices.
      • f v1/vt1/vn1 v2/vt2/vn2 v3/vt3/vn3: Vertex indices annotated with texture coordinate indices & vertex normal indices.
    • parallel: Presence indicates that parallel projection is to be used. Default is perspective.
    • viewdist distance: Viewing distance for depth of field effect.
  • Once a material color or texture is defined, it will be used for all the following objects in the scene until another is defined.
  • For integer parameters, don't add a succeding decimal part.
    • 1 is ok.
    • 1. is not okay. 1.0 is not okay.
    • This is caused merely because of the cin construct behaviour and has nothing to do with the ray tracer.

ray tracer configuration

  • Ray tracer has some configurable parameters, as listed with the defaults below.
name description default
CAMERA_MEDIUM_REFRACTIVE_INDEX Refractive index of medium camera is placed in. 1
CAMERA_MEDIUM_OPACITY Opacity of medium camera is placed in. 0
RECURSIVE_DEPTH Number of times a ray reflects/refracts. Higher value produces more realistic effects. 6
SOFT_SHADOW_JITTER Measure of dispersion of shadow rays. Higher value produces softer shadows. 0
NUM_SHADOW_RAYS_PER_POI Number of shadow rays. Higher value produces softer shadows. 1
NUM_DISTRIBUTED_RAYS Number of rays traced per pixel. Higher value produces more diffused image. 10
DISTRIBUTED_RAYS_JITTER Measure of dispersion of rays traced per pixel. Higher value produces more diffused image. 5e-2
  • To change config, directly edit these values in src/main.cpp and recompile.

roadmap

raytracer

  • Ray sphere intersection.
  • Ray triangle intersection (barycentric coordinates).
  • Blinn-Phong reflection model.
  • Point and directional source of light.
  • Shadows.
  • Smooth shadows.
  • Subtractive shadows.
  • Spheres.
  • Triangules.
  • Vertex normals, and their interpolation.
  • Textures for spheres and triangles, Texture coordinates and their interpolation.
  • Recursive ray tracing (using schlick’s approximation of the Fresnel reflectance).
  • Refraction.
  • Total internal reflection.
  • Depth of field effect using distributed ray tracing.
  • Parallel projection (not done properly, pulls the camera extremely far back).
  • Spotlights.
  • Attenuation.

I/O

  • Parser. Recognized keywords, Input validation, Good error messages.
  • PPM writer.
  • PPM reader for textures.

misc

  • To string for all types.
  • Vec3d structure.

bug fixes

  • Invalid number of args fix.
  • Output file name fix.
  • Accept empty lines.
  • Ignore unknown keywords.
  • Sometimes your rays go through triangles without detecting the intersection.
  • Your texture parser doesnt always work, there might be newlines or whitespace at the end of a line.
  • Your shadows aren't correct sometimes.
  • texture paths.
  • 1c testcases.
  • 1d testcases.