YAML omg Raytracer

This document describes the YAML description of the omg raytracer.

A quick-start example

raytracer:
    camera:
        width: 800
        height: 600
        position: [0.0, 0.0, 0.0]       
        target: [0.0, 0.0, -10.0]       
        up: [0.0, 1.0, 1.0]    
        fdist: 1.0             
        v_angle: 45.0
    background:
        type: solid
        color: [255, 0, 0]
    scene:
        materials:
            - type: flat
              label: redish
              color: [255, 0, 0]
        objects:
            - type: sphere
              center: [0, 0, 2]
              radius: 0.4
              material: redish
    settings:
        integrators:
            - type: flat
            - type: normal_map

Syntax

raytracer

This is the main section of the description. It has all top level elements to produce a 3D image, like camera and background. The quick-start example is a good view of this construction.

Attributes

• camera
• background
• scene
• settings

camera

This represents a camera.

Attributes

• type: [orthographic | perspective]
• width: the image width
• height: the image height
• position: camera location
• target: direction to which the camera is looking
• up: vector normal to the top of the camera
• view_normal: the normal vector with respect to the view plane (for oblique views)

Type-specific attributes

• orthographic
  • vpdims: l r b t
• perspective
  • defining the field of view
    • fdist: focal distance
    • v_angle: vertical angle of view
    • aspect_ratio: the aspect ratio, otherwise computed as width/height
  • defining the view port
    • fdist: focal distance
    • vpdims: l r b t

background

The scene background.

Attributes

• type: [solid | gradient]

Type-specific attributes

• solid
  • color
• gradient
  • colors: up to 4 colors (more than that will be ignored), given clock-wise from the top left corner. Less than 4 colors will make the last one to be repeated in the remaining corners.

scene

The scene elements.

lights

• intensity: light color, 3D vector in [0,255]
• type: [point, spot, directional]

Type-specific attributes

• point
  • position: light position, 3D vector
• spot
  • position: light position, 3D vector
  • point_at: to where the source is pointing, 3D vector
  • cutoff: main focus angle, float
  • falloff: total angle, float
• directional
  • direction: light direction

materials

• type: [flat, blinn]

Type-specific attributes

• flat
  • color: the material color
• blinn
  • ambient: influence of the ambient light, 3D vector in [0,1]
  • diffuse: influence of diffuse light, 3D vector in [0,1]
  • specular: influence of specular light, 3D vector in [0,1]
  • glossiness: plastic aspect, 3D vector in [0,1]
  • mirror: how much this material reflects light (mirror-like effect), 3D vector in [0,1]

objects

• type: [sphere, triangle_mesh, aggregate]
• material: a label of some declared material
• transform: a list of transforms to be applied in the object (check misc elements for details)

Type-specific attributes

• sphere
  • radius: radius (float)
  • center: a vector
• triangle_mesh
  • obj_file: o .obj file having a mesh description
  • clockwise: if triangles specified in clockwise orientation
  • compute_normals: force the computation of normals (applicable for obj_file specification)
  • ntriangles: number of triangles
  • indices: 2*ntriangles indices for the vertices of each triangle
  • vertices: list of vertices
  • normals: list of vertex normals
• aggregate
  • structure: a description of the acceleration structure (see below)
  • objects: a list of objects
  • label: a label

settings

Running settings of the raytracer.

integrators

The integrators to be run over the description. At least the following attributes must be specified:

• type: [flat | normal_map | depth | blinn]

Type-specific attributes

• depth:
  • near_color: the color of the nearest objects
  • far_color: the color of the fartest objects

Misc elements

structure

• type: [bvh, list]

type-specific attributes

• bvh
  • max_prim_nodes: the maximum number of primitives in a leaf
  • split_method: [middle, equal_counts]
• list

transform

• type: [scale, rotation_x, rotation_y, rotation_z, rotation, translation]

type-specific attributes

• scale
  • xyz: scale factors in each axis
• rotation_x
  • angle
• rotation_y
  • angle
• rotation_z
  • angle
• rotation
  • axis: rotation axis
  • angle
• translation
  • delta: translation delta in each axis