lite5h4dow / raytracer

A faily traditional raytracer

Raytracer

A faily traditional raytracer.

Functionality implemented so far.

Primitives

• Spheres
• Triangles
• Planes
• Meshes loaded from wavefront obj files. Supports mtl files
• Multiple instances of those Meshes, independently transformed
• Tori (Toruses, Donuts....Mmm Donuts!)
• Cylinders
• Cubes
• Cones

Effects

• Reflections
• Refractions

Various Materials

• Plain RGB materials defined with Ambient, Diffuse etc etc etc.
• Checker Board of two submaterials.
• Perlin Noise mix of two submaterials.
• Texture material. UV coordinate calculations are specific to each primitive type. All common image file formats are supported via the .net framework.
• Cubemaps, both vertical and horizontal crosses, are supported for scene backgrounds. When a ray misses all objects in the scene we render from the cubemap.

Lights

• Point Light - Simple light at a point in space casting light in all directions. Obeys the inverse square law and can cause shadows.
• Ambient Light - Has no position and contributes the same light to every point in space. Casts no shadows.
• Spot Light - Like a point light but has a direction and width in addtion to position. It casts a cone of light along its direction. The width determines the angle of the cone. Casts shadows.
• Distant Light - Has no position but does have a direction. Useful for simulating the sun for example. Casts shadows.
• Projection Light - Like a spot light but projects a texture into the scene. Think overhead projector and you'll not be far off.
• Area Lights. Currently just Spherical but I will expand to disc and quads. Custom sampling threshlold per light. Casts soft shadows.

Lights and most primitives take a Transform object instead of explicit positions, rotations etc. The new file format then has several methods of producing a Transform. Explicit translations and rotations, lookat matricies, axis angles etc and they could all be used where ever appropriate.

File Types

• XML Based renderer and scene definition files.
• Wavefront obj files.
• Wavefront mtl files.

Antialiasing

• Multiple antialiasing algorithms possible. Currently implemented are :
• Non anti aliased,
• Progressive rendering. 64px square regions followed by 32px etc.
• NxN jittered samples per pixel
• Greyscale Edge Detection Jittered Resampling.
• Per Component (RGB) Edge Detection Jittered Resampling.

Accelleration Structures

• Octree
• Bounding Volume Hierarchy, AABBs in my case.
• Multi Axis Midpoint Split Criteria
• Multi Axis SAH Split Criteria

Sampling Stratigies

• Random
• Stratified

Still to come

Bump mapping, more area lights and a path tracer implementation and a BRDF system.

Examples

• Refraction needs some work in this one
• Reflective sphere and cubemap
• Refractive sphere and cubemap
• Colourful room
• Mesh instances
• Texture mapped triangles
• Texture mapped sphere
• Perlin noise mixing base materials, red, yellow and texture.
• Mesh self shadowing.
• Torus.
• Refractive Torus.
• Transformed Tori.
• Mesh instancing and transformations.
• Mesh instancing and transformations.
• 280 interlinked tori with various levels of reflectivity and refraction.
• Cylinders. They support all the usual materials.
• Texture Coordinate Wrapping.
• 1,087,474 triangle Happy Buddha.
• Spot lights.
• Projector light.
• Cryteks version of the Sponza Model. Still work to do
• Four Spherical Area Lights. 256 shadow rays per light.
• Soft Shadow from area light.
• New cube primitive Supports arbitrary scaling.
• Scaled Torus
• Cone primitive displaying reflection.
• Cylinders with soft shadows.
• Meshes from xml file format.
• Same mesh rendered with 512 shadow rays for a spherical area light. Total render time was 4hr 47min.
• Stanford Dragon model, 128 shadow rays. 1 hr 47 mins rendering time.
• Refractive Stanford Dragon model. Glass material. Two sphericsal area lights and 128 shadow rays each. 23 hr 58 mins rendering time!

That's all for now.