The Globals object

The Globals Object encapsulates many options you can feed to the renderer before it starts tracing photons

Here follows an explanation of all the settings divided by category

Samping

epsilon: This value is used to determine the minimum precision value used for various calculations, lowering/increasing it too much can cause precision issues and incorrect renders

highPrecision: setting highPrecision to true will switch to Float64Arrays for every calculation made inside the renderer, those are obviously more expensive to work with and you can expect a 2x slowdown from using them. If changes to the epsilon value are not solving the precision issues you encounter, setting highPrecision to true might be your only option

USE_STRATIFIED_SAMPLING: wether the renderer should use stratified sampling or not

samplingRatioPerPixelCovered: variable determining how many samples are taken from a line, eg. if a light ray is "200 pixels long" the amount of pixels drawn would be floor(light_ray_pixel_length * samplingRatioPerPixelCovered); the expected range is [0...1] values towards 1 will draw more samples per line, so expect more pixels drawn but a lower number of photons fired values towards 0 will draw less samples per line, so expect less pixels drawn but a bigger number of photons fired

LIGHT_BOUNCES: how many light bounces to compute for each photon

skipBounce: how many light bounces to skip from each photon fired. If the photon bounces 4 times around the scene and skipBounce is set to 1, the first "bounce" of light wont be drawn in the canvas, but the bounce is still computed

Threading

workersCount: the amount of web workers to spawn, each will start a new thread to speed up rendering. Its advised to not use more workers than the number of cores in your processor. Every browser has its limits on how many web workers can be spawned, Chrome currently can handle at most 60 (but believe me you'll fry your browser with much less than that)

PHOTONS_PER_UPDATE: only used to print to the console the amount of photons fired and colored pixels at an interval specified by the value

Environment

WORLD_SIZE vertical extent of the world with respect to the canvas size, if WORLD_SIZE is set to 20, the top corner of the canvas will have a world y coordinate of 10, and the bottom coordinate of the canvas element will have a world y coordinate of -10

worldAttenuation the amount of radiance lost as a photon travels through the scene

Video Export

registerVideo: wether you want to register the frames rendered as a .webm video

photonsPerVideoFrame: amount of photons to trace for each frame before computing the next one

framesPerSecond: fps of the final video

framesCount: amount of frames to render

frameStart: starting frame of the video

Motion Blur

motionBlur: enables motion blur if set to true. This will effectively make the renderer call multiple times the createScene function, each time with a random number in the range [0...1] for the motionBlurT parameter, this makes it possible to create blurred animations and video frames

motionBlurFramePhotons: amount of photons traced before createScene is called again with a different motionBlurT parameter. If your createScene function takes a lot of time to compute you should evaluate carefully how many photons to trace before calling the function again

Offscreen canvas

deactivateOffscreenCanvas: if set to false, an offscreen canvas can is activated to draw on it as you would do with the standard javascript canvas API. Activating an oc canvas slows down render times by about 1.7x. The canvas image will then be used to increase / decrease the radiance contribution along the pixels covered by the canvas, see scenes/offscreenCanvas.js for an example on how to use the offscreen canvas

offscreenCanvasCPow: how strongly the radiance is modified along pixels drawn by the offscreen canvas

Canvas size

canvasSize {
   width: 800,  // width of the main canvas in pixels
   height: 800, // height of the main canvas in pixels
}

Reinhard tonemapping

toneMapping: enables / disables Reinhard tonemapping

gamma: gamma correction value

exposure: exposure value