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1/ ShadyTracer: physically based light in the browser 🧵 A WebGPU path tracer that renders in real units, cd/m² and lux, with a scene builder, a measuring tool and an optics bench for LED and luminaire design. Free and open source (MIT): shadytracer.com github.com/lampmaker/Sh... #pathtracing

2/ Nothing to install, no server. The page runs on your own graphics card, and your projects are kept in the browser as you work. Every surface is a signed distance function: exact code, not a mesh, so a sphere is a sphere at any zoom.

3/ Light in physical units. The sun is set by the lux it delivers, at its real 0.53° size; the sky by the lux it puts on the ground. A white floor under both reads its textbook value to 0.1 %. One layered material model for everything, energy conserved to 0.04 % in a white furnace test.

4/ Glass the way glass behaves: caustics from photons traced from the sun, a photon map for what's seen through glass or in a mirror, dispersion that splits white light in a prism, dichroic coatings. Any glowing surface is a light. And a haze box, so beams show in dusty air. #raytracing

5/ Light as numbers: switch the view to lux on surfaces, or luminance in cd/m², in false colour. Every pixel carries an error bar. Pin a point or draw an area: mean ± error, min, max, uniformity U0, CCT and Duv.

7/ The optics bench traces the same scene the picture shows, so the numbers and the picture can't disagree. LEDs, lenses, detectors, Zemax ray files. Far field in candela with beam and field angles, illuminance maps in lux, colour uniformity. Every number with its standard error. #opticsdesign

8/ Also: STEP and STL parts imported as exact, editable shapes; STL and 3MF export with colour for multi-colour 3D printing; keyframe any setting and render it to MP4 or GIF.