Fun with ray tracing Shell based local ambient occlusion approximation Instead of a single shell hemisphere use multiple hemispheres to provide a better approximation as the hemispheres grow in radius their contribution is scaled function validf val if typeof val undefined throw Error invalid value if isNaN val throw Error NaN value if val 9999999 throw Error number warning range if val 9999999 throw Error number warning range function validv val if typeof val undefined throw Error invalid value validf val x validf val y validf val z function vec3 x y z if typeof x undefined x 0 if typeof y undefined y 0 if typeof z undefined z 0 if typeof x number throw Error invalid value not a number if typeof y number throw Error invalid value not a number if typeof z number throw Error invalid value not a number this x x this y y this z z validv this return this vec3 add function v0 v1 return new vec3 v0 x v1 x v0 y v1 y v0 z v1 z vec3 add3 function v0 v1 v2 validv v0 validv v1 validv v2 return vec3 add v0 vec3 add v1 v2 vec3 sub function v0 v1 return new vec3 v0 x v1 x v0 y v1 y v0 z v1 z vec3 scale function v0 s return new vec3 v0 x s v0 y s v0 z s vec3 mult function v0 v1 return new vec3 v0 x v1 x v0 y v1 y v0 z v1 z vec3 cross function v0 v1 return v0 x v1 y v0 y v1 x vec3 cross function v0 v1 return new vec3 v0 y v1 z v0 z v1 y v0 z v1 x v0 x v1 z v0 x v1 y v0 y v1 x vec3 dot function v0 v1 return v0 x v1 x v0 y v1 y v0 z v1 z note you can t use length word vec3 dist function v0 return Math sqrt v0 x v0 x v0 y v0 y v0 z v0 z vec3 norm function v0 let ln Math sqrt v0 x v0 x v0 y v0 y v0 z v0 z validf ln return vec3 scale v0 1 0 ln function Ray o_ d_ this o o_ this d d_ validv this o validv this d const REFL DIFF 0 SPEC 1 REFR 2 material types function Sphere r_ p_ e_ c_ refl_ this r r_ radius this p p_ position this e e_ emission this c c_ color this refl refl_ reflection type DIFFuse SPECular REFRactive this intersect function ray returns distance 0 if nohit let op vec3 sub this p ray o Solve t 2 d d 2 t o p d o p o p R 2 0 let eps 1e 4 let b vec3 dot op ray d let det b b vec3 dot op op this r this r if det 0 return 0 else det Math sqrt det let t b det return t eps t t b det eps t 0 const spheres Scene radius position emission color material new Sphere 1e5 new vec3 1e5 1 40 8 81 6 new vec3 new vec3 1 0 25 25 REFL DIFF Left new Sphere 1e5 new vec3 1e5 99 40 8 81 6 new vec3 new vec3 25 1 0 75 REFL DIFF Rght new Sphere 1e5 new vec3 50 40 8 1e5 new vec3 new vec3 25 25 1 0 REFL DIFF Back new Sphere 1e5 new vec3 50 40 8 1e5 170 new vec3 new vec3 REFL DIFF Frnt new Sphere 1e5 new vec3 50 1e5 81 6 new vec3 new vec3 1 0 1 0 25 REFL DIFF Botm new Sphere 1e5 new vec3 50 1e5 81 6 81 6 new vec3 new vec3 0 25 1 0 1 0 REFL DIFF Top new Sphere 16 5 new vec3 27 16 5 47 new vec3 new vec3 0 99 0 0 99 REFL SPEC Mirr new Sphere 16 5 new vec3 73 16 5 78 new vec3 new vec3 0 99 0 99 0 99 REFL REFR Glas new Sphere 600 new vec3 50 681 6 27 81 6 new vec3 12 12 12 new vec3 REFL DIFF Lite function clamp x return x 0 0 x 1 1 x function toInt x return Math round Math pow clamp x 1 2 2 255 5 function intersect o o ray t id const n spheres length let inf 1e20 o t inf for let i n i let d spheres i intersect o ray if d d o t o t d o id i return o t inf function erand48 return Math random const M_PI Math PI const cos Math cos const sin Math sin const sqrt Math sqrt const fabs Math abs function trace ray depth Xi const Ray r int depth unsigned short Xi let t distance to intersection let id 0 id of intersected object let o ray ray t t id id if intersect o return new vec3 if miss return black id o id t o t const obj spheres id the hit object const x vec3 add ray o vec3 scale ray d t validv x const n vec3 norm vec3 sub x obj p validv n let nl vec3 dot n ray d 0 vec3 scale n 1 0 vec3 scale n 1 validv nl if depth 3 return obj e let f new vec3 obj c x obj c y obj c z validv f let p f x f y f x f z f x f y f z f y f z max refl shell approximation method for calculationg local ambient occlusion if obj refl REFL DIFF hemispheres 10 100 1000 let light 0 0 let hs 10 100 1000 let hf 0 1 0 5 1 0 for let h 0 h hs length h local ambient occlusion let nr 5 let sum 0 0 let delt hs h let dr 0 5 for let k 0 k nr k randomize nl hemisphere let nh vec3 add nl new vec3 Math random 2 1 dr Math random 2 1 dr Math random 2 1 dr nh vec3 norm nh let ray_ new Ray x nh let o_ ray ray_ t 0 id 0 if intersect o_ o_ t 1 0 if o_ t delt o_ t delt if o_ t 0 0 o_ t 0 0 sum o_ t sum nr sum 1 0 delt hf h light sum end hr return vec3 scale obj c light Full Monte carlo calculation global illumiation if obj refl REFL DIFF Ideal DIFFUSE reflection let r1 2 M_PI erand48 Xi let r2 erand48 Xi let r2s sqrt r2 let w nl let refv fabs w x 1 new vec3 0 1 new vec3 1 let u vec3 cross refv w u vec3 norm u let v vec3 cross w u validv v let aa11 vec3 scale u cos r1 r2s validv aa11 let aa22 vec3 scale v sin r1 r2s validv aa22 let aa33 vec3 scale w sqrt 1 r2 validv aa33 let aabb vec3 add3 aa11 aa22 aa33 validv aabb let d vec3 norm aabb validv d let tt trace new Ray x d depth Xi validv tt let res0 vec3 add obj e vec3 mult f tt console log res0 res0 return res0 Reflection calculation shiny surfaces reflect what they re looking at else if obj refl REFL SPEC Ideal SPECULAR reflection let gg vec3 sub ray d vec3 scale n 2 vec3 dot n ray d let tt trace new Ray x gg depth Xi let res2 vec3 add obj e vec3 mult f tt console log res2 res2 validv res2 return res2 function main let w 256 256 1024 let h 256 256 768 let samps 4 0 samples let cam new Ray new vec3 50 52 295 6 vec3 norm new vec3 0 0 042612 1 cam pos dir let cx new vec3 w 5135 h let cy vec3 scale vec3 norm vec3 cross cx cam d 0 5135 let c Array from Array w h map return vec3 for let y 0 y h y Loop over image rows fprintf stderr rRendering d spp 5 2f samps 4 100 y h 1 for let x 0 x w x Loop cols let Xi new Array 3 0 0 y y y for let sy 0 sy 2 sy 2x2 subpixel rows let i h y 1 w x for let sx 0 sx 2 sx 2x2 subpixel cols let r new vec3 for let s 0 s samps s let r1 2 erand48 Xi dx r1 1 sqrt r1 1 1 sqrt 2 r1 let r2 2 erand48 Xi dy r2 1 sqrt r2 1 1 sqrt 2 r2 dx 0 5 dy 0 5 let d vec3 add3 vec3 scale cx sx 5 dx 2 x w 5 vec3 scale cy sy 5 dy 2 y h 5 cam d let cd2 vec3 add cam o vec3 scale d 140 let rr2 trace new Ray cd2 vec3 norm d 0 Xi c i vec3 add rr2 c i let t2 vec3 scale rr2 1 0 samps r vec3 add r t2 s Camera rays are pushed forward to start in interior c i vec3 add c i vec3 scale vec3 clamp r x clamp r y clamp r z 0 25 return return sx sy x y let canvas document createElement canvas document body appendChild canvas canvas width w canvas height h let context2d canvas getContext 2d let image_data context2d getImageData 0 0 w h raw_data image_data data for let x 0 x w x for let y 0 y h y let i x y w image_data data i 4 0 toInt c i x image_data data i 4 1 toInt c i y image_data data i 4 2 toInt c i z image_data data i 4 3 255 context2d putImageData image_data 0 0 console log finished render main console log ready
dv n let nl vec3 dot n ray d 0 vec3 scale n 1 0 vec3 scale n 1 validv nl if depth 3 return obj e let f new vec3 obj c x obj c y obj c z validv f let p f x f y f x f z f x f y f z f y f z max refl shell approximation method for calculationg local ambient occlusion if obj refl REFL DIFF hemispheres 10 100 1000 let light 0 0 let hs 10 100 1000 let hf 0 1 0 5 1 0 for let h 0 h hs length h local ambient occlusion let nr 5 let sum 0 0 let delt hs h let dr 0 5 for let k 0 k nr k randomize nl hemisphere let nh vec3 add nl new vec3 Math random 2 1 dr Math random 2 1 dr Math random 2 1 dr nh vec3 norm nh let ray_ new Ray x nh let o_ ray ray_ t 0 id 0 if intersect o_ o_ t 1 0 if o_ t delt o_ t delt if o_ t 0 0 o_ t 0 0 sum o_ t sum nr sum 1 0 delt hf h light sum end hr return vec3 scale obj c light Full Monte carlo calculation global illumiation if obj refl REFL DIFF Ideal DIFFUSE reflection let r1 2 M_PI erand48 Xi let r2 erand48 Xi let r2s sqrt r2 let w nl let refv fabs w x 1 new vec3 0 1 new vec3 1 let u vec3 cross refv w u vec3 norm u let v vec3 cross w u validv v let aa11 vec3 scale u cos r1 r2s validv aa11 let aa22 vec3 scale v sin r1 r2s validv aa22 let aa33 vec3 scale w sqrt 1 r2 validv aa33 let aabb vec3 add3 aa11 aa22 aa33 validv aabb let d vec3 norm aabb validv d let tt trace new Ray x d depth Xi validv tt let res0 vec3 add obj e vec3 mult f tt console log res0 res0 return res0 Reflection calculation shiny surfaces reflect what they re looking at else if obj refl REFL SPEC Ideal SPECULAR reflection let gg vec3 sub ray d vec3 scale n 2 vec3 dot n ray d let tt trace new Ray x gg depth Xi let res2 vec3 add obj e vec3 mult f tt console log res2 res2 validv res2 return res2 function main let w 256 256 1024 let h 256 256 768 let samps 4 0 samples let cam new Ray new vec3 50 52 295 6 vec3 norm new vec3 0 0 042612 1 cam pos dir let cx new vec3 w 5135 h let cy vec3 scale vec3 norm vec3 cross cx cam d 0 5135 let c Array from Array w h map return vec3 for let y 0 y h y Loop over image rows fprintf stderr rRendering d spp 5 2f samps 4 100 y h 1 for let x 0 x w x Loop cols let Xi new Array 3 0 0 y y y for let sy 0 sy 2 sy 2x2 subpixel rows let i h y 1 w x for let sx 0 sx 2 sx 2x2 subpixel cols let r new vec3 for let s 0 s samps s let r1 2 erand48 Xi dx r1 1 sqrt r1 1 1 sqrt 2 r1 let r2 2 erand48 Xi dy r2 1 sqrt r2 1 1 sqrt 2 r2 dx 0 5 dy 0 5 let d vec3 add3 vec3 scale cx sx 5 dx 2 x w 5 vec3 scale cy sy 5 dy 2 y h 5 cam d let cd2 vec3 add cam o vec3 scale d 140 let rr2 trace new Ray cd2 vec3 norm d 0 Xi c i vec3 add rr2 c i let t2 vec3 scale rr2 1 0 samps r vec3 add r t2 s Camera rays are pushed forward to start in interior c i vec3 add c i vec3 scale vec3 clamp r x clamp r y clamp r z 0 25 return return sx sy x y let canvas document createElement canvas document body appendChild canvas canvas width w canvas height h let context2d canvas getContext 2d let image_data context2d getImageData 0 0 w h raw_data image_data data for let x 0 x w x for let y 0 y h y let i x y w image_data data i 4 0 toInt c i x image_data data i 4 1 toInt c i y image_data data i 4 2 toInt c i z image_data data i 4 3 255 context2d putImageData image_data 0 0 console log finished render main console log ready