new Cheap Torus Alternative demo!

Author: erichlof

README.md

@@ -65,6 +65,8 @@ For comparison, here is a real photograph of the original Cornell Box vs. a rend
 
 * [Transforming Quadric Geometry Demo](https://erichlof.github.io/THREE.js-PathTracing-Renderer/Transforming_Quadric_Geometry_Showcase.html) Using the game engine version of the three.js path tracer, this demo shows how to create multiple objects (a bunch of 'THREE.Object3d()'s, each with its own transform) on the JavaScript side when initializing three.js, and then send the objects over to the GPU for realtime pathtracing.  The nice thing about having my pathtracer sitting on top of three.js is that I can use its built-in transformations such as Translate, Rotate, and Scale.  Since these shapes are all quadrics made from different parameters, I also included clipping parameters so you can have partial shapes and can even animate the cutting process! *Note: this demo may take several seconds to compile* <br>
 
+![CheapTorus2](https://github.com/erichlof/THREE.js-PathTracing-Renderer/assets/3434843/d80aec3f-ff9e-4833-8ff3-699aed65ff3b)
+
 * [Cheap Torus Alternative Demo](https://erichlof.github.io/THREE.js-PathTracing-Renderer/Cheap_Torus.html) Introducing the Cheap Torus, my custom approximation to the beautiful Torus shape.  Historically, the Torus has always been difficult and expensive to ray trace, because it is a quartic (degree 4) shape which requires you to solve for the roots of a quartic equation.  I've tried many different quartic solvers out there and they are either too finnicky to use and get looking right, or too expensive to efficiently run on normal consumer hardware and mobile.  And then after doing all that work, you still get rendering artifacts like gaps and thin cracks at larger scales, due to limited GPU shader float precision.  So, determined to efficiently render a Torus that would be air-tight at all scales, I set out on a journey to find a better solution.  Along this rabbit hole (ha), I discovered a cool trick of combining 2 simple quadric shapes (only degree 2), namely the Hyperboloid (hourglass) and the truncated Sphere (both top and bottom removed).  When these 2 simple shapes are combined in just the right way, we get a very close approximation to the Torus, free of gap artifacts at all scales and very fast to render.  Now we can finally have multiple Torii all over our scenes without worrying about precision artifacts or performance costs - enjoy!  <br> <br>
 
 <h3>Constructive Solid Geometry(CSG) Demos</h3>