Area Light acne from the box (light fixture)

Hello Steve,

The trick to implementing "shadow: false" is to change the shadow intersection routine. When intersecting the shadow ray with all objects, you need to ignore any objects that have opted out of shadows (that is, they've set "shadow: false"). In other words, instead of simply returning true if an intersection is found, you need to walk the list of intersections and only return true if any of them actually cast shadows ("shadow: true").

I hope that makes sense! Let me know if you're still not sure how this needs to work.

- Jamis

Multiplying a colour by light intensity 1.0 would leave the colour unchanged, multiplying it by 1.5 would grow it 50%, very easily finding yourself in a situation where final colour values became burnt-out white (>= 1).....

The lighting(...) function computes the final colour, at one point by multiplying 'effective_colour' by 'light_intensity'... If the intensity values are >1, the resultant values will expand, perhaps beyond 1.0 for any or all of the component r/g/b values...

It also depends on how you've coded your colour sub-system. In the part, perhaps, that converts normalised rgb values (0 <= v <= 1) to rgb "proper" (0-255 for each component - best to think of it as 0.0 to 255.0), your code should "cap" values above 1: if (v > 1.0) v = 1.0; if (v <= 0.0) v = 0.0;

Then, to get the RGB valuse, it's simply:

col_val = Math.floor(255 * v);

If you use a graphics library that accepts normalised rgb tuples (0 <= v <= 1), that library should cap them transparently.

If the appropriate subsystem didn't, surely it would either a) show no indication of the bug in the output image (<0 would be black, >1 would be white), or b) your program would crash...

You may find fundamental logic errors in your code, and in that case, most likely images would be black, or burnt-out white whenever/wherever you mixed multiple colours, or lighting(...) multiplied the internal colour value by an intensity tuple with values > 1.0.....



Did that help, or was it a useless answer??