Creating Bounding Box Functionality

I am currently working through the bonus chapter on bounding boxes. For the test Scenario: A group has a bounding box that contains its children I am almost getting the correct result. Here are the results I'm getting:


b.max = tuple {x: 4, y: 7, z: -1, w: 1}
b.min = tuple {x: -4.5, y: -3, z: -5, w: 1}

As you can see, it is only out on the .max z-component. It should be 4.5, not -1. I haven't refactored my code yet, so I won't upload it to my github for perusal (EDIT: See later post for the link and description), but I have sensibly and correctly implemented according to the instructions, and so far every test I've needed to pass, I've passed. The odd thing is, it's only the z-component on 1 of the points. Specifically I can tell you the transform(bounding_box, matrix) function is not in error - I essentially cut-and-pasted the pseudo-code. Here is my bounding_box.addBB() (add bounding box) function:

BB.addBB = function(b) {

this.min=point(window.min(this.min.x,b.min.x), window.min(this.min.y,b.min.y), window.min(this.min.z,b.min.z))
this.max=point(window.max(this.max.x,b.max.x), window.max(this.max.y,b.max.y), window.max(this.max.z,b.max.z))
};

And here are my min() and max() functions:

function max() {

var val = -Infinity;
for (var a = 0; a < arguments.length; a++)
if (arguments[a] > val)
val = arguments[a]

return val
}

function min() {

var val = Infinity;
for (var a = 0; a < arguments.length; a++)
if (arguments[a] < val)
val = arguments[a]

return val
}

Clearly, it is implemented in Javascript. Any input would be appreciated!

Just to be sure, here is my bounding_box.transform() function:

BB.transform = function(m) {

var p = []
p.push(this.min)
p.push(point(this.min.x, this.min.y, this.max.z))
p.push(point(this.min.x, this.max.y, this.min.z))
p.push(point(this.min.x, this.max.y, this.max.z))
p.push(point(this.max.x, this.min.y, this.min.z))
p.push(point(this.max.x, this.min.y, this.max.z))
p.push(point(this.max.x, this.max.y, this.min.z))
p.push(this.max)

var new_bbox = new BB(), res

for (var i = 0; i < 8 /* p.length */; i++) {

res = multiply_matrix_by_tuple(m,p[i])
new_bbox.addP(res)
}

return new_bbox

};

I have relented and uploaded my current codebase onto GitHub. It can be found here: github.com/leeodea/rt-dt

Please note, the vast majority of what you are looking for is in the file "rt.p+e.js" (which stands for projectile+environment). It is where the implementation of my Shapes and Groups is. Also, "rt.tests.js" has 2 tests as it's last 2 functions. The last one, bb_test_1() is the test we are currently discussing. (Note, many older tests are now broken - it doesn't matter).

Load "raytracer.html" into your browser, open up the console, and type bb_test_1() to run the test. The debugger will kick in, and you can peek at box.min and box.max.

My codebase is not at all refactored, so sorry about that, but it is written/formatted for readability. (Final note: Don't load object file "FinalBaseMesh.obj" and then click "render obj!", it takes hours.)

Awesome, thanks bro! Test passing. Now onto implementing BVH, see if I can get the preview render time down from 6-odd hours.

Good job !

Now I think you can improve the ray transform function:

function transform(r_in, m) { // p69

 //var r = copyObj(r_in);
 var r = JSON.parse(JSON.stringify(r_in))

 var res = multiply_matrix_by_tuple(m, r.origin);
 var res2 = multiply_matrix_by_tuple(m, r.direction);

 r.origin = res;
 r.direction = res2;

 return r;
}