List of Implemented Features

Basic Ray Generation

• (1) Generate at ray for each pixel

Ray-Primitive Intersection

• (1) Intersect a ray with a sphere
• (1) Intersect a ray with an axis-aligned box
• (2) Intersect a ray with a polygonal mesh
• (1) Intersect a ray with an n-sided polygonal mesh
• (2) Intersect a ray with an axis-aligned cylinder
• (2) Intersect a ray with an axis-aligned cone

Ray-Scene Intersection

• (1) Intersect a ray with a scene
• (1) Handle scene traversals with modeling transformations
• (1) Accelerate ray-scene intersections with bounding box checks
• (1) Accelerate ray-scene intersections by visiting nodes front to back

Illumination

• (2) Phong illumination

Shadows

• (1) Shadow rays

Global Illumination

• (2) Specular reflection
• (1) Transmission
• (2) Refraction

Input

• (1) Make an interesting scene
• (1) Movie

Art contest

• (1) Art contest submission

Demonstration of Implemented Features

Ray-Primitive intersection

sphere.scn	tri.scn
quadmesh.scn
ico.scn	teapot.scn
box1.scn	box2.scn
cylinder1.scn	cylinder2.scn
cone1.scn	cone2.scn
Ray-mesh intersection works with all kinds of meshes, not just triangle meshes, which is worth an extra point (see Piazzza). Cone and cylinder I just did some math to figure out the intersection t values. Sphere, mesh and box intersections are a little sneakier if you care to look at the code. Oh, one more thing: some sample scene files I found specify boxes with their z components reversed, eg (1 1 -1) (1 1 1). This is an error on behalf of the person who wrote the scene (It's not specified anywhere that we have to handle this.) so be aware that if a box renders improperly, reversing the z components to their proper order WILL fix it. This modification had to be made for the green box in mixedprimitives.

Ray-Scene intersection

fourspheres.scn	sixtriangles.scn
mixedprimitives1.scn	mixedprimitives2.scn
This part of the assignment seemed very straightforward. A simple depth first search into the scene graph to render objects, augmented with bbox checks was used.

Phong Illumination

diffuse.scn	specular.scn	shininess.scn
dirlight1.scn	pointlight1.scn	spotlight1.scn
dirlight2.scn	pointlight2.scn	spotlight2.scn
This part of the assignment was also pretty straightforward. Simple use of Phong illumination calculations.

Shadows

hardshadow.scn

Shadows were done by casting a new ray from the intersection point in the direction of the light and only doing a lighting calculation if nothing intersected the shadow ray.

Specular Reflection

-max_depth 0	-max_depth 1	-max_depth 2
specular.scn
-max_depth 0	-max_depth 1	-max_depth 2
stilllife.scn
This was similar to shadow rays except the lighting calculation for each specular ray cast was carried up recursively and added to the initial intersection.

Transmission

-max_depth 0	-max_depth 1	-max_depth 2
-max_depth 2
transmission.scn   refraction2.scn
Similar to specular reflection but now the rays go out on the other side of the primitive.

Refraction

-max_depth 2

refraction2.scn

Similar to perfect transmission but the ray is changed by an angle before being sent into the primitive. I was experiencing some bugs with noise on some test cases but it appears to be fixed now. If this appears to not work with your script, please look at the code-- I think my implimentation is worth full credit but I should get at least half credit for this feature if you find it fails on something.

Handle scene traversals with modeling transformations

mixedprimitives3.scn	transform.scn
This was fairly straighforward-- apply transformations to the ray as we descend into the scene graph.

Ray Intersection Acceleration

No acceleration (> 5min)
Node bounding box checks (3m 28s)	Front-to-back order (3m 15s)
No acceleration (> 5min)
Node bounding box checks (48.677s)	Front-to-back order (38.544s)
stack.scn
My implimentation runs with all of the optimizations enabled. The last time I included extra flags on an assignment I was docked eight points because my code became incompatible with the test script so I haven't included any here but if you'd like to verify these times, I've made it very easy to comment things out in the code.

Art Contest Submission

This is my interesting scene and my movie (in gif form)

dynamic.scn.scn

Interesting blooper

This was supposed to be a cylinder..

Feedback

How long did you spend on this assignment?

Not too long.
 

Was it too hard, too easy, or just right?

It was pretty good.
 

What was the best part of the assignment?

Specular reflection (It worked the first time.)
 

What was the worst part of the assignment?

Bounding box acceleration-- it lead to a lot of subtle bugs.
 

How could it be improved for next year?

Maybe eliminate the menu format.