miniRT

Resources:

• (https://www.scratchapixel.com/index.html)
• (https://learnopengl.com/Lighting/Basic-Lighting)
• (https://www.mvps.org/directx/articles/spheremap.htm)
• (http://raytracerchallenge.com/optional/texture-mapping.html)
• (https://math.stackexchange.com/questions/2305792/3d-projection-on-a-2d-plane-weak-maths-ressources)
• (http://www.illusioncatalyst.com/notes_files/mathematics/line_sphere_intersection.php);
• (https://www.cse.psu.edu/~rtc12/CSE486/lecture12.pdf)

introdution

In this exercice, we have to write a basic raytracer in C. We need to support at least the following shapes:

• sphere
• plane
• cylinder

parsing

We need to be able to parse files that contain the description of the scene we need to render.

The grammar is roughly as follows:

file         := {line}
line         := ( ambient | camera | light | sphere | plane | cylinder | cone ) line_end

ambient      := "a"  ratio color
camera       := "c"  position unitvector fov
light        := "l"  position ratio color

sphere       := "sp" position diameter color [optional]
plane        := "pl" position unitvector color [optional]
cylinder     := "cy" position unitvector diameter height color [optional]
cone         := "co" position unitvector diameter height angle color [optional]

optional        := [texture] [bmp] [normal_map] [checkerboard]

checkerboard := "checkerboard"

texture      := "texture:"path
bmp          := "bmp:"path
normal_map   := "normal_map:"path

path         := "relative_path/to/file.xpm"
line_end     := lf | crlf | eof

Some extra validation needs to be done after verifying the grammar, for example, there can only be one camera in the scene.

Here is an example of a valid scene containing 2 spheres:

A	0.2									255,255,255
C	0,0,0 0,0,1	70
L	-40,0,30		0.9					255,255,255
sp	10,0,51			10					250,100,200
sp	0,0,42			20					255,0,0

rendering

The raytracing technique consists in computing rays starting from the camera pinhole going through the pixels of the image we're rendering. By computing the color of the object that ray intersects with, we get the color of that corresponding pixel. This technique allows us to realistically compute shadows and reflection.

lighting

In this project, we use the ambiant, diffuse and specular lighting model. Specular reflection:

• (https://registry.khronos.org/OpenGL-Refpages/gl4/html/reflect.xhtml)

textures / bump maps / normal maps

UI

In this project we are required to be able to move all objects in the scene. This means we need to find a way for the user to interact with the objects and change their coordinates.

maths

In this project, we use a lot of operation between vectors.