Create a small raytracer able to render a small set of geometrical objects, like spheres, planes and cylinder.

Table of Contents

• Introduction
• Features and strategy
  • Mandatory
  • Special features
    • Computationnal acceleration
    • Textures and bumpmaps
    • Anti-aliasing
• Use
  • Compile and use
  • Configure
  • From inside:
• Some pictures
• Thanks

The aim of that project was to create a small raytracer, able to render various of simple sets of scenes. Thus we chose to decouple the process as much as we could, to make it more modular and easy to improve.

flowchart TB
   prog(miniRT)-->parse(parsing)
   prog-->render(rendering computations)
   prog-->gui(user interface)
   render-->inter(ray intersection)
   render-->light(light contribution)
   render-->color(output color)
   inter-.->light-.->color

This architecture allowed us to be really modular: adding a new geometric object leads only to add a new description of the intersection with the ray an the related properties of that intersection.

We used a Phong reflexion model, allowing an easy computation, with a still realistic rendering. Thank to that, we were able to put a mask on the camera/the light, to determine with really few computation if a given ray would have a chance to intersect a given object, and thus spare the intersection calculation time.

Even we had tools to read xpm images, we prefered to create our own image parser. Thus, we learned to parse and read as underset of the tiff format images, which has the posibility to store uncompressed images. This was done using the standard description and has been the opportunity to learn more about how to parse a binary file and how such standard can work.

With that new knowledge, we choosed to add the possibility to export the current rendering image as a tiff¹.

This was archived by sending 100 rays per pixel, with a randomized distribution over that pixel.

You have a bundle of 3 version of the project, but I still recommand to use either the bonus version (complete and fast) or the antialiasing version (complete and slow).

make -j bonus abonus

Then launch the program as

./miniRT_bonus [filename.rt]
./demo/demo.sh

I will describe here only the bonus and the abonus versions as they use the same format and allow more flexibility.

Any object has 3 optionnal parameters describing the texture (replacing the color), the bumpmap and the checkboard status.

from demo/cylinder.rt²:

ca 0,0,0     1,0,0  70

A           0.2    255,255,255
l 0,-3,9    1.0    255,255,255

pl 0,0,-2   0,0,1  255,255,255

cy 5,2,0 1,0,0.2  1 1 255,255,255 0 0
hb 7,-3,4 0,0,1 1  1 255,255,255 0 0 1
cy 4,0,-2 -0.2,0,1 2 2 255,255,255 0 0 1

_te_ ressources/textures/earthmap.tiff
_bm_ ressources/bumpmaps/earthbump1k.tiff

The interactions are mapped on an qwerty keyboard. You can run this program, as you would have a camera on your shoulder an be able to go around in the scene, thus you are able to:

• move in the camera plane with the arrow keys
• zoom in/out with zx
• look around with wasd
• rotate with qe
• all this can be done with the mouse: left clic -> camera pitch / right clic -> camera move / scroll -> zoom
• esc to quit

A really nice feature is the menu (tab key) you can choose an element/a propery with the arrow keys, change it by hitting the number bar (not the numpad), change the element category with Ctrl+l/r arrowkey. Just kit enter to validate and tab to escape the menu.

Try the colors:

Without/with antialiasing:

Special thanks to JamesGarrigou for his really nice parsing and the amazing menu he added to be able to change any property while the program is rendering.