T-RayX

A NIM Raytracing Library.

:t-rex: Overview

T-RayX: a Nim library aimed to generate a photorealistic image.

The project has been developed during the course Numerical techniques for photorealistic image generation held by Prof. Maurizio Tomasi at Università degli Studi di Milano (A.Y. 2021/2022)

The main functionality of this library is to generate photorealistic images from input files that describe a scene. (See more details here). With T-RayX you are also able to convert PFM files to PNG using the pfm2png command.

:desktop_computer: System Requirements

T-RayX works on Linux, MacOSX and Windows (not so sure) machine.

For a proper use of the library you need: - Nim version required: 1.6.4 - Nimble package manager - simplepng: use nimble install simplepng to install it. - docopt: use nimble install docopt to install it. - ffmpeg and GNU parallel just for the animations (see scripts folder).

:wrench: Download and build

You can download the latest stable release here, and unpack it bash tar -xvf /path/to/tar #or zip file -C /path/to/your/directory or if you want, you can clone this repository bash git clone https://github.com/teob97/T-RayX.git

To generate the executable file, use:

nimble build -d:release

It is also possible to install T-RayX using nimble package menager:

nimble intall trayx

In this case the program is automaticaly compiled and it is possible to use it via terminal simply with trayx without ./

:rocket: Usage

You can run the following command to visualize through the CLI all the possible procedures:

./trayx --help

:small_orange_diamond: render

To run the render, use:

./trayx render <SCENE_FILE.txt> <width> <height> [options]

To see all the possible options use ./trayx --help.

The input file SCENE_FILE.txt must contain the detailed description of the scene that has to be rendered. See the next section

:small_orange_diamond: pfm2png

Convert pfm file in png image using:

./trayx pfm2png <file.pfm> <alpha> <gamma> <output.png>

It is necessary to set specific values for alpha and gamma parameters.

:small_orange_diamond: demo

To run the demo, use:

./trayx demo

This will produce the following 960x540 image:

:page_facing_up: Input file format

To describe the scene that has to be rendered it is necessary to create a .txt file and use a specific syntax. Below are all the keywords that can be used within the input file:

First thing first it is necessary to define a camera, use the following syntax:

camera(CAMERA_TYPE, TRANSFORMATION, aspectRatio:float, distance:float)

where aspectRatio is a float representing the ration between the width and the height (expressed in # of pixel) of the image; distance is a float representing the distance of the camera from the screen.

To define a space vector or a color it is necessary to specify three values:

[x:float, y:float, z:float] # This is a vector representing a 3D position or a direction
<r:float, g:float, b:float> # This is a vector representing a RGB color

The first vectors are used to define translation. Here are the ways to define the various possible transformations:

identity # Use this if you don't want a transformation
translation([x,y,z])
scaling([x,y,z])
rotation_x(rotation_angle:float) # Define a rotation around the x axis
rotation_y(rotation_angle:float) # Define a rotation around the y axis
rotation_z(rotation_angle:float) # Define a rotation around the z axis

To define a pigment use the RGB vectors:

uniform(<r,g,b>)
chekered(<r1,g1,b1>, <r2,g2,b2>, n_step:int)
image(image_PATH:string)

To define the material of the shapes that will be rendered it is necessary to use the correct BDRF:

material NAME(diffuse(PIGMENT), uniform(<r,g,b>)) # Diffuse brdf, the second pigment represent the emitted radiance.
material NAME(specular(PIGMENT), uniform(<0,0,0>)) # Specural brdf

To define a shape use this syntax:

FIGURE (MATERIAL, TRANSFORMATION)

In pointlight render to define a light source use:

light ([x,y,z], <r,g,b>, radius:float)

It is also possible to define float variables:

float NAME(value:float)

You can find many examples in the examples folder!

:book: Documentation

A complete documentation with all the procedures and the data structures is aviable at this link

:police_car: License

The code is released under a GPL-3.0 license. See the file LICENSE

:sunglasses: Examples

Example 1 (pfm2png)

Run:

$ ./trayx pfm2png examples/pfm2png/lawn.pbm 0.6 1.45 examples/pfm2png/lawn_a0.6-gamma1.45.png

in order to create the following image:

It is possible to tune the parameters alpha and gamma.

| | :--:|:--:|:--:| alpha = 0.3 | alpha = 0.6 | alpha = 0.9

Example 2 (render)

Use the following command to produce the scene described here:

./trayx render examples/render/example1.txt 400 400 --output=examples/render/example1.png --luminosity=0.4 --gamma=2 --samplePerPixel=9

Use the following command to produce the scene described here:

./trayx render examples/render/example2.txt 400 400 --output=examples/render/example2.png --luminosity=0.2 --gamma=2 --maxDepth=3 --samplePerPixel=9

Use the following command to produce the scene described here:

./trayx render examples/render/example3.txt 400 400 --output=examples/render/example3.png --samplePerPixel=9

| | :--:|:--:|:--:| example 1 | example 2 | example 3

You can also try to generate more artistic images. For the following image, we took inspiration from an artistic work by Jeff Koons.