Raymond

Raymond is a simple raytracer written in C++.

Features

• JSON-based scenes: Generate images by defining a scene in a JSON file.
• Basic Geometry: Generate scenes with Spheres, Boxes, and Quads.
• Multiple Materials: Apply materials like Lambertian, Metal, Dielectric, and DiffuseLight.
• Anti-aliasing: Smoothes jagged edges on curves and diagonal lines.
• Depth control: Control how many times the ray bounces.
• Parallelized using OpenMP: Rendering of the image is parallelized over multiple threads.
• Multiple output formats supported: Supports jpg, png, and ppm image formats.

Images generated by raymond

Scene file for this: ./example_scenes/cornell_box/cornell_box_scene.json

Scene file for this: ./example_scenes/earth/earth_scene.json

Scene file for this: ./example_scenes/perlin/perlin_output.png

Usage

• Clone the repo

git clone https://github.com/nishantHolla/raymond
cd raymond

• Build the project

make release
cd out

• Run raymond

./raymond input_scene.json output_image.png

Creating a scene file

1. Create a new input_scene.json file.
2. Add a camera section to define the properties of the camera in the scene.

{
  "camera": {
    "aspect_ratio": 1.77778,
    "image_width": 1200,
    "samples_per_pixel": 300,
    "max_depth": 500,
    "background": [0.1, 0.1, 0.3],
    "vfov": 60,
    "lookfrom": [0, 0, -9],
    "lookat": [0, 0, 0],
    "vup": [0, 1, 0],
    "defocus_angle": 0
  },
}

• aspect_ratio: Ratio of the width of the output image to the height
• image_width: Width of the output image in pixels
• samples_per_pixel: Number of samples to take for each pixel (Higher the number, slower the render)
• max_depth: Maximum number of bounces for each ray (Higher the number, slower the render)
• background: [r, g, b] color value of the background of the scene
• vfov: "Vertical field of view" — how zoomed in or out the camera is
• lookfrom: [x, y, z] vector position of the camera in 3D space
• lookat: [x, y, z] vector position of where the camera should look at in 3D space
• vup: [x, y, z] vector of "up" for the camera
• defocus_angle: Used for depth of field blur — keep at 0 for now.

3. Define all the textures you will need for the scene and give them a unique name that can be used later to apply the textures.

{
  "textures": {
    "earth_texture": {
      "type": "ImageTexture",
      "source": "./earthmap.jpg"
    },

    "space_texture": {
      "type": "ImageTexture",
      "source": "./space.jpg"
    }
  },
}

• Here, earth_texture and space_texture are unique names assigned to the textures.
• Each texture has a type which can be ImageTexture, SolidColor, NoiseTexture, or CheckerTexture.
• Look at ./example_scenes/ to know about how to setup these textures.
• If you define an ImageTexture make sure that the path to the image is relative to the executable.

4. Define all the materials you will need for the scene and give them a unique name that can be used later to apply the materials.

{
  "materials": {
    "earth_material": {
      "type": "Lambertian",
      "texture": "earth_texture"
    },

    "space_material": {
      "type": "Lambertian",
      "texture": "space_texture"
    },

    "light_material": {
      "type": "DiffuseLight",
      "color": [8, 8, 7]
    }
  },
}

• Here, earth_material, space_material, and light_material are unique names assigned to the materials.
• Each material has a type which can be Lambertian, Metal, Dielectric, or DiffuseLight.
• Look at ./example_scenes/ to know about how to setup these materials.

5. Define all the objects you want to place in the scene and give them a unique name.

{
  "entities": {
    "earth": {
      "type": "Sphere",
      "center": [0, 0, 0],
      "radius": 2,
      "material": "earth_material"
    },

    "space": {
      "type": "Quad",
      "center": [0, 0, 2],
      "horizontal": [30, 0, 0],
      "vertical": [0, 15, 0],
      "material": "space_material"
    },

    "light": {
      "type": "Sphere",
      "center": [-150, 0, -180],
      "radius": 150,
      "material": "light_material"
    }
  }
}

• Here, earth, space, and light are unique names assigned to the entities (objects).
• Each entity has a type which can be Sphere, Quad, or Box.
• Each entity should be assigned a material that must be the name of one of the materials defined in the materials section
• Look at ./example_scenes/ to know about how to setup these materials.

6. You should end up with a JSON that looks like this
7. Pass this JSON as the argument to raymond and it should render the scene as you specified.

Reference

• raytracing in one weekend series
• stb
• nlohmann/json