Constructive Solid Geometry

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Difficulty

Reading material

def scene_at(now)
{
  var camera = Cameras.perspective( [ "eye": pos(0,0,10),
                                      "look_at": pos(0,0,0) ] )

  var material = Materials.uniform( [ "ambient": Colors.white() * 0.1,
                                      "diffuse": Colors.white() * 0.8,
                                      "specular": Colors.white(),
                                      "specular_exponent": 100,
                                      "reflectivity": 0,
                                      "transparency": 0,
                                      "refractive_index": 0 ] )

  var angle = Animations.animate(degrees(0), degrees(360), seconds(5))[now]

  var csg1 = translate(vec(0,3,0), csg_union( [ translate(vec(0,0,-0.5), sphere()), translate(vec(0,0,0.5), sphere()) ] ))
  var csg2 = csg_intersection( translate(vec(0,0,-0.5), sphere()), translate(vec(0,0,0.5), sphere()) )
  var csg3 = translate(vec(0,-3,0), csg_difference( translate(vec(0,0,-0.5), sphere()), translate(vec(0,0,0.5), sphere()) ))

  var root = decorate(material, union([
  	rotate_around_y(angle, csg1),
  	rotate_around_y(angle, csg2),
  	rotate_around_y(angle, csg3)
  ]))

  var lights = [ Lights.omnidirectional( pos(0,0,5), Colors.white() ) ]

  create_scene(camera, root, lights)
}


var raytracer   = Raytracers.v6()
var renderer    = Renderers.standard( [ "width": 500,
                                        "height": 500,
                                        "sampler": Samplers.multijittered(2),
                                        "ray_tracer": raytracer ] )

pipeline( scene_animation(scene_at, seconds(5)),
          [ Pipeline.animation(30),
            Pipeline.renderer(renderer),
            Pipeline.studio() ] )

Shapes can be constructed by combining simpler shapes in different ways:

Union

union

Difference

difference

Intersection

intersection

The code for union is already given. Use it as a template to define the two other operations. Note however that while the union operation is defined as taking a list of children, intersection and difference can limit themselves to exactly two children.

1. Intersection

Create files primitives/csg-intersection-primitive.cpp and primitives/csg-intersection-primitive.h.
Write the necessary code.
Provide a factory function with signature Primitive csg_intersection(Primitive, Primitive).
Expose this operation as csg_intersection to the scripting language.

2. Difference

Create files primitives/csg-difference-primitive.cpp and primitives/csg-difference-primitive.h.
Write the necessary code.
Provide a factory function with signature Primitive csg_difference(Primitive, Primitive).
Expose this operation as csg_intersection to the scripting language.

3. Evaluation

TODO