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CPSC 4050/6050 Spring 2021
Project 1
due date: February 26 upload to handin
Summary
For this project you will write, compile, and execute C++ code to raytrace a
simple 3D scene and write the image to a simple ascii image file. The output
image will be in ppm format. You will put all of the code and the output image
in a folder, zip it into a single zip file, and upload it to . Your submission will be
compiled and executed on School of Computing linux computers. Compilation
will be accomplished via make. It is very much in your interest to make sure
your code compiles and runs in that computing environment.
1 Description for All Students
As we discussed in class, ray tracing a simple scene requires the following elements:
• A camera
• An Image Plane (a collection of pixels in a rectangular arrangement)
• A Ray (for each pixel of the image plane)
• One or more 3D objects (plane and sphere), with material properties (e.g.
color)
• A Scene, which is a container of 3D objects, such as planes and spheres.
• A raytracing function
CPSC 6050 students will also need:
• One or more lights
To create your ray tracer, you must create a separate C++ class for each of
the following concepts:
1
Class Class Data Class Methods
Camera
• position
• view direction
• up direction
• field-of-view
• aspect ratio
Vector view(float x, float y) const;
ImagePlane
• Nx, N y
• Color* data
• Color get(int i, int j) const;
• void set(int i, int j, const Color& C);
Ray
• position
• direction
• const Vector& get position() const;
• const Vector get direction() const;
Sphere
• position
• radius
• float intersection(const Ray& r) const;
• const Color get color() const;
Plane
• position
• normal direction
• float intersection(const Ray& r) const;
• const Color get color() const;
The ray tracing function is not a class:
Color Trace(const Ray& r, const Scene& s);
This function tests the intersections of the input Ray with each object in the
Scene container. If any of the objects are intersected by the ray, the Trace
function returns the color of the object with the closest intersection. If no
objects are intersected, it returns black.
A ray-trace renderer performs the following 4 steps for each pixel of the
image plane:
- Call the camera’s view(x,y) method with the x,y for the given pixel,
returning the pixel direction vector. - Initialize a ray with the position of the camera and the pixel direction.
- Call the Trace function, which returns a color following the outcome of
its intersection tests (as described above). - Set the color of the pixel to be the color returned by Trace.
You must write C++ code for each of the classes in the above table. The
classes may have more data and/or methods beyond what is listed in the table,
2
but those data and methods must be in the declaration and implementation of
each of the classes. You must create separate header and implementation files for
each class, i.e. you will have at least 5 header files and at least 5 implementation
files, with names Camera.h, Camera.cpp, ImagePlane.h, ImagePlane.cpp, etc.
You are free to use the header file Vector.h provided on the course webpage if
you wish. The file Vector.h has a sufficient implementation of a linear algebra
3D vector class, and a struct called Color. Note that the specification of classes
and methods here makes use of const and object references. Make sure you stick
to using those. Though you may not have used them in the past very much, it
is a very good habit to use them.
For the sphere and plane classes, the method float intersection(const
Ray& r) const computes the closest point of intersection of the object with
the ray. If there is no intersection, a negative value is returned. If there is an
intersection, the return value is the distance from the start of the ray to the
point of intersection.
The Scene object is a container that can hold planes and spheres in some
way that lets the Trace function get to each object to determine whether the
ray intersects that object, and if so, what color the object is. There are many
options for setting up such a container, all valid. You will have to select one.
You are free to create additional C++ classes, methods, etc. that have not
been explicitly called for here. In fact, you will probably need to. Using std
containters (e.g. vector, map, queue, etc.) is recommended whereever you see
the opportunity.
You will have to create a C++ implementation file called raytrace.cpp that
houses the main() function. You must also create a Makefile to compile and
link all of the code into an executable called raytrace.
When executed, raytrace will perform the ray trace render of the required
scene and write the data into an ascii ppm file. An example ppm file is provided
for you to examine. It can be viewed in any text editor to see its format, and
in any image viewer to see how its format translates into an image.
Description for 4050 Students
Using the ray tracer described above, the scene you must render consists of one
infinite plane and one sphere as follows:
• The plane has the point (0, 2, 0),the normal vector (0, 1, 0), and the color
(0, 0.5, 1).
• The sphere has the center (1, 2, 15), radius 3, and the color (0.5, 1, 0).
• The Camera has the position (0, 0, 0), view direction (0, 0, 1), up direction
(0, 1, 0), horizontal field of view 90 degrees (note that trigonometry
functions take radians as input), and aspect ratio 1.3333
• The image plane has 1024 pixels horizontally (Nx) and 768 pixels vertically
(Ny).
3
Description for 6050 Students
You will implement the ray tracing code as described above, with the addition
of a point light and lambertian shading at the intersections. One way to do this
is to modify the 3D objects to give them access to the light(s) and the shading
algorithm, so that the get color signature and algorithm can be modified to
perform the needed shading calculation.
The point light will be implemented as its own header file and implementation
file. The minimum content of the PointLight class is:
Class Class Data Class Methods
PointLight
• position
• color
• const Vector& get position() const;
• const Color get color() const;
Using the ray tracer described above, the scene you must render consists of
five infinite planes and one sphere as follows:
• The plane0 has the point (0, 2, 0),the normal vector (0, −1, 0), and the
color (1, 1, 1).
• The plane1 has the point (0, −2, 0),the normal vector (0, 1, 0), and the
color (1, 1, 1).
• The plane2 has the point (−2, 0, 0),the normal vector (1, 0, 0), and the
color (1, 0, 0).
• The plane3 has the point (2, 0, 0),the normal vector (−1, 0, 0), and the
color (0, 1, 0).
• The plane4 has the point (0, 0, 10),the normal vector (0, 0, −1), and the
color (1, 1, 1).
• The sphere has the center (1.1, 1.25, 7), radius 1, and the color (0.5, 0.5, 1).
• The Camera has the position (0, 0, 0), view direction (0, 0, 1), up direction
(0, 1, 0), horizontal field of view 90 degrees (note that trigonometry
functions take radians as input), and aspect ratio 1.3333
• The image plane has 1024 pixels horizontally (Nx) and 768 pixels vertically
(Ny).
• The point light is at position (−1, −1, 7) and has color (2, 2, 2).
All of the planes and sphere have Lambertian reflectivity.
4
Upload to handin
Create a folder called <username>. Put all of the following files into that folder.
There should be no subfolders.
Makefile
Vector.h
Camera.h
ImagePlane.h
Ray.h
Trace.h
Sphere.h
Plane.h
Camera.cpp
ImagePlane.cpp
Ray.cpp
Trace.cpp
Sphere.cpp
Plane.cpp
raytrace.cpp
output.ppm
(any other files you need to include)
If you are in 6050, you will also need to include:
PointLight.h
PointLight.cpp
Zip compress the folder into a single zip file, named <username>.zip. Upload
this file to the handin system. The course webpage has more guideance
and caveats if you need them.
