Rastercaster Assignment

In this first project, you will create a sandbox for experimenting with fragment shaders and the OpenGL Shading Language (GLSL). You will render a single, screen-filling quadrilateral and paint designs on it using only algorithms that can be expressed in the fragment shader. This project is inspired by Shadertoy.

Each assignment in this course has two stages of requirements: later-week submission and full credit. To receive credit for the assignment you must meet all requirements. However, time is somewhat flexible. If you meet the later-week submission requirements by the due date, then you may take as much time as you need to meet the full credit requirements.

However, to prevent work from piling up at the end of the semester, only one assignment can be turned in per week. If another assignment has a due date in a given week, then you cannot turn in an earlier assignment.

Partial credit is not given. Assignments must meet all requirements. This system is meant to accommodate life's disruptions without sacrificing your learning and achievement.

Later-week Submission Requirements

You must complete these requirements by the assignment's due date:

• Create your project in a folder named rastercaster in the single Git repository that you are using for all your projects.
• Render a square that fills the viewport.
• Write a fragment shader that computes each fragment's color according to a function f with this interface:

  vec3 f() {
    // TODO: define a vec3 named color.
    return color;
  }

  The comment will be replaced by one or more statements that define the color. Call this function from main and use its return value to set the fragmentColor variable.
• Share in the #rastercaster channel a screenshot of your square. This requirement is waived if you will meet the full credit requirements by the due date.
• Commit and push your code to your Git repository no matter what state it is in.

If you meet these requirements, you are eligible for later-week submission.

Full Credit Requirements

You must complete these requirements in addition to the later-week submission requirements to receive credit for the assignment:

• Vary the color according to the fragment's coordinates, which are provided by the builtin gl_FragCoords.
• Display a textarea in the HTML in which the user can type in the body of function f. Expect the user to only enter the code that replaces the comment in the snippet above. They will not enter the function signature or return statement.
• On each change to the textarea, inject the user's code into your fragment shader, recompile, and re-render.
• Allow the user to reference a vec2 uniform named dimensions that holds the viewport's width and height in pixels.
• Allow the user to reference a vec2 uniform named mouse that holds the mouse's position in pixels.
• Allow the user to reference a float uniform named time that holds the number of seconds that have elapsed since the page was loaded.
• Design five algorithmic pieces of art using different definitions of f. Use any builtin GLSL functions or your own helper functions. Art is a subjective term. In general, each piece should be interesting in some aesthetic or algorithmic way and feel like it was crafted by a human artist.
• At least one design must reference mouse and be interactive.
• At least one design must reference time and animate.
• At least one design must use the discard instruction.
• Share in the #rastercaster channel screenshots of your five designs and their accompanying definitions of f in a text format that others can copy and paste. Each design must be unique amongst both your own designs and others' designs. _ Ensure that you can paste others' designs into your renderer to reproduce their results.
• Your code must be cleanly formatted, the variable names must be meaningful, and comments should explain non-obvious code.
• Your Git log should reveal a steady pattern of commits. In general, you should commit and push after every work session.

When you are ready to claim your credit, send your instructor a direct message. Ensure that all requirements have been met. If they have not, you will not receive credit and will have to submit again some other week.