CG Lecture 5, Thurs 2016-09-08

W Randolph Franklin, RPI

  1. Notes from yesterday:

    1. gasket4 shows how to do 3D with a depth buffer.

      Each pixel now stores

      1. RGB color of the object that was drawn at that pixel
      2. distance (depth) to that object.

      When a new object is drawn over that pixel, it replaces old color and depth only if the new object is closer. So, close objects hide distance objects.

      We'll ignore the problem of an object that covers only part of the pixel.

    2. gasket5 shows an interactive program with a slider and callback. The user changing the slider causes a javascript function to be called.

  2. iclicker questions.

  3. Homework submissions: Instead of putting your files on afs, it's ok to submit a zipped file, containing your .js and .html files and the utility files needed to run it. It must be organized so that if we unzip into a random location and point the browser at the .html file, then it will work.

  4. Graphics display hardware: The progress of Computer Graphics is largely the progress of hardware. We'll see more of this later. However, here's an intro.

    1. What physical principles are each type of HW based on?

      1. CRT: certain rare earth materials emit photons when hit by electrons. Explaining this is what got Einstein his Nobel (not relativity).
      2. LCD: electric field causes big asymmetric molecules to untwist so that they no longer rotate polarized light passing through them.

    2. What engineering challenges required solving?

      1. Shadow-mask CRT: electron beams travel varying distances at different angles, but don't hit the wrong phosphor even as the system gets hotter. The precision is 0.1%.
      2. Hi-performance graphics requires hi bandwidth memory.
      3. Virtual reality headsets require knowing where your head is and its angle (harder).

      Think of 3 ways to do this.

    3. What tech advances enabled the solutions?

      1. Raster graphics requires cheap memory.
      2. LCD panels require large arrays of transistors.

  5. Note on Engineering Grounded In Reality and famous graphics alumni.

  6. Executive summary of Portability And Standards.

  7. We'll continue with the textbook powerpoint slides.

    1. 3_1, Programming with WebGL Part 3: Shaders
    2. 3_2, Programming with WebGL Part 3: Shaders