CS 457/557 -- Winter Quarter 2023

Project #5

Image Manipulation in a "Magic Lens"

100 Points

Due: February 21

This page was last updated: February 20, 2023

NEW! An Extra Credit opportunity has been added.

Requirements:

1. In computer graphics (and especially in visualization), there is a technique called a Magic Lens. A Magic Lens is some shape, usually a rectangle or circle, in which a different version of the display is drawn. Your job is to create a Magic Lens for an image display. Inside the Magic Lens, the image needs to be able to be magnified, rotated, and sharpened.

2. Be able to toggle between the Magic Lens being a rectangle and being a circle.

3. Draw a quadrilateral and map an image to it using a 2D Texture.

4. If you are using glman, your glib file could look something like this:

   ##OpenGL GLIB
   Ortho -5. 5.   -5. 5.
   LookAt 0 0 2  0 0 0  0 1 0
   
   Texture2D 5 image.bmp
   
   Vertex   magic.vert
   Fragment magic.frag
   Program  Magic						\
   	uSc	 <0. .5 1.>				\
   	uTc	 <0. .5 1.>				\
   	uDs      <0.01 ?? ??>				\
   	uDt      <0.01 ?? ??>				\
   	uRad     <0.01 ?? ??>				\
   	uMagFactor <.1 ?? ??>				\
   	uRotAngle <-3.14159 0. 3.14159>			\
   	uSharpFactor <0. 1. 5.>				\
   	uImageUnit  5
   
   QuadXY .2 5.
   

5. (uSc,uTc) are the (s,t) coordinates of the center of the Magic Lens rectangle or circle.

6. (uDs,uDt) are the width and height of the Magic Lens rectangle.

7. uRad is the radius of the Magic Lens circle.

Hints

• Inside the fragment shader, you need to see if the current fragment is inside the Magic Lens rectangle or circle. If it is not, do a texture lookup as normal.

• If it is, you need to be sure that the scaling and rotation you do to this (s,t) is with respect to the center (uSc,uTc) of the Magic Lens.

• When you want to do something to an image, you do the inverse of that to the (s,t) coordinates.

• So, if you want to scale the image by uMagFactor, you do ????? to its (s,t) coordinates.

• And, if you want to rotate an image, you would do:

  s' = s*cos(theta) - t*sin(theta)
  t' = s*sin(theta) + t*cos(theta)
  

  So, you would need to do ????? with the image's (s,t).

• The sharpening can be done with the code in the Image Manipulation notes. The sharpening is not done with respect to the center of the Magic Lense.

• The order should be something like:
  1. Translate by - (the center of the ML)
  2. Magnify
  3. Rotate
  4. Translate by + (the center of the ML)
  5. Sharpen

Extra Credit +5 Points:

Along with the magnifying, rotation, and sharpening, add edge detection using the Sobel filter approach. Note: this needs to take place in absolute space, not relative-to-the-center-of-the-magic-lens space.

It is OK if the Sharpening and the Extra Credit Edge Detection are mutally exclusive. Just show each of them independently. However, the Edge Detection should work with the Magnification and the Rotation!

The Turn-In Process:

1. Your turnin will be done at http://teach.engr.oregonstate.edu and will consist of:
   
   1. All source files (.cpp, .glib, .vert, .frag). You can zip this all together if you want.
   2. A PDF report with a title, your name, your email address, nice screen shots from your program, and the link to the video demonstrating that your project does what the requirements ask for. Narrate your video so that you can tell us what it is doing.
   3. Be sure your video's protection is set to unlisted.
   4. Do not put your PDF into your zip file. Leave it out separately so my collect-all-the-PDFs script can find it.

2. Use an image of your own as your report example. (Note: if you use glman or the bmptotexture.cpp code, the image needs to be a 24-bit uncompressed BMP.)

Be sure that your PDF file is turned-in separately (not part of a .zip file).

Rectangle	Circle

Grading:

Feature	Points
Something different happens in a rectangle	10
The rectangle can be sized and moved	15
The circle can be sized and moved	15
Magnification works	20
Rotation works	20
Sharpening works	20
Extra Credit: edge detection	5
Potential Total	105