CSC151.01 2015S, Class 12: A Design Perspective =============================================== _Overview_ * Preliminaries. * Admin. * Upcoming Work. * Extra Credit. * Questions. * Talk about quiz. * Optimism * A bit about design. * A bit about color theory. * Exploring some images and design spaces. Preliminaries ------------- ### Admin * New partners! * Mentor session Monday (tonight) at 7:00 p.m. * Work returned (I hope): Quiz 3. * Virtual machine somewhat available. URL to be announced. Get info on using it at ### Upcoming Work * [Exam 1](../assignments/exam.01.html). * Exam due in electronic form due Tuesday at 10:30 p.m. (free extension until Wednesday at 10:30 p.m.). * Exam due in printed form Wednesday (free extension until Thursday at review time). * Required epilogue due Wednesday at 10:30 p.m. (free extension until Wednesday at 11:00 p.m.) * No lab writeup for today! * Today will be more of a discussion day. That means we have time for questions on the exam and more at the beginning. * Reading for Tuesday * [Raster Graphics: Images from Pixels and Colors](../readings/raster-reading.html) * [RGB Colors](../readings/rgb-reading.html) ### Extra Credit Opportunities #### Academic * Education Film, Wednesday night * TEDx Grinnell, February 21 #### Miscellaneous * Read and comment on the new _Grinnell College Guide to Preventing, Reporting, and Responding to Sexual Harassment and Sexual Misconduct_. Angela Voos says that she would really like to know what kinds of things might go in an FAQ or instructional video about the reporting process. #### Peer Support (Afternoon Section) * Swimming, Conference Championships, February 13-15, The Osgood ### Recommended, But no EC * 2 <3 GC day on Wednesday. ### Questions _What's the difference between a drawing and an image?_ > A drawing is a conceptual thing; it's a collection of colored ellipses and rectangles. An image, in contrast, is a reference to GIMP's rendering of something visual. _How many tests is enough?_ > Make sure that you cover all the cases, but each test can cover multiple cases. I would guess that ten *different* tests would suffice. _Getting the rectangles on top of the image is challenging. Any hints?_ > See the exam for hints. _What's the relationship between `hshift-drawing` and `drawing-hshift`. > It's just the order of parameters. `(hshift-drawing AMT DRAWING)` vs. `(drawing-hshift DRAWING AMT)`. It's a matter of taste which you use. _Should we show you our experiments?_ > Yes. > Copy from the interactions pane. Paste into the definition pane. Select. Then comment out with semicolons (under the Racket menu). _Is there a procedure for finding the center of a shape?_ > Yes. > > _Can we give you multiple versions of a procedure in the hope that you will find one more to your liking?_ > If you indicate that the less correct ones are incorrect, yes. About Quiz 3 ------------ Problem 1: Find the difference between a number and the square of its square root (define error-root-squared (lambda (number) (- number (square (sqrt number))))) (define error-root-squared (lambda (x) (- x (* (sqrt x) (sqrt x))))) (define error-root-squared (lambda (val) (- val (expt (sqrt val) 2)))) * Remember: The thing you are subtracting from comes on the left. * We use `display` rarely. Problem 2: Given lots of weird code, figure out what it does. (define circ (hshift-drawing 0.5 (vshift-drawing 0.5 drawing-unit-circle))) * Is this defining a procedure or a value or ...? It's defining a value; a drawing. We would need a lambda for it to be a procedure. * When you are describing a drawing to someone else, you normally specify a variety of characteristics * Position: Left, top, bottom, right * Color * Type: Rectangle, Ellipse, Group * Height and width (given by scaling) * Center x and center y * Given all of that, how would you describe circ? * A circle * Height and width of 1 * Center at (0.5,0.5) * Top at 0, Left at 0, Bottom at 1, Right at 1 (define shape (lambda (h v) (hshift-drawing h (vshift-drawing v (hscale-drawing h (vscale-drawing v circ)))))) * Is shape a value or a procedure? It's a procedure - It has a lambda * Inputs (type): Two real numbers * Outputs (type): A drawing * Sample call: (shape 30 70) * First action: Vertically scale circ by 70. Result is an ellipse, centered at (0.5,35), top is 0, left is 0. Height is 70, width is 1. * Second action. Horizontally scale by 30. Result is an ellipse, centered at (15,35), top is 0, left is 0, height is 70, width is 30. * Third action. Vertically shift by 70. Change top, bottom, center-y. Result is an ellipse, centered at (15,105), top is 70, left is 0, height is 70, bottom is 140 * Fourth action. Horizontally shift by 30. Results is an ellipse, centered at (45,105), top is 70, left is 30, height is 70, width is 30. (define munge! (lambda (image) (drawing-render! (shape (* 1/3 (image-width image)) (* 1/3 (image-height image))) image))) * Procedure * Inputs (type): image * Outputs (type): image * Sample input: 600 x 450 drawing. * Compute 1/3 of width - 200 * Compute 1/3 of height - 150 * Call `(shape 200 150)` A bit about design ------------------ A bit about color theory ------------------------ Exploring some images and design spaces ---------------------------------------