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author | unknown <paulx161@umn.edu> | 2021-02-02 18:35:09 -0600 |
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committer | unknown <paulx161@umn.edu> | 2021-02-02 18:35:09 -0600 |
commit | 7ea1b2c0320d74152d33e74718a39319a7a0e507 (patch) | |
tree | 7c2995f547889f00e381449b5c91dbb0abd1a0c3 /worksheets | |
parent | Added /dev/gfxtest/* (diff) | |
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Added worksheet and support code for assignment 2
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-rw-r--r-- | worksheets/a2_carsoccer.md | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/worksheets/a2_carsoccer.md b/worksheets/a2_carsoccer.md new file mode 100644 index 0000000..95170c4 --- /dev/null +++ b/worksheets/a2_carsoccer.md @@ -0,0 +1,156 @@ +# Assignment 2 (Car Soccer) Worksheet + +## Definitions + +Use the following C++ style pseudocode definitions for Q1 and Q2: + +``` +/* Use this Point3 class to store x,y,z values that define a mathematical + * point (i.e., a position) in 3-space. + */ +class Point3 { + float x; + float y; + float z; +}; + +/* Use this Vector3 class to store x,y,z values that define a vector in + * 3-space. Remember, mathematically, a vector is quite different than + * a point. It has a direction and a magnitude but no position! + * For vectors it is often useful to be able to compute the length, + * also known as the magnitude, of the vector. + */ +class Vector3 { + float x; + float y; + float z; + + // returns the length (i.e., magnitude) of the vector + float Length() { + return sqrt(x*x + y*y + z*z); + } +}; + + +/* In C++ and other languages we can define operators so we can use + * the +, -, =, *, / operations on custom classes. Like many graphics + * libraries, this is what MinGfx does to make it easy to work with + * points and vectors in code. For example, recall from class that + * if we have a point A (Coffman Union) and we add a vector (direction + * and magnitude) to this, we arrive at a new point B (e.g., Murphy Hall). + * Conceptually, a point + a vector = a new point. Mathematically, it + * does not make sense to add two points, but it does make sense to + * subtract two points. The "difference" between the Murphy and Coffman + * points is a vector that tells us the direction and magnitude we would + * need to walk from Coffman to get to Murphy. Here's how we can write + * that in code using Point3, Vector3, and operators like + and -. + * + * Point3 murphy = Point3(5, 8, 0); + * Point3 coffman = Point3(4, 6, 0); + * Vector3 toMurphy = murphy - coffman; + * + * // or, if we were given coffman and toMurphy we could find + * // the point "murphy" by starting at point "coffman" and adding + * // the vector "toMurphy". + * Point3 murphy2 = coffman + toMurhpy; + * + * The code that defines these opertors looks something like this: +*/ + +// a point + a vector = a new point +Point3 operator+(Point3 p, Vector3 v) { + return Point3(p.x + v.x, p.y + v.y, p.z + v.z); +} + +// a point - a point = a vector +// the dir and magnitude needed to go from point point B to point A +Vector3 operator-(Point3 A, Point3 B) { + return Vector3(A.x - B.x, A.y - B.y, A.z - B.z); +} + +// a vector * a scalar = a new vector with scaled magnitude +Vector3 operator*(Vector3 v, float s) { + return Vector3(v.x * s, v.y * s, v.z * s); +} + + + +/* Given all these tools, we can define additional classes for geometries + * that are useful in graphics. For example, we can represent a sphere + * using a Point3 for the position of the center point of the sphere and + * a float for the sphere's radius. + */ +class Sphere { + Point3 position; + float radius; +}; +``` + +## Q1: Eulerian Integration + +In computer graphics and animation, there are many forms of integration that +are used. For simple physics models like we have in Car Soccer, Eulerian +Integration is good enough. Eulerian Integration uses velocity and position +information from the current frame, and the elapsed time to produce a position +for the next frame. Write pseudocode for determining the position of the sphere in the +next frame: + +*Hint: think back to the motion equations from introductory physics. Or, look +around in the assignment handout.* + +``` +Vector3 velocity = Vector3(1.0, 1.0, 1.0); +float dt = 20; // milliseconds + +Sphere s = Sphere { + position: Point3(0.0, 0.0, 0.0), + radius: 5.0, +}; + +s.position = /* --- Fill in the next frame position computation here --- */ +``` + + + +## Q2: Sphere Intersection + +In this assignment, you will need to test intersections between spheres and +other objects. Using the information contained within each sphere class, +write pseudocode to determine whether or not two spheres are intersecting +(which you can use for car/ball intersections): + +``` +bool sphereIntersection(Sphere s1, Sphere s2) { + /* --- Fill in your sphere intersection code here --- */ + + +} +``` + +To check that your intersections work, try working through the math by hand for the +following two cases. You can write out the math on a scrap piece of paper. You do +not need to include that detail in this worksheet. But, do change the lines below where +it says "Fill in expected output" to indicate whether True or False would be returned: + +``` +Sphere s1 = Sphere { + position: Point3(0.0, 1.0, 0.0), + radius: 1.0, +}; + +Sphere s2 = Sphere { + position: Point3(3.0, 0.0, 0.0), + radius: 1.0, +}; + +Sphere s3 = Sphere { + position: Point3(1.0, 1.0, 0.0), + radius: 2.0, +}; + +print(sphereIntersection(s1, s2)); +/* --- Fill in expected output (True or False) --- */ + +print(sphereIntersection(s1, s3)); +/* --- Fill in expected output (True or False) --- */ +``` |