Cynthia Vaskis

SLM521 Spring 2004

Dropin #2 Assignment

4/2/04

File: drp2Hint.htm

Lesson Title: Math Calculations to Rotate an Object in 3D Space - Hint – Rotational exercises answers

a) The final triangle Point vectors are Point 1 = (x1, y1, z1) = (1, 1, 1), Point 2 = (x2, y2, z2) = (2, 2, 2), and Point 3 = (x3, y3, z3) = (1, 1, 2).

b) The final resulting triangle Point vectors after rotating the triangle +/-180 degrees about the X axis and then rotating the resulting Point vectors +90 degrees about the +Y axis and then the resulting Point vectors -90 degrees about the +Z axis leaves the final position back where it started with the original Point data. If you did not arrive at this solution then you performed some of the matrix operations incorrectly. In this case, if all the rotational matrices were multiplied together the result should be the Identity matrix. The Identity matrix has all ones down its diagonal (top left to bottom right corner) and zeros everywhere else in the matrix. The Identity matrix does no rotations or transformation of any vector since it is like multiplying a number by one.