Shooting and Moving

• Goal for the day
• There is one big idea here.
  • If I am located at (x,y), traveling at an angle of θ and I take a step.
    • x will change by stepSize*cos(θ)
    • y will change by stepSize*sin(θ)
  • 
    • r is the size of the step.
• Note what is really important here is that each object keeps track of it's own transformation information.
  • The object must maintain
    • current rotation 0 ≤ θ < 360
    • current location (x,y)
  • This gets updated when the object is moved.
  • And is used when the object is drawn.
    • Center the object at the origin.
    • Rotate by θ
    • Scale if needed.
    • Translate by (x,y)
• I added shots because I wanted to.
  • How could we modify this to check for impacts avoid collisions?
  • Remeber, we can querry the contex for the current transformation matrix.
  • So we could compute our "center" in canvas coordinates.
  • And projecting a point from the center, we could also compute our "scaled" radius.
  • So we could build a vector of scene elements.
  • And compute collision as before.