== MatrixMath

This app is an example of how to produce a 3D effect using simple math.

== How does it work?

In the core of this example is the following function:

• (void) transform:(NSArray *)pts yrt:(CGFloat)yrt zrt:(CGFloat)zrt { if (pts==nil) return;

  CGFloat c1, s1, c2, s2;

  c1 = (CGFloat) cos(zrt); s1 = (CGFloat) sin(zrt); c2 = (CGFloat) cos(yrt); s2 = (CGFloat) sin(yrt);

  for (Point3D p in pts) { float x = p.x c1 c2 - p.y s2 - p.z c2 s1; float y = p.x c1 s2 + p.y c2 - p.z s1 s2; float z = p.x s1 + 0 + p.z * c1;

  p.x = x; 
  p.y = y; 
  p.z = z; 

  } }

It accepts a list of 3D points, Y rotation delta and Z rotation delta. It then transforms all of the points based on the rotation deltas. To display the points, use the x and z coordinates.

== How to test this example?

Download the code and run it. Drag your finger on the screen and see what you get.