How to construct a QTransform?

[lni]

Hi,

I have 3 known points, which are mapped to another 3 known points.
p1 -> p1'
p2 -> p2'
p3 -> p3'

From those 6 points, how can I construct a QTransform?

Thanks!

[wysota]

Are we talking 2D or 3D? And is the mapping linear or not?

[lni]

Are we talking 2D or 3D? And is the mapping linear or not?

It is for 2D linear mapping, but perhaps 3D may be needed later...

[wysota]

Then you need to solve the following equation:
ax + by + c = 0

Substituting x and y with coordinates of your three points to calculate a, b and c and then place them in the matrix. Of course x and y correspond to p1.x and p1'.x and not p1.x and p1.y. You need a similar equation for p1.y and p2.y

http://en.wikipedia.org/wiki/System_of_linear_equations
http://en.wikipedia.org/wiki/Gaussian_elimination