Transforming coordinates

[LandR]

Hi,

I have a bit of a maths problem. I am drawing some triangles to screen with my program but my program draws to a paintbox (.net).

The left most coordinate of the paintbox is 0, the rightmost is 500. It's 500 pixels wide by 500 pixels high.

On this box I have drawn axis and a grid labelled from -1000 > 0 > 1000 for both X and Y axis.

The coordinates of the any vertex on the triangles range from (-1000,-1000) to (1000,1000).

I obviously can't draw them straight to the screen with these coordinates but my maths is so rusty. How can I transform the triangles co-ordinates so that:

-1000 = 0;
0 = 250
1000 = 500

??

I can write code to transform the coordinates I'm just not sure how I should go about it.

The initial problem was to find out of 1000 triangles how many contained the origin with their area. This I solved, it was simple enough. I decided though I would learn some graphics programming and allow you to draw the triangles to screen along with showing the calculations.

Sorry for being thick and Thank You if you help!

 

[Denver]

Would this work?

x/4+250

 

[Dr.Sid]

I usually do it like this: convert interval to 0..1 .. then it's simple.

So to get -1000 .. 1000 to 0..1 you do: (x+1000)/2000
To get the result to 0..500 you simply do ((x+1000)/2000)*500

 

[Earthborn]

Visual Basic had the SCALE (or WINDOW in QBasic) command, to define your own coordinate system. Isn't there something similar in whatever you are using?

 

[LandR]

Thank you