Hi, I`ve got a problem with rotating a triangle. I want to rotated the triangle after a key has been pressed. In pseudocode: if rightkeypressed then rotate all points in the negative direction end if leftkeypressed the rotate all points in the positive direction end the thing is that I can`t remember how it works with sin and cosine and all that stuff...could somebody please help me out and send me an e-mail at this address bwhw@magentammt.com THANX

2d or 3d?

2D. Below you can see the triangle and I want to make the 3 points (*) to move to the new coordinates and then I will plot the lines in between. So the trick is how to use the sine/cosine funtions work. If a press the rightkey the points should change position and then then traingle point into a new direction, sort of a ship in Asteroids??? Afterwardsi will add velocity and graity and stuff....i hope ;-)


*
/ \
/ \
/ \
*-------*

SORRY triangle got screwed....but I think you know what i mean...

Here you go:

    void RotatePts( int numPts, int* ptsX, int* ptsY, int centerX, int centerY, float angle ){    int   i;    float x, y, s, c;        s = sin( angle );    c = cos( angle );    for( i = 0; i < numPts; i++ )    {        x = ptsX<i> - centerX;        y = ptsY[i] - centerY;        ptsX[i] = ( int )( ( x * c ) - ( y * s ) ) + centerX;        ptsY[i] = ( int )( ( x * s ) + ( y * c ) ) + centerY;    }}    

ptsX and ptsY are arrays of 2D points.
centerX and centerY is the center of rotation.

------------
Cheers
Meduzza


Edited by - Meduzza on September 19, 2000 11:46:36 AM

Thanx Meduzza. Makes it a bit clearer now. Btw I`m programming in a new tool called ''Magenta''. Maybe you like it, you can check it out on http://www.magentammt.com. Leave me a message at the forum, if you like.

Greetz
FreeQ

"I never let my school interfere with my education"

Thanx Meduzza. Makes it a bit clearer now. Btw I`m programming in a new tool called ''Magenta''. Maybe you like it, you can check it out on http://www.magentammt.com. Leave me a message at the forum, if you like.

Greetz
FreeQ

"I never let my school interfere with my education"

Thanx Meduzza. Makes it a bit clearer now. Btw I`m programming in a new tool called ''Magenta''. Maybe you like it, you can check it out on http://www.magentammt.com. Leave me a message at the forum, if you like.

Greetz
FreeQ

"I never let my school interfere with my education"