# Transformation matrix problem!

hi… i need help about transformation, i mean rotation object.
i want to rotate object without glRotatef, so i multiple the points and matrix
ex.
rotate x
1 0 0 | | x | | x
0 cos -sin |X | y |=| cos * y + (-sin)*z
0 sin cos | | z | | sin * y + cos * z

my line program
double RadTheta=theta*3.14159265358979323846/180.0;

``````double CosRadTheta=cos(RadTheta);
double SinRadTheta=sin(RadTheta);

for (unsigned int i=1;i&lt;=o-&gt;nPoints;i++){
o-&gt;points[i].x=o-&gt;points[i].x;
o-&gt;points[i].y=(o-&gt;points[i].y*CosRadTheta)+((-SinRadTheta)*o-&gt;points[i].z);
o-&gt;points[i].z=(SinRadTheta*o-&gt;points[i].y)+(o-&gt;points[i].z*CosRadTheta);

}
``````

the problem is, the result is not corect. my object not rotate corectly. please help me… what i must do?
i have change degree to radian (angle*3,14…/180).

You fall prey for a very basic algorithmic mistake mathematicians usually make: you change the y coordinate but then use it again to compute the z coordinate, where you should have used the old value. You should use a temporary variable that will store the old y value, like

``````
old_y = y
// compute new y
// compute new z, with old_y

``````

oh… i see…
my point y is change!
wow thank you!