c++ - Which one is more memory-consuming? Matrix or trigonometry transformations -


i have written 2 different ways transform euler angles normalized unit direction vector. i'm not sure 1 faster. 1 uses trigonometry operations or 1 transforms forward vector through matrix?

d3dxvector3 eulertodir(d3dxvector3 eulerrotation) { return d3dxvector3(sin(eulerrotation.x)*cos(eulerrotation.y), -sin(eulerrotation.y), cos(eulerrotation.x)*cos(eulerrotation.y)); }//convert euler angles unit direction vector. d3dxvector3 eulertodirm(d3dxvector3 eulerrotation)//same thing using matrix transformation. more accurate.  {                         d3dxmatrix rotmat;     d3dxmatrixrotationyawpitchroll(&rotmat, eulerrotation.x, eulerrotation.y, eulerrotation.z);      d3dxvector3 resultvec(0, 0, 1);//facing towards z.      d3dxvec3transformnormal(&resultvec, &resultvec, &rotmat);      return resultvec; }

thanks.

well, care about? memory usage stated in top level question? or speed, specified in description?

if it's speed, real way tell measure on target architecture/environment. trying guess waste of time.

the easiest way test performance of self-containted code snippets setup unit test this:

// setup first time starttime = getcurrenttimeinmicros() (int = 0; < num_iterations; ++i) {     // code performance tested } time endtime = getcurrenttimeinmicros()

then can endtime - starttime , see code took longer run.

if need test memory usage, print out sizeof() classes/structs if simple, else allocate them while instrumenting code valgrind/massif.


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