c++ - Algorithm to draw a sphere using quadrilaterals -

i attempting draw sphere scratch using opengl. function must defined void drawsphere(float radius, int nsegments, int nslices), must centred @ (0, 0, 0) origin , must created using gl_quads.

firstly, "slices" sort of tapered cylinder shapes stacked on top of each other create sphere, , "segments" quads generated in circle generate wall/side of each of these tapered cylinder slices?

secondly, cannot seem find algorithms or examples of how make calculations generate sphere using quadrilaterals - example seem generated triangles instead.

edit

here have tried, in right direction, coordinate calculations off somewhere:

void drawsphere(float radius, int nsegments, int nslices) {   /*    * todo    * draw sphere centered @ origin using gl_quads    * compute , set normal vectors each vertex ensure proper shading    * set texture coordinates    */    (float slice = 0.0; slice < nslices; slice += 1.0) {         float lat0 = m_pi * (((slice - 1) / nslices) - 0.5);         float z0 = sin(lat0);         float zr0 = cos(lat0);          float lat1 = m_pi * ((slice / nslices) - 0.5);         float z1 = sin(lat1);         float zr1 = cos(lat1);          glbegin(gl_quads);          (float segment = 0.0; segment < nsegments; segment += 1.0) {             float long0 = 2 * m_pi * ((segment -1 ) / nsegments);             float x0 = cos(long0);             float y0 = sin(long0);              float long1 = 2 * m_pi * (segment / nsegments);             float x1 = cos(long1);             float y1 = sin(long1);              glvertex3f(x0 * zr0, y0 * zr0, z0);             glvertex3f(x1 * zr1, y1 * zr1, z0);             glvertex3f(x0 * zr0, y0 * zr0, z1);             glvertex3f(x1 * zr1, y1 * zr1, z1);         }          glend();     } } 

i'm not seeing radius being used. simple omission. let's assume rest of computation radius 1. should generate 4 values using 0-1 on both (x, y), , (z, zr), not mix within tuples.

so x1 * zr1, y1 * zr1, z0 not right because you're mixing zr1 , z0. can see norm of vector not 1 anymore. 4 values should be

x0 * zr0, y0 * zr0, z0 x1 * zr0, y1 * zr0, z0 x0 * zr1, y0 * zr1, z1 x1 * zr1, y1 * zr1, z1 

i'm not sure order since don't use quads triangles.