Question

Does anyone know how to acquire intersection point(x,y,z) of line and an object in opengl es 2.0. I need basic algorithms or links. i was searching for this answer for 2 days and i couldn`t figure out how to do it.

Answer 1

For faster rendering on embedded devices avoid using all of the object’s vertices.

Ultimately you have to use tricks:

1) When detecting collision, develop as per your convenience methods to approximate object

2) Use single point to represent object, and check if

foreach(LINEPOINTS)
  if (MVP * LINEPOINTS).x or .y or .z equals (MVP * objectCentre).x or .y or .z

3) Use seperate way, (anyother language that you know like I use Perl) for finding centre,
as simple as

count = numofvertices
foreach vertices
    sumx += x;
    sumy += y;
    sumz += z;
centreofmass = {sumx/count, sumy/count, sumz/count}

use this value directly as private float[] final objectCentre = centreofmass

4) When this works, use more vertices (like edgecentres or corners of shapes), that too precalculated in someotherlanguage and then used in java app as mentioned before, because object will have huge number of vertices and approximating does not mean it does not look nice, it will look nice but spend more time to find ways that suit you app