c++ - Rotation in OpenGL ES 2.0 -


i have 2x4 matrix. represent 4 points of square. need rotate said square x radians (which can converted degrees) rotation point/ anchor being center of square.

since opengl es 2.0 has removed transformation functions (glpush/glpop, glrotate, gltranslate, glscale, etc.) need rotation myself. can me write function preform rotation?

rotations in 2d can expressed (where theta in radians):

cs = cos(theta); sn = sin(theta);  out.x = in.x * cs - in.y * sn; out.y = in.x * sn + in.y * cs;

the above linear equations can expressed 2x2 matrix (in american way, arranged in columns):

|  cs  sn | | -sn  cs |

the matrix can expanded add translations:

|  cs  sn  tx | | -sn  cs  ty | |   0   0  1  |

in openggles 2.0 packing 4 points array of 2 components, need transform them in vertex shader. compute above matrix , send down pipeline using uniform.

this can quite long if don't know opengl es 2.0 pipeline. require more info?


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