JesterN

i need to rotate a cylinder in open GL, but the basic rotation is around the middle point, if i need to rotate around one edge is there any solution?

i can mask half of it, but it's gonna cover other objects

otherwise i can use linesegment in sketch but there's no 3d in it...

Hi there,
i need to rotate a cylinder in open GL, but the basic rotation is around the middle point, if i need to rotate around one edge is there any solution?
i can mask half of it, but it's gonna cover other objects
otherwise i can use linesegment in sketch but there's no 3d in it...
Any idea?
Alberto


rotating-cylinder-in-open-gl

you can do this using gl.sketch and proper ordering of calls to gltranslate/glrotate.

to rotate something offset from it's center point, you call glrotate before calling gltranslate with the offset amount:

Great robtherich, this is exactly what i needed. The sketch object seems to have a lot of possibilities, so now i see... i have another question i kept for quite some time, is it possible to group objects together in openGL in a way of using them as a macro-new-defined object? for example a Sphere and a Cylinder form a pendulum, if i link the sphere relative to the cylinder i can just rotate the cylinder thing without specifying the rotation for the sphere?

as long as you're not doing anything too intensive, you could tell a sketch (mysketch1) to drawobject mysphere and drawobject mycylinder (name your sphere and cylinder)

then you'd call "drawobject mysketch1" on a new SECOND sketch, "mysketch2"

rotating cylinder in open GL