c++ - OpenGL: dynamically change loaded vertices -


used: qt 5.8 , qopenglxxx classes. opengl: core 3.3.

i'm drawing sphere , projecting plots of functions on (riemmann sphere). user may change radius dynamically slider, i'm unsure vertices of evaluated , projected function in case. see 2 options:

  1. use mapping of vbo data , modify data. or use glbuffersubdata.
  2. remove vbo , create again updated plot info.

there @ least 400 vertices, might more, question of performance crucial (well, it's crucial everywhere, though). think?

i've implemented first option qopenglbuffer::map() , worked great. given options, it's 1 not allocate/deallocate memory merely maps on cpu memory, so, think, case it's perfect. code sort of this:

void sphereradiuschanged(float new_radius) {    m_vbo.bind();     vertexclass* vbo_data = static_cast<vertexclass*>( m_vbo.map(qopenglbuffer::writeonly) );     if(vbo_data == nullptr)    {       ...    }     // here make necessary transformations.    ...     m_vbo.unmap();     m_vbo.release(); }

probably before you'll have make qopenglwidget's context current. function executed inside class's method, didn't it.


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