Original Post
I've been playing around with OpenGL recently and I've run into a problem that I seem unable to solve... I think I'm missing something basic about how OpenGL handles the matrix stack.
Basically what I'm trying to do right now is implement a virtual 'trackball' on my screen so that the user can manipulate the displayed model. I'm trying to do rotations, basically what happens is the user clicks inside the virtual trackball and then drags to a position inside the trackball tracing out a vector inside a virtual sphere. A rotation is applied around this vector the angle of which is the length of the vector in radians.
So here's the code that's messing up:
If I take out the glMultMatrixd is works as expected but the rotation isn't persistent, i.e on the next mouse click the model gets reset to the center of the screen regardless of the rotation I applied b4. I want the rotation to be persistent so that the user can click again and the model will rotate around this new vector. With the above code it gets really crazy like the rotations go waaay outside of the viewport. a very small rotation produces huge results.
I was trying to save the matrix with the GetDoublev and then load it on the next frame (above code is called every frame) but it's not working. Anyone have any suggestions?
Thanks in advance!!
Basically what I'm trying to do right now is implement a virtual 'trackball' on my screen so that the user can manipulate the displayed model. I'm trying to do rotations, basically what happens is the user clicks inside the virtual trackball and then drags to a position inside the trackball tracing out a vector inside a virtual sphere. A rotation is applied around this vector the angle of which is the length of the vector in radians.
So here's the code that's messing up:
if(matrix[1]) { glMultMatrixd(matrix);}glRotated(rot_vector.length()*57.2957795, rot_vector[0], rot_vector[1], rot_vector[2]);glGetDoublev(GL_MODELVIEW_MATRIX, matrix);If I take out the glMultMatrixd is works as expected but the rotation isn't persistent, i.e on the next mouse click the model gets reset to the center of the screen regardless of the rotation I applied b4. I want the rotation to be persistent so that the user can click again and the model will rotate around this new vector. With the above code it gets really crazy like the rotations go waaay outside of the viewport. a very small rotation produces huge results.
I was trying to save the matrix with the GetDoublev and then load it on the next frame (above code is called every frame) but it's not working. Anyone have any suggestions?
Thanks in advance!!
