Question

In OpenGL, how do I read the current x/y translation in the modelview matrix? I know that you have to load the current matrix into an array and read the floats from there, but I don’t know precisely how to do it.

Answer 1

In order to retrieve the current modelview matrix you have to call the glGetFloatv function with GL_MODELVIEW_MATRIX parameter.

GLfloat matrix[16];  glGetFloatv (GL_MODELVIEW_MATRIX, matrix);  

From the documentation:

GL_MODELVIEW_MATRIX

params returns sixteen values: the modelview matrix on the top of the modelview matrix stack. Initially this matrix is the identity matrix.