Screen buffer manipulation
#include <drawtk.h>
void dtk_update_screen(dtk_hwnd wnd);
void dtk_clear_screen(dtk_hwnd wnd);
void dtk_bgcolor(float *bgcolor);
dtk_bgcolor() set bgcolor as the background color of the current rendering context. bgcolor should point to an array of 4 float corresponding to an normalized RGBA value. If unspecified, the background color is black.
dtk_clear_screen() fills the frame buffer with the background color of the window wnd.
dtk_update_screen() swaps the front and back frame buffers of the window wnd. Rendering is performed through double buffering, i.e. the draws are rendered on the back buffer which will be displayed on screen when a call to dtk_update_screen() will be performed. After an update, the content of the back buffer is undefined. So if the rendered scene does not rewrite the whole frame buffer, it is safer to call dtk_clear_screen() after an update of the screen.
These functions return no value.