Create and modify rectangular shapes
#include <drawtk.h>
dtk_hshape dtk_create_rectangle_2p(dtk_hshape shp,
float p1_x, float p1_y, float p2_x, float p2_y,
int filled, const float *color);
dtk_hshape dtk_create_rectangle_hw(dtk_hshape shp,
float cx, float cy, float h, float w,
int filled, const float *color);
dtk_create_rectangle_2p() creates a rectangle whose the opposing corners are located at (p1_x,p1_y) and (p2_x,p2_y).
dtk_create_rectangle_hw() creates a rectangle with height h and width w and with its center located at (cx,cy) in the original frame.
shp, filled and color have the same usage and meaning as for other shape creation function:
shp can be used to modify a previously created shape. If it is non-null, the handle will be used to modify the shape referenced by shp: no new shape is created and the returned value is ensured to be shp in case of success, NULL otherwise. If shp is NULL, the function will attempt to create a new shape.
filled is set to 0 if the described shape should be a continuous line or a non-null value if the shape is supposed to be filled polygon.
color should point to a 4 float array containing a normalized RGBA value (i.e. each component is between 0.0 and 1.0).
In case of success these functions return the handle to the newly created or modified shape. If the shp argument is non-null, the handle returned is the same value. In case of error, NULL is returned.